# Building an Integrating Sphere ...



## precisionworks

There are already articles on CPF about different light measurement designs, but none that I found on Integrating Sphere construction. For me, finding a hollow, white sphere was the first challenge. After quite a few searches, a 12" hollow styrene sphere was found at Barnard (phone 888-584-3637). Price with shipping was about $38 - the shipping seemed high until the sphere arrived in a carton almost twice as big as the item. 








A top and bottom plate were cut from 1/2" plywood. The sphere measured exactly 12" diameter, and the plywood was cut to 11 7/8" (square) to give the sphere a small amount of compression when assembled.






Four posts (also 11 7/8") were cut to connect the upper & lower plates, and the posts and plates were assembled with yellow glue & brad nails.












The sphere was placed inside the assembly, and four side panels were cut from 1/8" plywood. These are attached with yellow glue & brad nails.






The upper hole is cut with a holesaw to match the diameter of the light meter sensor. The light port is also cut with a holesaw to fit the light tube. 






A piece of 2 3/4" stainless tube is used here, but PVC pipe would work just as well. The light tube was coated with Satellite City Special T Super Glue, the inside of the hole was misted with accelerator, and the tube was inserted & twisted until the glue set (about 5 seconds)







Except for applying a finish to the wood, the IS is complete. The light meter is an Extech EA31 (range to 20,000 Lux). It was found on Amazon for under $100 & gives repeatable readings. Since the IS is a comparative device, my concern is that the readings are the same every time a light is retested.

Here are the first Lux readings obtained:


Malkoff M60 in Surefire 6P host - 10,400 

Surefire E1B on high setting - 6,540

Surefire U2 on high setting - 6,350

Novatac 120P on high setting - 5,790

Muyshondt Nautilus high setting - 4,900

Surefire L4 - 3,840

Malkoff M60LL in Surefire G2 - 3,330

Surefire E2L (single stage Cree) - 2,970

McGizmo Sundrop - 2,550

Surefire E1L (single stage Cree) - 2,180

Muyshondt CR2 Ion - 1,580

Again, these are comparative readings ... they are not absolute.


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## Blue72

That is a cool set up.

What difference in readings do you get with and without the sphere


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## adamlau

Very interesting. Now to measure some light with big power  .


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## half-watt

very nice construction job. kudos to you for your fine effort and excellent fabrication.

based upon some of the comparative readings, not sure if the setup is truly integrating. obviously, the meter is still reading in Lux. that said, in some respects it still seems to be reading mainly "hotspot" (Lux) readings (plus some, perhaps???) and may not be truly integrating. why would i say this? well,...

unless i have my head screwed on totally backwards, just compare two or three of the SF lights. SF rates the E1B at, IIRC, 80lm, the U2 and L4 at 100lm. now, the lux (hotspot) readings of these three lights are quite different, i would imagine, based upon hotspot (E1B > U2 > L4). your readings are ordered in accordance with what i would imagine it would be if only HOTSPOT was considered (again, E1B > U2 > L4).

your readings indicate, comparatively, for those three SF lights what one might expect from Lux/hotspot readings and not what SF claims for Lumen ratings.

i would like to know what the Lux readings are at a straight line linear distance equivalent to the diameter of the sphere. how different are they from the Lux readings using the sphere? how do they compare to each other?

all this is *NOT* said to denigrate in any way either your exemplary initiative, nor your fine efforts. i just have these questions based upon the readings obtained and published in your Post.


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## precisionworks

> it still seems to be reading mainly "hotspot"


I understand your thoughts, and agree that some of the readings are not what I expected. Perhaps 12" is too small for full integration of the reflected light. However, the diffusion dome of the meter is looking straight down at the bottom of the sphere, where it sees no direct light. The hotspot from the light is projected against the sphere wall opposite the light port.

I may need to fabricate & install a baffle at the bottom of the sensor dome port. This would lower all readings by an equal amount & eliminate any overreading from a hotspot.

FWIW, Chevrofreak used essentially the same locations for both light port & sensor port:


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## McGizmo

Very cool!! :thumbsup: You might want to install a PTFE or other white type baffle blocking the meter from direct viewing of your source port. I believe most IS have such a baffle.
*EDIT: Nevermind!  

BTW, I have a 6" sphere with 1.250" port access and it seems to do fine with anything I can introduce properly to the sphere. *


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## half-watt

understood about the relative positions of the light source and sensor. just having the right angle relationship between source and sensor does NOT guarantee that proper integration is occurring. one could use one flat mirror to reflect light at a right angle from source to sensor. this obviously would not be integration, and the meter would only read the hotspot/highest/brightest portion of the reflected light. i'd like to try to determine how much (in a purely gross qualitative sense; not a quantitative sense) integration is really taking place in your sphere.

it still seems to be reading the reflected hotspot plus possibly some non-hotspot reflected light, and NOT integrating more/"all" of the light output. if it did the U2 and L4 ought to read higher than the E1B (again, unless i have my head screwed on backwards).

if you measure the Lux output straight on at 12" (the diameter of your sphere) without the sphere, there are only three relative possibilites. the readings of each will be higher, lower, or the same when compared to the "in sphere" readings.

if higher, then your sphere [readings] and Lux meter are only measuring SOME of the reflected light which appears to the meter to be reduced by the reflection in the sphere.

if lower [, but still the same relative relationship E1B > U2 > L4], then there is some integrating taking place, but probably (again, based upon U2 and L4 being SF rated at 100lm vs. E1B rated at 80lm) still to a degree only measuring the brightest portions of the beam output. 

if lower, but a different relationship (e.g. E1B, NOT being the highest reader), then there may be something amiss in the straight line Lux readings as one would expect the E1B to be the brightest (i really don't know how they compare in Lux testing; i'm just guessing here based upon the brightspot of each light - i own all three of these SF lights).

if the same (i don't expect this to be the case), then no integration is taking place.

this is the values of performing a "sanity" check by taking normal straight line/linear Lux readings. i suggest using the very close 12" distance since that is the diameter of your sphere, or use 24" (or any other distance - easier to use a multiple of the sphere's diameter - makes purely mental calculation of the inverse square easier; i can't easily do inverse square with decimals in my head) and use the inverse square law of radiating energy to compare the results to the sphere's Lux reading.

again, excellent work on the concept and fabrication. obviously, a valuable original Thread and Post on your part.


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## Norm

I'll start by saying I know nothing about this subject but I would have thought the best position for the light sensor would be close to the input port, if the tube at the input was set an inch or two into the sphere it would also act as a baffle.
Norm


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## MrGman

Very interesting work indeed, Can you see white light coming through the sphere to the outside world? Is it glowing? If so you are losing light because the material is not as reflective as it should be. What ever amount of light is coming out is not being internally reflected. 

Half-watt's test sounds valid as a way to determine if its integrating or just getting most of the hot spot readings.

Also what does IIRC mean?


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## half-watt

IIRC = if i recall correctly


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## precisionworks

I looked again in the sensor port (which is 1/2" plywood followed by 1" of styrene foam) and saw that the styrene foam is capturing a some of the spillbeam, leading to an inflated reading on some lights.

Since the sensor port is 2" diameter x 1 1/2" thickness (to the inside of the sphere), a piece of 2" tubing was painted flat black inside, and pushed into the port. The new readings are as follows:

Malkoff M60 in Surefire 6P host - 2,880 

Surefire E1B on high setting - 1,780

Surefire U2 on high setting - 1,774

Novatac 120P on high setting - 1,582

Muyshondt Nautilus high setting - 1,370

Surefire L4 - 1,203

Malkoff M60LL in Surefire G2 - 935

Surefire E2L (single stage Cree) - 864

McGizmo Sundrop - 727

Surefire E1L (single stage Cree) - 614

Muyshondt CR2 Ion - 454

If you look at these numbers as a percentage, they are nearly identical to the first test without the black tube baffle. The numbers below are in percent, with the Malkoff M60 used as a 100% standard (numbers are test 1/test 2)


Malkoff M60 in Surefire 6P host - 100/100 

Surefire E1B on high setting - 63/62

Surefire U2 on high setting - 61/61

Novatac 120P on high setting - 56/55

Muyshondt Nautilus high setting - 47/48

Surefire L4 - 37/42

Malkoff M60LL in Surefire G2 - 32/32

Surefire E2L (single stage Cree) - 29/30

McGizmo Sundrop - 25/25

Surefire E1L (single stage Cree) - 21/21

Muyshondt CR2 Ion - 15/16

To me, the only reading that falls outside the expected lumen curve is the E1B. I bought a few of these and sold all but this one (which is on a McGizmo Ti McClicky Pak host, not the standard SF body). It has about the same low setting as any other E1B, but the high is the brightest of any that I've seen. Maybe SF put the wrong driver board in this head, maybe the emitter bin is at the top of the XR-E series, but without a doubt it is brighter than the U2 on a ten foot, white wall bounce.

A five foot ceiling bounce gives the U2 @ 42, the E1B @ 44.


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## half-watt

regarding your E1B observations: understood. seen this type of thing before (though mine was a Fenix P1D-CE which was brighter than four P1D-Q5's; the fifth P1D-Q5 was brighter though). it's probably the LED and *NOT* the E1B electronics responsible for what you are seeing. the disparity b/t U2 and L4 readings though still indicates more of a Lux type of reading rather than a Lumen type of reading, if i'm not mistaken (and feel free anyone to correct me if you feel that i am mistaken). however, this assumes that SF has correctly rated both the U2 and L4. SF appears to rate conservatively and perhaps they are both >100lm, but that the U2 is more conservatively rated??? don't know. also, only one specimen of each light is being used, so perhaps the U2, in this case, has more overall light o.p. than the particular L4 specimen being tested???

also, thinkin' a bit more, i think my early contention that you would get a higher Lux reading in the sphere vs. linear is just plain wrong. since the sphere diffuses the light, including the hotspot. this ought to even out the brightness. looks like i did have my head screwed on backwards - wouldn't be the first time!!!


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## precisionworks

> I would have thought the best position for the light sensor would be close to the input port


The sensor can be located in a number of positions, so long as the sensor does not see either the light source or the hotspot. The easiest sensor position (for a closed sphere) is 90° to the source. Larger spheres are split in half and hinged - this allows the source to be located in the exact middle of the sphere, with a baffle blocking direct radiation to the sensor.



> Can you see white light coming through the sphere


The foam is 1" thick, so none of my lights (even the 240 l Malkoff) penetrates.


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## MrGman

I just checked with one of the optical engineers here at work. The integration sphere must have a baffle so it cannot read the light source directly. In case no one has already made that certain.


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## precisionworks

I understand your concern about the baffle, and the need for no direct light to strike the sensor dome, or strike inside the sensor port where it would reflect into the sensor dome. 

I did conduct a test for this. All room lights were turned off. The photosensor was removed from the top port and a flashlight was turned on & placed in the light port. I inspected the sensor port to make sure that no direct light was hitting the inside of the sensor port tube. In a dark room, the only light I saw was the light at the bottom of the sphere. For this reason, I believe that the meter is reading an integration of total luminous flux.

A calibration light source is something I'd like to find. The commercial ones plug into a wall outlet, and the output varies with the size of the sphere. That way, the relative readings could be converted, using a conversion factor, to lumens.


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## MrGman

I looked inside the IS we use at work today and also talked to our head PhD Optical Engineer about this. The Baffle is very important in not having false high readings. Its a small circular 2 dimensional object that is literally directly between the 2 ports. Its tilted up in the circular cavity so that any light directly from the input port would cast a circular shadow on the meter port. Since its on an curving slope the best way to describe is that it is parallel to the flat vertical opening surface for the meter port. It is the same flat white color/texture as the rest of the sphere. 

In this way lights with a wide angle head cannot have any direct light impingement in the meter port.

You may not think that the lights are going directly to the port but the results you posted may have a false high reading. There should be nothing that sticks into the inside surface from the outside world that goes beyond the wall thickness. 

You have gone this far, might as well try it, then divide all your readings by 36 (radius squared) to see how close they get to the rated lumens of the lights you use. This may be an over simplification, but its quick and easy for now. May need a fudge factor. The sensor in the one at work is only about 1.8" diameter opening. 

I notice on the one I keep testing with at work (its a 6 inch sphere by the way and its calibrated with the meter and our engineers trust the readings of it for all kinds of LED light sources), that if I move the light into the sphere at all the readings actually go down. It appears the best readings are with the light source directly at but not past the opening of the sphere. That is why I believe that the black tube at the inlet port is really going to affect the readings negatively. If you are going for all comparative readings, it still doesn't buy anything to have that black tube on the inlet. Real IS's have no such thing. 

I would expect all the readings to go down some what with the baffle installed. 

In theory a 235 lumen light source of white light should read 8460 lux if the baffle does its job right. 

If I am off on these numbers it means I should have gone to bed already. Good luck.


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## precisionworks

> it still doesn't buy anything to have that black tube on the inlet. Real IS's have no such thing.


Real IS's aren't made with hollow stryofoam balls & cost just a little more than $38 ... and the light/lamp/LED being tested is typically located centrally in the sphere, separated from the photo detector by a baffle that prevents direct light readings. I couldn't figure a way to easily construct such a sphere, which involves cutting the sphere in half to produce two hemispheres hinged together.

The baffle probably should be installed, as it is common to most IS designs available, including the simple design I used:






In the example above, there is a baffle both above & below the light port (entrance aperture). The dual baffle arrangement is most likely used to prevent a wide angle light source (like a McGizmo Mule or Sundrop) from directly striking either the photodector or the bottom of the sphere - both or either of which would give an inflated reading.



> the results you posted may have a false high reading


I also believe they did. The photo detector was looking through the 1" styrofoam sphere wall. That's a little more than 6 square inches of reflectance being added to the reflectance from the "bottom" of the sphere. The black tube does have a high negative impact, taking the first reading of 10400 down to 2880, a reduction on almost 73%. But, the percentage values from the first test are awfully close to those of the second test - the SF L4 having the largest test to test spread. Not a great surprise, with the wide angle, flood type beam dispersion of the L4.

I'll see if I can figure a way to mount both the lower & upper baffles.


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## MrGman

I just talked to my PhD Engineer coworker at lunch about the dual baffles. The only reason for multiple baffles is for units that have multiple input ports. Only one baffle is needed and used for a specific input location to the photodetector port. Our integration spheres only have 1 baffle. FWIW.


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## precisionworks

> divide all your readings by 36 (radius squared) to see how close they get to the rated lumens of the lights you use.



Even though the OD is 12", the ID is 10" (walls are 1" thick). My radius squared is 25 ... but the flat black tube to the light meter dome absorbs enough that my "corrected" radius squared becomes 12.5.

I've thought about this quite a bit, and plan to line the flat black tube with a bright white tube that has an angled cut end. As long as that angle is 45° or more, the long side of the tube will have the same effect as adding an internal baffle - direct light from the flashlight lens will strike the outside of the tube but not the inside where an inflated reading will result. At that point, the factor of 25 will probably be correct.


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## MrGman

I am confused??? Are you talking about the cut up maglight in the inlet port or is there something else on or around the actual light meter you use as your photodetector? I would have no built up walls to prevent light from coming in from all around the sphere to the detector except for the one baffle directly in line with the front end of a light at the inlet port. If you can't put it inside the sphere because the sphere is now sealed up, I would put it only at that limited angle along the opening of the inlet port that faces directly to the detector. 

I also realized that your inside diameter was smaller than your outside one about 1 minute after I made that last post but I figured you would figure that part out real quick since you built it and would just see what you came up with anyway as you did, so I didn't bother to send a correction.


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## precisionworks

I was able to remove the straight cut tube that points down from the sensor port (painted flat black inside) & replace it with a 45° angle cut tube painted flat white inside. The long point of the 45° cut faces the light port so that any spill will hit the point & be reflected. The opposite side of the tube is in the shadow of the 45° point, so no direct light can strike the inside of the tube. The reason for the flat white is to try to match the reflectance of the Styrofoam interior.







The output of the lights are still in the same order except that the U2 moves above the E1B. I played with the radius squared numbers and settled on 18 as being as close to published figures as possible. 18 = 4.24" radius, or about 8.5" internal sphere diameter. Best scientific guess is that the Styrofoam is not as bright as a commercial sphere, so my 10" is producing results like a commercial 8.5" sphere.

Latest (hopefully last) revision. Here are the readings. First reading is my lumen calculation, followed by factory stated lumens:

Mac's Custom P7 (AW C-cell LiIon) = *782 lumens *(about 800 per Mac)

Malkoff M60 with 60Ω Sandwiche Shoppe mod = *15/192 lumens* (235 per Malkoff website)

Surefire U2 = *7/114** lumens* (2/100 per SF)

Surefire E1B = *11/113 lumens* (5/80 per SF)

Novatac 120P = *.23/11/99 lumens* (.23/10/120 per NovaTac)

Muyshondt Aeon = *10/92* *lumens* (?/114 per Muyshondt site)

Muyshondt Nautilus = *6/91* *lumens* (?/107 per Brightguy site) 

McGizmo LunaSol 20 = *9/73 lumens *(9/78 per Don)

Surefire L4 = *66 lumens* (100 per SF)

M60LL in Surefire G2 = *61 lumens* (80 per Malkoff site)

Surefire E2L (single stage Cree) = *57 lumens* (45 per SF)

McGizmo SunDrop = *46 lumens *(40-50 per Don)

Surefire E1L (single stage Cree) = *40 lumens *(30 per SF)

Muyshondt CR2 Ion = *3/29 lumens

*Surefire KL1 (Luxeon) head = *29 lumens

*Gerber Trio (2 AA Lithium) = *22 lumens *(24 per Gerber)


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## MrGman

That is starting to look really good. I have just received my Malkoff M60, I will measure it at work first chance I get next week. I already have measured the M60F at a peak of 202 lumens. I have the SureFire 6P, I can put it in that and will again measure it in the Solarforce L2 with 1 extension and the 2X17500 batteries that seem to work so well. If you were going to get one of these or can borrow one that is another reference. 

If you have or can get a Fenix T1/TK10 I have measured those new at 225 lumens. Solarforce R2 single mode at 200 lumens max, no less than 180 lumens depending on how its mounted. 

the mag light LEDs for the 4 c/d cell with no head on it but just sticking the exposed LED into the sphere until I got a peak reading were no better than 50 lumens. This would be a good test because all of the light is coming out the side of the emitter's special lens, so if your sphere works well, it would collect all that light and integrate it to give you 50 lumens. 

I applaud your diligent effort :twothumbs to make it as accurate as possible and good for total comparative efforts.


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## precisionworks

> I applaud your diligent effort :twothumbs to make it as accurate as possible and good for total comparative efforts.



I appreciate you saying that. Your comments were my primary motivation to keep tweaking the design to get it as correct as possible.

Half-watt as caused me to test & retest the E1B ... it still gives readings that I consider extraordinary. But those readings are also supported by white wall shots & ceiling bounce meter readings - it is one bright light.

Using the correction or division factor of 18 produces lumen readings that closely correlate with most of the manufacturers stated outputs. I don't have any of the other lights you suggested testing, but I'll be happy to test any light that anyone sends, and I'll pay return shipping. I'd like to build as large a database as possible, but I currently have most every light that I want.


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## MrGman

Now that you have this data please put together this simple table of your measured Lumens readings versus the Vendor's stated Lumens. If its multimode list the mode (hi-med-low) on each individual line. Don't bother to list the lux readings as they are not useful in this quick comparison table. This will help to see how close your readings have come for those of us who are not familiar with some of those lights. As we build up the list of confirmed readings and the table grows longer we will see how good it is or if it needs further refinement.

But this really looks good. :thumbsup: :thumbsup: 

I am very curious how it will track from the low level to the brighter lights and whether or not the Incans versus LEDs show any differences. 

Since you have the 6P have you tried its normal incan light yet with good batteries? I think mine measured 50 lumens. Its another plot point to compare.

Even if you IS is not perfect, it will still be a much better total light measuring tool that will be effective for comparisons of various lights than other techniques. Readings from light to light, regardless of beam pattern should be more consistent for the various light types.

Now you should also consider building an exact duplicate and then testing that the readings are the same and figuring out the cost. Why you say? I am guessing that you will be able to sell it to one of these other guys who tests a boatload of flashlights and still have a boatload of flashlights available to test. If some one like Bessie Benny bought one and it was consistent and measured all those lights he had and got lumens readings to build a very large confirmed table set of readings, that would help everyone out.

You should give yourself a reasonable profit for your skills and labor that you put into it and don't let anyone make you feel bad about making an honest profit from your labor. You deserve it. :twothumbs

Of course if some of these guys are close to you they may want to come over and do a lot of testing with you and publish data out the wazoo. 

Keep up the good work. G


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## MrGman

I measured the new Malkoff M60 in the IS at work today using the Surefire P6 bezel. It measured 220 lumens and dropped down to around 216 as it was warming up. I would use these numbers to calibrate the constant for your sphere. I talked to my PhD Optical Engineer coworker/friend today about your project. He did say that what ever the correction factor is, it would be a constant and work across the board. So if it winds up being 18 or 12 or XX we should get good readings using that constant for all readings of high and low power lights. Assuming for a moment that your Malkoff M60 is within 5% of what mine reads and I have a feeling it is if not within 2%, then I would take the lux readings off of that when it is dead center in the opening and just at the entrance, then divide by 216 and that should be your constant. I find that if I push the lights into the sphere the readings go down and if I pull them back away from the edge of the sphere the readings go down. tilting it doesn't have much effect which should be normal. 

On a side note the M60F in the Solarforce deep crenalated bezel was down around 200 lumens. The bezel is blocking some of the light around the perimeter as it sticks out so far and the meter is sensing that small loss. So from now on all my pills will be read using the SureFire Bezel only.

I plan on sending you a Solarforce R2 5 mode pill to keep. I will take careful readings using 6 volts from 2 primaries as it doesn't like higher voltage, in the SureFire bezel, in high, med, and low mode. I will send you the readings and then send you the pill. Hang on to the pill as that will be your calibration reference unit when measured inside a SureFire Bezel with fresh primary batteries. May be a while before I can get this done, as I have some personal business to attend to but send me a PM with your mailing address if you want the pill. 

If ever your readings start to drift, you can use the pill. If the time comes where we question the pill you can send it back and I can double check it and then send it back to you. Your lux meter may drift over time as they are all want to do. 

Hows that for starters?


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## precisionworks

WOW!

I really appreciate all your effort. Work has kept me from replying to your first post, but I am also eager to get a 'calibration standard'. Industrial IS have a tungsten calibration light run from a constant voltage/constant current power supply.



> whether or not the Incans versus LEDs show any differences.


I noticed that all the regulated LEDs stay at a near constant light meter reading. I did poke the 6P incan into the sphere & immediately noticed a reading that decreased a little bit every couple of seconds (non-regulated hotwire, I suppose). Each light meter does have an individual spectral response curve, so some meters will read some lights at a different value. My ExTech EA31 manual says "Calibrated to a standard incan lamp at a color temp of 2856K".



> Assuming for a moment that your Malkoff M60 is within 5% of what mine reads


Readings are within 3% of each other:thumbsup: I think my 18 number is awfully close to correct.


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## MrGman

The filaments of an incandescent lamp give off infrared energy. As the heat builds up the visible light energy drops off a little bit ever so slowly on incans. So the lumens readings does come down, beside what battery voltage drop is going to do. 

I spoke to Gene Malkoff a while back. He doesn't actually have the equipment to measure lumens but goes by what some of his customers and vendors give him data on.

The M60 and F series LEDs, I am sure are capable of more than 235 lumens from the emitter, but with the optics in front of them, regardless of type there will be some loss of peak lumens. 

I measured a real diffuser that I was given and it was dropping the lumens down by 10%. The 6 degree optic is great but I am sure that the output is not at the original 235 lumens. My reading of 220 I believe is much closer to the truth. Especially when compared side by side to the Fenix T1 by eye and by the IS, the Fenix is just a touch brighter and its starts at 230 and drifts down to 225. As the phosphor warms up its efficiency does drop every so slightly. This will stabilize and if you are holding steady for a longer ready than the first 10 seconds its usually gone. 

Point is I think it would be good for now to assume your M60 is the same brightness as mine and use 220 lumens out to find your more finely tuned constant "correction factor number" and go with that.

I saw that you updated your previous set of numbers and it looks good. That one SureFire E1B measuring 130 lumens and rated at 80 is the only puzzling one. Are one of those numbers a typo? If not its always possible that what ever the controller components are supposed to be doing for regulation, it was set wrong or has a faulty component that it is allowing it to drive harder than what they had intended. Otherwise I would say that your baffle just isn't quite big enough and your positioning of the light is such that this one is still causing direct spill onto the photo detector some how.

by tilting the light at the input port the brightness should not really go up or down to any significant value since in theory the sphere is still collecting it all. If you find that your readings do change substantially, then the baffle is not large enough or in the exact best spot. 

Of course if all other flashlights are reading true to form once we have the final fine tuning "calibration" I would say ignore this one light and be glad to have it (as I think you already are). 

So I will try and take some readings of the 5 mode unit next week and send it out to you (provided you remember to pm with an address, but no rush). 

Also do you have the original incan lamp for the P6 to measure with a fresh set of primary batteries? 

and lastly, isn't it better to have a good feel for what the total light output is in lumens rather than a lux reading of the hot spot? 

Once you know what 100 lumens really is, its easier to understand that the new Malkoff 60 puts out 220 plus, or the Fenix T1 puts out 225 or that a small EDC light puts out 55 lumens and know what that really means??? :thumbsup:

This is really good. I would expect that some people will want you to measure their lights as the data is getting very close to what I would call trustworthy. 

:goodjob:


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## precisionworks

> That one SureFire E1B measuring 130 lumens and rated at 80 is the only puzzling one.


Same here, G. White wall shots, side by side, as well as metered ceiling bounce tests (4' to ceiling + 4' bounce back) show the E1B as brighter than the 120P, and almost the same as the U2. Other members have made similar comments in PMs to me. It is awfully bright ... I may send it to you to test in your sphere at work.



> tilting the light at the input port the brightness should not really go up or down to any significant value


Tilting makes no difference on any light ... there is a 'sweet spot' in the light tube that generates a max reading. Normally it's before the bezel of the light reaches the end of the tube, which projects just slightly beyond the inside of the foam wall.

I'll PM my address:thumbsup:


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## wbp

Very interesting discussion, I've been wanting to do this for some time. I own a 6" Hoffman IS, but it has a reference light source installed and I am reluctant to remove it for fear of losing the calibration.

This looks to be the same sphere as you used:
http://www.plasteelcorp.com/mm5/merchant.mvc?Screen=PROD&Store_Code=PCO&Product_Code=10072

They also have 8" and other sizes.

William


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## precisionworks

Good call on the link to plasteelcorp, that is exactly the one. Probably made by one foam molder & distributed by a dozen retailers. The 12" size works well, I'd try a larger one except that the larger sizes quickly increase in price.



> it has a reference light source installed and I am reluctant to remove it for fear of losing the calibration.


That sounds like the wise approach. I really would like to figure out a light source of known luminous flux, then build a regulated DC power supply to drive that bulb - probably what you have in your Hoffman. But the numbers generated in my IS do track closely (in most cases) with those from the manufacturers. IMO, this is a much better approach than a one meter reading of the hotspot, which tells only a small part of the total story.


----------



## wbp

precisionworks said:


> That sounds like the wise approach. I really would like to figure out a light source of known luminous flux, then build a regulated DC power supply to drive that bulb - probably what you have in your Hoffman. But the numbers generated in my IS do track closely (in most cases) with those from the manufacturers. IMO, this is a much better approach than a one meter reading of the hotspot, which tells only a small part of the total story.



Most reference light sources are incandescent, running on very well regulated moderate/low voltage so as to reduce the effects of filament wear, and to get them to output Illuminant A ( (x,y)=(0.44758, 0.40745) - around 2856 K). The problem is that inexpensive light meters will read VERY differently at Illuminant A, which is what they were calibrated with, than they will at 5400K or 6500K.

So even if you calibrated your setup with an accurate incandescent light source, you would not get accurate readings from an LED flashlight with any of the Extech or similar meters. You'd be better off with an LED reference, which shouldn't be too hard to build. Or just use a known LED flashlight with a regulated power supply...

To get accurate measurements at different frequencies you have to spend a LOT more than the price the meter you are using, the most accurate being a spectroradiometer (I own two).

William


----------



## precisionworks

That's an interesting point ... I really thought than an incan reference light would be better, but it makes sense to use a LED reference when all my lights but two are LED.

My meter instructions came with a spectral response chart, and it showed that the greatest response is not at LED color temp, but rather at incan color temp. The area under the bell curve appears to be 500nm to 600 nm. 



> use a known LED flashlight with a regulated power supply...


That sounds like the best plan.


----------



## MrGman

All that really means for your set up is that you would have to use a different constant number to divide the lux by once you had a known reference when using incans versus LEDs. 

They normally drive the filament with a constant current power supply where its ramped up to the desired value and held there to 3 digits behind the decimal point such as 1.000 amps. The current definitely changes with a constant voltage source as the filament gets hot and still drifts a little after it is hot. Can't hold constant current and constant voltage at the same time into the load. So constant current is best and let the voltage drop be whatever the load dictates. As long as you ramp it up slowly for things like a real filament its no problem. We have one in the optics lab for our reference light sources and the ones the engineers are testing. For instance we have a green LED array that is driven to 1.000 amps and makes 80 lumens. It is used to check the system whenver the engineer wants to or when it comes back from calibration each year. That is just one test sample they use. 

But since most of your testing will be LEDs, an LED light source would be best. I didn't have time to get readings on the one I am going to send you today, maybe tomorrow or Monday.


----------



## wbp

MrGman said:


> They normally drive the filament with a constant current power supply where its ramped up to the desired value and held there to 3 digits behind the decimal point such as 1.000 amps. The current definitely changes with a constant voltage source as the filament gets hot and still drifts a little after it is hot. Can't hold constant current and constant voltage at the same time into the load. So constant current is best and let the voltage drop be whatever the load dictates. As long as you ramp it up slowly for things like a real filament its no problem.



Incandescent lamp reference sources that I am familiar with adjust voltage, not current. A good one includes use a calibrated sensor to measure the lamp's output. The voltage determines the color of the lamp's output. The illuminance is adjusted by opening or closing a variable width slit.


----------



## wbp

Now that I look at them more I think the spheres from Plasteel are different. Those are styrofoam, which is coarser, vs. polystyrene from Barnard. I've got one of each on order so we'll see.

Some of the variation in your readings are going to be from the frequency response of the Extech meter.

Precisionworks, where are you located? I might be able to help you calibrate your meter against a spectroradiometer...

William


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## MrGman

Before I lose the data I measured my Solarforce R2 5 mode pill inside a Surefire 6P host with 2 new Surefire batteries. 

At high mode it came on at 160 lumens and settled in around 155 lumens.
in medium mode it came on at 87 and settled in to around 85 lumens.

in low mode it was 37 lumens. I will try and get it shipped to you tomorrow or next Monday, keep it as a reference.


----------



## precisionworks

> where are you located? I might be able to help you calibrate your meter against a spectroradiometer...


That would be neat, William. I'll PM my address info, location is 89 miles southeast of St Louis.

I'm happy to see that you have two spheres ordered ... I wondered if/when someone else would try this. Eager to see the reflectance difference between the two materials.

If I did this again, a baffle or baffles would be installed prior to boxing in the sphere.


----------



## Endeavour

Precisionworks: A bit of food for thought from my end - you may want to consider applying a coating of some kind (thick primer, an epoxy resin like Envirotex swirled around the inside), followed by a coating of highly reflective white paint (www.labsphere.com has very lambertian coatings, others may sell some as well), which may give you a nicer optical surface inside the sphere, as opposed to raw styrofoam.

Certainly nice work so far, and a big :thumbsup: to your efforts in obtaining more accurate light readings in a DIY fashion rather than simply accepting the constraints of the norm. 

-Enrique


----------



## McGizmo

I was told by one of the experts at one of the Sphere companies that in a pinch, the cheap Styrofoam coolers make a reasonably effective IS. In terms of materials, teflon seems to be a very good material for light reflectance and being easy to machine would probably be good for ports in an IS or as reducing collars in the port to keep the light "in". 

Be sure to confirm compatibility of a foam with any adhesive or coating! :green: Anybody ever mix up a batch of polyester resin in a styrofoam coffee cup!? (don't do it!)


----------



## MrGman

The integration spheres I have looked into at work do not have "reflective" white paint or coatings on the inside. It is a soft, I want to say non gloss, or "flat" white. It gathers all the light but you don't want actual close to mirror like reflections because that will bounce the hotspot into the photodetector and give false high readings. I guess I am trying to say you don't want the interior surface to be shiny, from what I have seen it should not be. Other than that as white as white gets.


----------



## Endeavour

Mr. GMan: Labsphere, the company I linked to, makes coatings specifically designed for use in integrating spheres, they have very low absorption rates, and scatter light very evenly; "reflective" was probably a bad choice of words on my part.

I'll second Don's warning and add that it's worth trying _any_ chemical to be used on something like this on a small and non-critical area first to verify compatibility. I've dissolved several things unintentionally in the past through chemical incompatibility. It is my understanding that most epoxy resins will not harm polystyrene.

-Enrique


----------



## wbp

Barnard says the polystyrene sphere halves can be painted. This makes me think that these might be a better choice for this.

Labsphere's 6080 coating would be a good choice. It's the same coating that is applied to the inside of my Hoffman sphere. It's not cheap though. Edmund Optics sells the Munsell coating, which is probably pretty close to Labsphere's:

http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1325

$250 for enough to coat 200 square inches. For a 12" dia sphere you'd need 2 bottles...

For what we're doing I'm not sure it's necessary though...

William


----------



## LuxLuthor

What a great collaborative topic, and major kudos to PrecisionWorks. Very great to follow this. 



wbp said:


> Most reference light sources are incandescent, running on very well regulated moderate/low voltage so as to reduce the effects of filament wear, and to get them to output Illuminant A ( (x,y)=(0.44758, 0.40745) - around 2856 K). The problem is that inexpensive light meters will read VERY differently at Illuminant A, which is what they were calibrated with, than they will at 5400K or 6500K.
> 
> So even if you calibrated your setup with an accurate incandescent light source, you would not get accurate readings from an LED flashlight with any of the Extech or similar meters. You'd be better off with an LED reference, which shouldn't be too hard to build. Or just use a known LED flashlight with a regulated power supply...
> 
> To get accurate measurements at different frequencies you have to spend a LOT more than the price the meter you are using, the most accurate being a spectroradiometer (I own two).
> 
> William


 
It was good to see them taken into account. I found this pdf useful in addressing wbp's LED vs. Incan point. This other general Integrating Sphere pdf from Labsphere is also a nice resource.



Endeavour said:


> Precisionworks: A bit of food for thought from my end - you may want to consider applying a coating of some kind (thick primer, an epoxy resin like Envirotex swirled around the inside), followed by a coating of highly _"reflective"_ white paint (www.labsphere.com has very lambertian coatings, others may sell some as well), which may give you a nicer optical surface inside the sphere, as opposed to raw styrofoam
> 
> -Enrique



Again, good to see the issue of surfaces (& baffle) being brought up for even more accuracy.



wbp said:


> Barnard says the polystyrene sphere halves can be painted. This makes me think that these might be a better choice for this.
> 
> Labsphere's 6080 coating would be a good choice. It's the same coating that is applied to the inside of my Hoffman sphere. It's not cheap though. Edmund Optics sells the Munsell coating, which is probably pretty close to Labsphere's:
> 
> http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1325
> 
> $250 for enough to coat 200 square inches. For a 12" dia sphere you'd need 2 bottles...
> 
> For what we're doing I'm not sure it's necessary though...
> 
> William



With his meter utilizing the CIE Photopic Spectral Response (380 - 780 nm), like you say an expensive paint designed to reflect a range of 200 - 2500nm seems a bit of overkill. 

I'm wondering about the quality and applicability of the sensor being used with specific narrow wavelength LED (still reading) and how well this sensor reads/converts various LED ranges to CIE Photopic Spectrum (based on defined 555nm green standard)--note section 3.2 in first LED pdf link. 

Then I'm also looking at the proper use of lux, lumens, watts in this scenario. Note summary in XeVision's page under section titled: 
"_*A comparison of the watt and the lumen illustrates the distinction between radiometric and photometric units*_" ​I was also noticing the specific designs this Edmund line has for LED measurements that go into various size I.S. Too bad this is all so expensive. 

I hope I'm not taking this too much off topic...again, really cool topic.


----------



## precisionworks

Enrique, I had thought about coating the inside of the sphere, but thought that the first one, in raw polystyrene, would be a good reference. My first sensor port was a simple hole bored through the sphere wall - the high reflectance of the cut foam + lack of baffle gave inflated readings. Then a tube (painted flat black inside) was installed, which gave undervalued readings. That was removed & replaced with a tube painted flat white inside, with a 45° slant cut to shield the sensor ... which worked out the best so far. My reflectance is still below optimum, as the radius squared correction factor is 25, but the actual factor is 18. Which doesn't bother me, considering the cost of the Munsell coating



> teflon seems to be a very good material for light reflectance


Don, PTFE, and probably a number of other plastics (like HDPE) would make a nice, optically 'soft' surface. I don't know where to purchase these in sphere form, but they would be rigid enough to need no external support box. Split in half & hinged like a commercial sphere, the 'innards' could be configured differently ... like putting the source light inside the sphere, shining directly at the baffle, with the photodetector location behind the baffle. 

Your idea for machining reducing ports is great, and I have some scrap HDPE solid round that will work. Just need to make one for each diameter light, or figure out sizes so that they can nest inside one another.

LuxLuthor, thanks for those links! Even with reading pages of information on spheres, the first Labsphere article never popped up, even though I'd read the second one.



> I'm wondering about the quality and applicability of the sensor being used with specific narrow wavelength LED (still reading) and how well this sensor reads/converts various LED ranges to CIE Photopic Spectrum


That has concerned me from Day One. General purpose (inexpensive) light meters are heavily biased to look at all light & read out the 'sunlight equivalent'. The spectral response of these meters is much more attuned to the incan portion of the spectrum vs the LED portion. If both incans & LEDs were tested side-by-side, the results would probably be unacceptable using an identical correction factor. But a correction factor for incans could easily be developed that would allow dual use.

I believe that the Edmund design would not be terribly expensive to build in the home shop ... the challenge is to find a CCD array (Charge Coupled Device, like a digital camera sensor) that reads only the 360nm to 1000nm spectrum. Either there are limited spectrum CCDs, or optical filtering is used to allow passage of only the desired wavelengths. Linear CCD Array Cameras, like the LARRY 2048 (Linear ARRaY 2048 element) are available, but couldn't find a cost.



> I hope I'm not taking this too much off topic ...


I appreciate your input. If it wasn't for half-watt & MrGman, this design would have stalled early, and been of limited use. Now, with William building his versions, there will be a basis for comparison. Which is really neat


----------



## precisionworks

RE: constant current vs constant voltage, this is from the first link that LuxLuthor posted, in Section2.2.1:



> In the lab, LEDs are usually operated in a forward bias direction from a constant current DC power supply. At low currents, the slope of the radiant power (luminous flux) verses time rises faster than the slope of the electrical power (start-up range) verses time. At high currents, the slope becomes flatter (saturation area), which is mainly caused by heating of the LED chip. Under normal operating conditions (between the start-up range and saturation area), the optical radiation emitted by LEDs is strongly correlated to the electrical current, which is why constant current is recommended for measurements intended to characterize the optical properties of an LED.


----------



## wbp

precisionworks said:


> I believe that the Edmund design would not be terribly expensive to build in the home shop ... the challenge is to find a CCD array (Charge Coupled Device, like a digital camera sensor) that reads only the 360nm to 1000nm spectrum. Either there are limited spectrum CCDs, or optical filtering is used to allow passage of only the desired wavelengths. Linear CCD Array Cameras, like the LARRY 2048 (Linear ARRaY 2048 element) are available, but couldn't find a cost.



The Edmund instrument referred to uses a CCD Spectroradiometer (or spectrograph) to measure the light. (Note also that it also uses an integrating sphere if the light being measured is an array or larger than the specified size.)

This instrument does not use limited spectrum CCDs or filtering. It uses a diffraction grating to spread the light out into a known spectrum. Each column of the CCD array receives light from one frequency band. The CIE Color Matching Transforms are then applied to compute the levels of Red, Green, and Blue. The math to calculate x,y coordinates and Luminance values from there is straight forward and well documented.

You could build one (I have) but it's not cheap, and you still need to calibrate it. I built mine from a Shelyak Instruments spectrograph (about $3500 with calibration reference built in) and a Quantum Scientific Camera ($5000). It's quite comparable to my Gretag Lightspex and much more sensitive. I already owned the QSI camera, which I use in my business, and I use the Shelyak for astronomy as well. Otherwise doing this is not very cost effective...

Processing the data from the CCD array is also not trivial. The data will be numbers representing the light of each spectrum band, but the bands will be arbitrary. Most instruments use a windowing algorithm to compute the 5 nm bands needed for the CIE Transforms (or 1 nm if you want to go to that level of accuracy but that would be overkill for most uses). Once that's done the rest is, as I said above, pretty easy.

The camera also has to be calibrated for background noise (Dark frames) and uniformity (Flat Field). Dark frames are easy, Flat Fielding is not. The QSI camera I use is very new, and has a Kodak chip guaranteed to 1% uniform and actually measured better than 0.5%; this is good enough that we don't really need to worry about it. Normally such a chip comes in a camera costing about 50% more than I paid but QSI had a run of Class 1 chips at Class 2 prices, so I lucked out. (The current generation of scientific CCD chips from Kodak are amazing.)

I don't think you want to use a linear CCD array - isn't that a single row of pixels? That would have very low sensitivity.

William


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## precisionworks

> isn't that a single row of pixels?


It is, as the photo above shows.

Talk about speaking before you understand the problem, I grossly underestimated the effort required for a limited spectrum meter

That's OK, since I only slightly underestimated the work required to get the IS to function properly


----------



## LuxLuthor

I think one of the most useful things about this thread is it begins to expose the standards & requirements for accurate descriptions & measurements. This has been rarely exposed in the many threads where Meterman LM631's & other CIE Photopic Spectral meters are used with impunity, and as accurate source information regarding LED Lux, Watts, & Lumens.


----------



## wbp

OK, don't laugh - saw this in my local Leslie's Pool Supplies. It's a sphere, all white inside, in two pieces with hinges. Hmmmmmm....

http://www.lesliespool.com/browse/H...-Cooler/D/30100/P/1:100:10000:1000010/I/43645

William :tinfoil:


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## wbp

OK, don't laugh - I was in my local Leslie's Pool Supplies and saw this - it's a sphere, with all white liner - hmmmmmmmm...

http://www.lesliespool.com/browse/H...-Cooler/D/30100/P/1:100:10000:1000010/I/43645

I suspect this one might be too reflective, but it's intriguing...

William :tinfoil:


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## wbp

An interesting article about an alternative to an integrating sphere:

http://www.laserfocusworld.com/disp...s-serve-as-alternatives-to-integrating-sphere​


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## precisionworks

I like it ... no boxing needed, and one light port already installed

Good article on the baffled tube.


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## wbp

*update on the styro spheres*

I now have styrofoam spheres from both Barnard and Plasteel. In spite of their different descriptions I cannot see any difference, both appear to be ordinary styrofoam just liike what you would see in a cheap cooler. I was told that "polystyrene" was a smooth styrofoam, but apparently that's also what Plasteel is selling.

Warning: Barnard's 10" sphere is not completely hollow inside, it has flat areas at the end, apparently for strenght, but this makes it unsuitable for our purposes.

I got an 8" sphere from Plasteel which looks very promising. I'm going to start with that.

I just HAVE to pick up one of those beer coolers to try. I really suspect it will be too reflective, but if it doesn't work out, I can always use it for what it was intended for in the first place... 

William


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## wbp

Inspired by Precisionworks, I built a 12" Isphere using a styrofoam ball. I've uploaded a picture here:
http://www.meier-phelps.com/temp/IMG00024r.jpg

The instrument is a Gretag Lightspex spectroradiometer, current calibration, using the fiber optic probe with cosine receptor attached.

Here are my first pass results, readings are in Lux:

Fenix L0D Q5 Hi 5803 
Muyshondt Aeon Hi 10814 
Lummi Raw NS Hi 22404 
Bitz Pocket Hi 10984 
Olight T10 Hi 13545 
Nitecore Defender Hi 11446 
Nitecore EX10 Hi 14620 
Jetbeam II IBS Hi 17975 
Milkyspit Creemator Hi 27396 
Dereelight DBS V2 - 17970 
MTE SSC P7 Hi 40874

If I divide by pi * radius**2, I get the following Lumen readings:

Fenix L0D Q5 Hi 74
Muyshondt Aeon Hi 128
Lummi Raw NS Hi 285
Bitz Pocket Hi 140
Olight T10 Hi 173 
Nitecore Defender Hi 146
Nitecore EX10 Hi 186
Jetbeam II IBS Hi 229
Milkyspit Creemator Hi 349
Dereelight DBS V2 - 229
MTE SSC P7 Hi 521

To me, most of these seem to be within range of what I would expect, except the little Lummi Raw NS. The Fenix and the Jetbeam are spot on. The readings are repeatable to better than 2%.

I repeated the test, this time with the fiber optic probe without the cosine receptor. Readings are in cd/m2 (candela per meter squared). 

Fenix L0D Q5 Hi 1915
Muyshondt Aeon Hi 3520
Lummi Raw NS Hi 7430
Bitz Pocket Hi 3617
Olight T10 Hi 4944
Nitecore Defender Hi 3932
Nitecore EX10 Hi 4845
Jetbeam II IBS Hi 5620
Milkyspit Creemator Hi 9180
Dereelight DBS V2 - 5800
MTE SSC P7 Hi 14394

Divide by radius squared to get lumens:

Fenix L0D Q5 Hi 77
Muyshondt Aeon Hi 141
Lummi Raw NS Hi 297
Bitz Pocket Hi 145
Olight T10 Hi 198
Nitecore Defender Hi 157
Nitecore EX10 Hi 194
Jetbeam II IBS Hi 225
Milkyspit Creemator Hi 367
Dereelight DBS V2 - 232
MTE SSC P7 Hi 576

These are consistent with the first set. Changing angle of flashlight does not change reading significantly. No baffle, but I'm considering adding one.

The opening in my sphere is not quite large enough for the DBS to fit, so it's resting on the outside. It's such a narrow beam I'm not sure how much this matters. I'm reluctant to make the opening larger just for this one light.

This is fun! But I've got to get back to real work now... :twothumbs

William


----------



## MrGman

Some of the numbers seem a little high to me for through the front lumens. Especially the DBS that doesn't fit into the sphere opening. You would be surprised at how fast the numbers fall off when I pull the flashlights away from the port by only 1/4 inch and those are ones that do fit inside. 

When you get a chance can you post what the vendor's published lumens ratings are for each of those lights next to your numbers for comparison for those of us who aren't familiar with each of those models. 

Also I don't suppose you got a picture of what the detector port area looks like with your detector at the port? 

However, in general this also looks great and I am sure we can get it in tune with others. Its too bad you don't have a Fenix T1 to measure because I know that they read 230 lumens at turn on and about 225 real through the glass lumens on a good set of batteries when warmed up. 

Your making this look too easy.


----------



## wbp

The DBS is supposed to be 210 lumens in this configuration, so that's pretty close. The opening is just barely too small for this one, most if not all of the actual light coming from that reflector is getting thru.

The Fenix is supposed to be 75, and the Jetbeam 225 on hi, so those are damn close.

I don't have time to dig up ratings for the others now, sorry.

Still scratching my head over the Raw NS - I knew it was bright, but that's a lot higher than the rated 160. It also gets hot pretty fast.

"easy"? Don't forget I'm starting with a $9000 instrument. Paying for that wasn't exactly easy (although it has paid for itself many times over since I bought it).


----------



## MrGman

I said you were making it "look" too easy. And definitely in regards to building a sphere and just throwing an existing meter into it that's true, since you didn't just run out and buy the $9K meter for this. But since you have a $9K meter on hand all the more better. (Take it as a compliment by the way, that's what it was )

However you readings are still on the high side of vendor specs. I am guessing that the baffle really needs to be in there to chop down some of that reading. The only flashlight that I have seen so far actually meet published specs was the Fenix T1 which they say has double sided AR coatings on the lens. My Fenix L2DQ5 doesn't have 180 lumens out the front, its more like 150. 

The Malkoff M60 and M60F may be 235 lumens without a flashlight host's lens in front but what I measured from my Surefire 6P host was 220. So I am guessing that the DBS should not be reading 229 or more.

Just trying to help you fine tune it, it is very close, but I would still be more conservative knowing that the baffle isn't there. 

It will be very interesting to see what precisionworks comes up with for the pill I gave him.


----------



## wbp

I'm not claiming that this setup is perfectly accurate by any means, but I do think the results so far are encouraging. I worry though that the primary issue is the quality of the reflective surface (styrofoam). There's a reason that they make spheres out of Spectralon or coat them with barium sulfate. It's quite possible that the reflectivity of our styrofoam ball will never give accurate readings for different types of flashlights without adding a coating. It's tempting to order some coating from Edmund and try it, but if their coverage specs are correct, it will take $1000 worth...

I just bought an L1T on eBay so when I get that I can see how it measures with this setup.

I've got some thin styrofoam sheeting - I'll make a small baffle and hot-melt that in place and see what that does, but from what I can see there isn't any direct light falling on the sensor probe. While I've got it opened up I'll take a couple of pictures of the inside. I'm adding a white PVC fitting for the sensor port to keep the probe placement consistent. It's threaded so I can change the sensor fittings as needed. I drilled out the inserts to hold the sensor snugly. The sensor itself is installed such that it is flush with the inside surface of the sphere. It has to be easily removable though because every time the Lightspex changes ranges I have to conver the probe to take a dark frame (Lightspex does not have a shutter). My lab is capable of total blackout though (which is not trivial), so in that case I can do dark frames with the probe in place.

This is actually leading to something I've needed in the lab for some time - the ability to accurately flat field my CCD cameras. The 12" sphere is large enough for the smaller camera; once I've got the kinks worked out I'll order a larger sphere for the big QSI camera.

William


----------



## MrGman

Yes this is encouraging. You answered my question about the sensor being flush to the inside wall of the sphere housing, that's what I wanted to see in the pics. 

Tell my you don't have a Malkoff M60 or M60F? How can this be? Especially when they have been on sale all month. 

Now all we need is to see Precisionworks update with the pill I sent him.


----------



## wbp

MrGman said:


> Tell my you don't have a Malkoff M60 or M60F? How can this be? Especially when they have been on sale all month.



Well, for one thing I don't have anything it will fit in, at least according to Malkoff's web site: "It was designed specifically for use in SureFire 6P, 6Z, C2, M2 and G2 flashlights." So what would I do with an M60 if I had one?

The only Surefire light I have is the E2E with a Milkyspit head, which is a killer flashlight. In general I find the Surefire lights overpriced for my tastes.


----------



## MrGman

I concur which is why I have at least 4 of the Solarforce L2 hosts and various extension tubes. The L2 host at most is only $25 on Lighthound. The Malkoff's however are worth every penny, they are great.


----------



## precisionworks

Funny that my ears have been burning all evening, as I ran 18 sets of tests with the pill that GMan sent (six pair of new SF batts, three light level readings per pair). Using his baseline readings, my earlier lumen calculations were 18.2% too high. I edited post #21 in this thread to reflect these corrected readings.

William, your sphere setup is much too simple & too easy to modify I really like your approach, and appreciate the effort it took to generate the readings.



> The Malkoff's however are worth every penny, they are great.


+1

A 6P plus an M60 is an awesome light for night time walks, especially with the 2-stage mod from Wayne. About $100 and a great value. I expect my P7 Mac will blow it away, but it should for three times the cost.


----------



## wbp

Gentlepeople, I have installed a baffle, and the results are, I think, very interesting. First of all, a couple of pictures, showing the baffle and the sensor port:

http://www.meier-phelps.com/temp/IMG00025.jpg
http://www.meier-phelps.com/temp/IMG00026.jpg

I admit, the baffle is a bit of a hack, not exactly round, but I was in a hurry. The black ring in the sensor port is a bit of rubber fuel line, it hold the tip of the fiber optic probe very nicely.

Now the measurements (cd/m2, CCT in K, calc'd Lumens):



Code:


[FONT=Fixedsys]Fenix L0D Q5         Hi   2051  5455K    82
Muyshondt Aeon       Hi   3219  5077k   129
[/FONT][FONT=Fixedsys]Bitz Pocket          Hi   3252  6080K   130
[/FONT][FONT=Fixedsys]Nitecore Defender    Hi   3387  6213K   135
[/FONT][FONT=Fixedsys]Nitecore EX10        Hi   4220  5739K   169
[/FONT][FONT=Fixedsys]Olight T10           Hi   4455  6147K   178
[/FONT][FONT=Fixedsys]Dereelight DBS V2     -   5380  5633K   215
[/FONT][FONT=Fixedsys]Jetbeam II IBS       Hi   5522  6048K   221
[/FONT][FONT=Fixedsys]Lummi Raw NS         Hi   6688  6409K   258
[/FONT][FONT=Fixedsys]Milkyspit Creemator  Hi   7674  6577K   307
MTE SSC P7           Hi  11490  5674K   460
[/FONT]

(The Fenix has freshly charged batteries)

I can repeat measurements and get within three percent. For example:



Code:


[FONT=Fixedsys]Bitz Pocket          Hi   3332  -----   133    2.2%
Muyshondt Aeon       Hi   3291  -----   132    2.2%
[/FONT][FONT=Fixedsys]Olight T10           Hi   4580  -----   183    2.8%
[/FONT][FONT=Fixedsys]Jetbeam II IBS       Hi   5675  -----   227    2.8%
[/FONT]

Some of this error is due to the Lightspex recalculating dark frames every time it changes ranges. I'm being lazy and just covering the light being tested, and not actually pulling the probe and covering it...

These numbers look really good to me. I've got a Fenix T1 coming so I can check that.

At some point I want to do a run with a more affordable meter like one of the Extechs (I have a 403125 here) and see if I can calibrate that to get the same readings. If I can, then we could actually build these for a very reasonable price.

Other than that I think I'm done unless someone can point out something I'm missing. What fun!

William


----------



## precisionworks

Impressive results, William

You tabulation makes it easy to read all the data that was collected.



> I think I'm done unless someone can point out something I'm missing


The only other thing that I've done (actually just started) is to measure mA draw of each light. There is quite a lot of difference in drivers/converters ... some keep the current draw dead constant, others run almost a sinusoidal range of values while keeping the lumen output steady. 

Another observation is that most any SureFire CR123, either single or in pairs, makes almost no difference in lumen level - again this depends on the driver/converter. New batteries generate the same levels as those that have seen weeks of use, at least in my limited testing. Most runtime curves show nearly level lumens until the end, so this should be no surprise - but I thought a new battery would have some impact.


----------



## wbp

precisionworks said:


> Impressive results, William



Thanks! You're work inspired me to even try this...



precisionworks said:


> Another observation is that most any SureFire CR123, either single or in pairs, makes almost no difference in lumen level - again this depends on the driver/converter. New batteries generate the same levels as those that have seen weeks of use, at least in my limited testing. Most runtime curves show nearly level lumens until the end, so this should be no surprise - but I thought a new battery would have some impact.



I agree current measurements are interesting, but it can be difficult to measure on some of these lights. I've had to build all kinds of sleeves etc. Don't have the time for that right now.

I've also noticed how well regulated (or not) some of the lights are. The Creemator, for example, is rock solid. The Lummi Raw NS output drops steadily in high, but that's not a big surprise given what it's putting out and how hot it gets. I need to ask Rob if it might be broken, the specs are 160 lumens and it's putting out 260. It's much easier to see this with the a meter that reads continuously, like the Extech, rather than the Lightspex.

William


----------



## cave dave

One thing to keep in mind is production tolereances of actual finished lights. I suspect if you had 10 Nitecore D10s (or any other production light) to test you would find a 20% or more difference in max brightness.


----------



## TexLite

First let me say Great Thread,this is one of the best reading and informative threads to come through CPF in a while.I have followed it with high interest.

I built a homemade lightbox a year or so ago,and have been very pleased with the results,though it was not nearly as impressive.It was put together very quickly and rather sloppily because I was unsure of the outcome,and didnt want to spend too much time if it didnt work.

I have mine very close,within 5%-7%,I believe.SSC P4 USWOH's from Fred
have all measured 240-250 @ 1000ma.A Surefire 6PL starts out around 100,but drops off after a while,which I think is correct because if you look at Chevro's runtime chart,it drops off after about 1/2 hour and remains fairly constant for the life of the batteries.

May I make a suggestion?

MrGman,I am assuming you have a CC power supply near the IS you have access to...
precisionworks,do you have access to one?The reason I ask is this,I would be very happy,if you guys were willing,to put together a few bare emitters on heatsinks to wire up and test output.I could cutdown a Mag into 5 or 6in sections and mount the LED's on H22A heatsinks,with a Deans plug or similar coming out the back to make the connections quickly.The LED's would be a Cree XRE R2,SSC P4 USWOH and P7 CSXPI.Also,maybe a well regulated torch.If you guys dont want to go through the hassle I understand.Even passing around a well regulated light that MrGman had tested would be extremely helpful.

Thanks,
Michael


----------



## wbp

precisionworks said:


> A 6P plus an M60 is an awesome light for night time walks, especially with the 2-stage mod from Wayne. About $100 and a great value. I expect my P7 Mac will blow it away, but it should for three times the cost.



Well, the Milkyspit Creemator is all of that too, it's my hands down favorite for total output, color, and throw. It was, however, quite a bit more than a 6p/M60. I'm find that I really like being able to choose the light level, I think I'd miss that with the M60. That said, I ordered one and an L2 from Lighthound so I can measure it... Gonna big a big sale on B/S/T when I'm done with this project!

It would really be interesting to measure the same light on both our spheres and MrGman's commercial IS. Is there something we can pass around?

William


----------



## MrGman

"It would really be interesting to measure the same light on both our spheres and MrGman's commercial IS. Is there something we can pass around?"

You can start with a bottle of 60 year Scotch, send it my way and I can see what I can do for you? 

I gave my R2-5 mode Pill to Precisionworks to keep as his source reference. If he wants to share it with you and then you send it back to him when you are done with it, its up to him.

Do you have a precison power supply in the 3 to 5V range that can put out up to 1 amp in a precise manner? I may have something else for you but it will take a while to get going.


----------



## wbp

MrGman said:


> You can start with a bottle of 60 year Scotch, send it my way and I can see what I can do for you?



I don't have anything that young (see my sig).


----------



## cy

precisionworks... here's an offer that should get your interest. 

a year or so ago.. silverfox and don co-sponsored a pass around for a set of lights to folks that had identical Meterman LM631

we all measured the same set of lights, which then were sent to a lab with an integrating sphere. 

these lights became calibration standards in their own right. we got to see how each LM631 reacted to the same set of lights. 

my meterman that took part in this pass around is available to you. 
please PM if interested...


----------



## wbp

Are any of the lights available?


----------



## MrGman

TexLite, yes I have a constant current power supply. I was thinking of putting a LED chip on a copper or Aluminum substrate disk that can simply be held up at the port and taken to a couple of obvious current settings like 0.350A and 0.750A, if its a good heatsink than 1.0000A. 

We simply get heat sink cubes and put the LED substrate on the front of that and have holders to hold it at the port. 

So yes we could do something along those lines I will pm my address to you. 

Wbp I am not impressed with you craftsmanship but definitely impressed with your greater than 60 year old scotch, I will be even more impressed when you send me a bottle.  Oh, and I am also impressed with the final results which is all that matters. Your DBS V2 coming in at 215 lumens is very close to what I predicted it should be based on the corrections made to precisionworks final numbers once I gave him the calibration standard R2-5 unit. 

I have heard of these Milkyspit units but am not really familiar with them. Give us a little elaboration on what that unit is, what it cost, what it runs on etc. And then the MTE SSC P7 also. :twothumbs great work.


----------



## wbp

MrGman - tell you what, next time I see you I'll share some with you. But I ain't shipping it anywhere! I bring it back personally when I go over for work.

Here's one thread on the Creemator:
https://www.candlepowerforums.com/threads/189777

In that review he says 900 ma on hi. Mine does something like 1250 ma on hi on a pair of CR123's, might be a newer one. Not cheap - you start with an SF E2E or E1B or the like, add a KL1 or KL2 head, then send it to Milkyspit to have it modded. Regulation is outstanding, color is excellent, almost perfect d65. 4 output levels.

The MTE is a cheapie ($45) from DealExtreme which I picked up used just to play with. It has no regulation, a huge reflector, and a tight beam. Uses a P7 (4 chip) LED.

ps: craftsmanship? you don't like gaffer tape? no time for that until after CEDIA. besides, I like how it looks - I can hang it from the ceiling and call it a mobile when it's not being used to measure flashlights!


----------



## orb

:wave: William


Wow 260 Lumens, you sure got a high flux Cree there. 
There is no fault with your light, when running on high the Raw NS will become warm after a few minutes.
This is normal & the nature of a light this size & bright. If your holding the light it does assist on cooling as your hand will act as a larger heat sink.
I am impressed with your simple yet effective styro sphere this whole thread made for very interesting reading. :thumbsup:
Out of interest what lumens do you measure on low? If you have the time.
I have not long since adjusted the lumens on high on our web site to 200 mainly due to now supplying with the R2 LED.
But it is nice to see that the actual lumens could be quite a bit more.

What I did see that is interesting is the higher the colour temperature the higher the lumens seems to be.
Do you agree with this?
My main reason for interest here is because at the moment the warmer bin LED's seem to be more popular. 
I wonder if there is a big gap in Lumens this will stay the case?
:thanks: Rob


----------



## cave dave

orb said:


> ...
> What I did see that is interesting is the higher the colour temperature the higher the lumens seems to be.
> Do you agree with this?
> My main reason for interest here is because at the moment the warmer bin LED's seem to be more popular.
> I wonder if there is a big gap in Lumens this will stay the case?
> :thanks: Rob


 A warmer color temp is caused by a thicker layer of phosphor on the die, but that thicker layer blocks more light, so output should be less. Might read different on a lightmeter though.


----------



## precisionworks

> I would be very happy,if you guys were willing,to put together a few bare emitters on heatsinks to wire up and test output.


That would be great. I wonder if my RC battery charger would work ... it's the DN G2Plus. If not, it shouldn't be hard to build a regulated supply that would be good for 1000 mA, and I'd gladly do that.



> I gave my R2-5 mode Pill to Precisionworks to keep as his source reference. If he wants to share it with you and then you send it back to him when you are done with it, its up to him.


Sounds like a good idea - PM your address info & I'll send it out. MrGman does caution to run this pill only on primaries, and that Li-Ion will kill it instantly.



> the higher the colour temperature the higher the lumens seems to be. Do you agree with this?


I do. This is probably a function of my meter, and most other lower cost meters - they are calibrated for daylight color temps, and warmer LEDs are closer to this than are the cooler ones.



> at the moment the warmer bin LED's seem to be more popular. I wonder if there is a big gap in Lumens this will stay the case?


The McGizmo SunDrop is currently the state of the art in high CRI lights, using the Nichia 083 emitter. I measured 640 mA to make 46 lumens (the buck/boost converter changes that to 350 mA at the pill) and that is the price you currently pay for high CRI. As these continue to develop, you should see more output with lower current draw. When the US Government eliminates incans, which is coming soon, there will be a major effort for warmer or color corrected LED lighting - there's not a woman in the world who wants put on makeup using an unflattering light source


----------



## orb

cave dave said:


> A warmer color temp is caused by a thicker layer of phosphor on the die, but that thicker layer blocks more light, so output should be less. Might read different on a lightmeter though.



Makes sense :twothumbs

PW: It is an interesting shift to the warmer colour temperatures we are seeing with LED's.


----------



## wbp

orb said:


> Out of interest what lumens do you measure on low? If you have the time.
> 
> What I did see that is interesting is the higher the colour temperature the higher the lumens seems to be.
> Do you agree with this?



Rob,

I just measured my NS on low - I got 20.2 lumens, fresh charge on the battery. I also did some tests on high: 264 lumens at turn on, 233 after 60 seconds, 231 after 60.

I'm not sure I agree completely about color temp and higher output - look at the two Nitecores in the table. However, it does seem possible that to get the temp lower that there is an added layer of filtering, and this would reduce the output.

I prefer 6500, or more accurately D65, I really don't like the "warmer" color emitters. Part of this I'm sure is because of the business I'm in... 

I also measured the Creemator's 4 levels, with fresh batteries: 2.6, 36, 114, and 339. That's quite a range!

And speaking of color temperature, does anyone here know why it's really meaningless? :devil: 

William


----------



## TexLite

orb said:


> What I did see that is interesting is the higher the colour temperature the higher the lumens seems to be.
> Do you agree with this?
> Rob


 
Rob,

Thats correct,for the most part.If you look at the binning for all major LED manufacturers max luminous flux available increases as color temp increases.
Cree MC-E for example:
Cool White 5000k-10000k 790lm max
Neutral White 5000k-3700k 650lm max
Warm White 3700k-2600k 605lm max
The reason is the way the phospher converts blue to white.

Thanks,
Michael


----------



## wbp

precisionworks - a question: how do you have the meter probe attached to your sphere? In my tests I found that it was very important to have the sensor flush with the inside of the sphere, otherwise it picks up light from the styrofoam around it. I wonder if you did this if you wouldn't get better results.

William


----------



## precisionworks

William,

An excellent question, as it took three attempts to get that part right.

The first readings (very high) had the sensor probe atop a short tube, with the diameter of the sensor just fitting inside the tube. The total wall thickness of the sphere was directly below the tube, and it gathered light like there was no tomorrow. Not so good.

The short tube came out & was replaced with a longer tube that extended slightly below the inside of the sphere. Flat black spray paint was applied to the inside. Those readings came out far too low.

MrGman brought up the baffle idea, which I'd seen on the commercial sphere websites. Since my IS is a 'sealed unit', any modification had to be done without opening the IS. After considering different approaches, I decided to cut another tube at a 45° slant. The long point of the tube end faces the light port, so that the point provides shadowing for the inside of the tube. Flat white paint was used this time. The readings now are close ... my correction factor is 22, an ideal sphere would have a factor of 25 (using a 5" radius, squared). This is the setup currently in use.


----------



## MrGman

I spend 40 minutes during lunch writing up a big dissertation on how to solve this and most of the problems in the universe and when I clicked "submit" it all got lost.  Got an error message and no post. :mecry:

Not writing it all again. 

If you guys want to get different colored LED sources and/or the Malkoff M60F or LF heads, I can test them and then you can have them back and see how well your units read the colors and if they are consistent. Decide on what it is you want and both get the same models so you can do head to head comparisons after I check them on the master IS. We can try and find from other people sending their light meters to you for comparison which ones work the best. I am sure that there is a reasonable meter out there that will work for most of what we are doing and getting good results, especially since we have come so far with believable readings from precisionworks unit so far.


----------



## mcmc

wpb - nice work on getting that IS made. Interesting results, didn't expect the Creemator to blow away everything there! Milky did a great job. Glad you like it by the way =)

Now I'm tempted to ask you folks if you'd be willing to let me ship some of my lights over to find out some real lumens values on these bad boys =)


----------



## wbp

Hey, I'm happy to measure anything you want to send my way! Oh, did you want it returned too??? 

Seriously, within reason I don't mind doing this, as long as it isn't too much of a hassle sending them back. That generally means Fedex for me, I dislike going to the post office.


----------



## mcmc

Hehe, that'd be a sweet deal now wouldn't it? =D

Cool, appreciate the offer! May end up sending a couple lights your way...how much is FedEx usually, for say a 2~3lb package?


----------



## Aluminous

mcmc said:


> how much is FedEx usually, for say a 2~3lb package?



Here's what their websites seem to say are the estimates for shipping a 3lb package within the US:

Fedex: $8.51 for ground 3-5 day, $26.17 for 2-day air
UPS: $11.43 for ground 3-5 day, $30.28 for 2-day air
USPS: $7.22 for parcel post (~6-day), $9.55 for priority mail (~2-day)


----------



## precisionworks

Another option to consider is USPS Priority Mail. Sometime 2-3 day delivery, sometime 3-4 days. Tracking number included in price, just like UPS & Fedex. Up to 1# for $4.80, and they provide free cartons in a variety of sizes.

USPS really rocks on dense, heavy items that will fit inside their Flat Rate Carton. Up to 70# for $9.80


----------



## wbp

precisionworks said:


> Another option to consider is USPS Priority Mail. Sometime 2-3 day delivery, sometime 3-4 days. Tracking number included in price, just like UPS & Fedex. Up to 1# for $4.80, and they provide free cartons in a variety of sizes.
> 
> USPS really rocks on dense, heavy items that will fit inside their Flat Rate Carton. Up to 70# for $9.80



Sorry, but USPS tracking is a joke, it's nothing like Fedex. No info until the item is delivered, if then. Fedex tracking shows where an item is and when it will be delivered, accurately.

I've no objection to Priority Mail if they'll pick up the return package. If I have to go to the local post office that's at least 1 hour waiting in line, compared to 2-3 minutes at Fedex. I just don't have the time!


----------



## precisionworks

The tracking isn't the greatest as the package is on the way, but they send an immediate email to the sender as soon as the package arrives at the destination. I've never taken a package to the Post Office (except International that needs insurance) - as soon as the Click & Ship label is printed online, you request carrier pickup & it's all done.

Of the 200+ packages sent USPS (eBay sales) none were ever lost or damaged.


----------



## wbp

Some new measurements...

(cd/m2, CCT in K, calc'd Lumens):



Code:


[FONT=Fixedsys]Fenix L1T            Hi   2697  6041K   108   Energizer Lithium[/FONT][FONT=Fixedsys]
Fenix L1T            Hi   2594  6025K   104   Alkaline
[/FONT][FONT=Fixedsys]Fenix L1T      [/FONT][FONT=Fixedsys]      Lo    514  5734k    21

[/FONT][FONT=Fixedsys]Lumapower Avenger    Hi   2628  5321K   105   10440
[/FONT][FONT=Fixedsys]Lumapower Avenger    Lo    686  5039K    27
[/FONT][FONT=Fixedsys]
L2/Malkoff M60       --   7031  5908K   281   2xCR123
[/FONT][FONT=Fixedsys]
(repeats for measurement reference)
[/FONT][FONT=Fixedsys]Jetbeam II IBS       Hi   5485      K   219
[/FONT][FONT=Fixedsys]Milkyspit Creemator  Hi   7972  6544K   319   2xCR123
[/FONT]


----------



## precisionworks

William,

The M60 reading seems quite a bit higher than what MrGman showed (220L). Malkoff's site shows it as 235+L, and I believe he is measuring bulb lumens without losses for a lens ... which makes the 220L figure seem about correct. To what do you attribute your higher readings?


----------



## MrGman

Is the L2/Malkoff M60 readout 201 lumens or 281 lumens? Was that a typo? As much as I love the Malkoff M60 I can't believe its 281 lumens. Especially if you are using the solarforce L2 as a host because the longer crenellated bezel obstructs some of the spill of the light to reduce total lumens even further. Everything else looks really good. G


----------



## wbp

Not sure - how old was the M60 that MrGman measured? Could be the newer one is brighter. Could be my readings are high. When I get time I'm going to pull the reference out of the Hoffman sphere and see what I get with that.

How does a crenelated bezel reduce lumens? Tat does not make sense to me. It might change the beam shape but the light is still going to find it's way out, so I don't see how it will affect the lumen reading taken with an integrating sphere.

Edit: Ah, as I ponder this, it occurs to me that the baffle needs to be opaque...

Edit2: The Creemator that I have is rated for just over 300 lumens, and that is what I measure. I just took them both outside to play, and the Malkoff is very close. So I'm thinking this M60 might actually be what I measured...


----------



## MrGman

My Malkoff that I measured is a brand new unit. The longer the black bezel is around the front of the reflector the more of the spill that it blocks. It absolutely makes a difference. I was losing at least 10 lumens from any pill that I measured in the Solarforce host compared to the 6P host. in the darkened room I could see that the total spill was wider on the 6P then on the Solarforce.

Yes the baffle should be opaque but frosty white. 

My PhD optical engineering friend said that a teflon sheet works even better than styrofoam for being a good full color spectrum reflector, with much better total reflectance. You could make a thin circular baffle out of aluminum plate and cover it in teflon tape and it would work.


----------



## wbp

MrGman said:


> My Malkoff that I measured is a brand new unit. The longer the black bezel is around the front of the reflector the more of the spill that it blocks. It absolutely makes a difference. I was losing at least 10 lumens from any pill that I measured in the Solarforce host compared to the 6P host. in the darkened room I could see that the total spill was wider on the 6P then on the Solarforce.



How does a wider or narrower spill affect the lumens? The photons still leave the light, just in a different pattern. Unless I'm missing something, that should not change the lumens measured. Unless the bezel is actually absorbing photons instead of reflecting them, which is certainly possible. That would be a better explanation.

The bezel on the Solarforce comes off, so it's easy enough to check. I already removed the glass since the Malkoff has its own.


----------



## precisionworks

> I already removed the glass since the Malkoff has its own.


I thought about doing that too. I'll check the lumens with & without the lens, probably 6-7 lumens difference on the M60.


----------



## wbp

OK, a quick post here, gotta run...

L2 w/ Malkoff M60, no lens, with bezel: 314 lumens
L2 w/ Malkoff M60, no lens, w/o bezel: 308 lumens
L2 w/ Malkoff M60, no lens, with bezel: 306 lumens
L2 w/ Malkoff M60, no lens, w/o bezel: 304 lumens

Nitecore Extreme SS Crenelated, on hi: 227 lumens

For reference:
Jetbeam II IBS on hi: 229 lumens

As I expected, bezel on/off makes no measurable difference. The integrating sphere is doing its job. Removing the L2's lens did though, picked up about 30 lumens (10%).

I'm off to the mountains for 6 days. Incommunicado in extrema.

William


----------



## LuxLuthor

precisionworks said:


> When the US Government eliminates incans, which is coming soon, there will be a major effort for warmer or color corrected LED lighting - there's not a woman in the world who wants put on makeup using an unflattering light source



Shame on you for even suggesting such an evil plan. You can be sure I will accrue a sufficient stockpile of incans to counteract any such events. :devil:


----------



## precisionworks

LMAO

The recently-passed 2008 energy bill has a section banning incandescent light bulbs for traditional (home & business) use. The phase-out will begin in 2012, with all incandescents gone by 2014. The bulbs will be replaced by LED and CFL bulbs.

My guess is that will accelerate the power LED market, which is just now starting to draw attention from makers of home lighting. That in turn should bring out better emitters for portable lighting.

I don't believe that flashlights are included in the government ban


----------



## wbp

I've been pondering the accuracy of our polystyrene spheres. I believe that lights that have a very small intense spot are not measured as accurately (or the same) as those with wider beams. I observe a "hot spot" on the outside of the sphere where the beam hits, and surmise that some light is getting through, and more so with more smaller beam spots.

It occurs to me that we might be able to improve this with the application of something directly opposite the input port. Perhaps a small disc of aluminum, for example, or aluminum coated by BaSo4. Seems like this would be something interesting to experiment with.

Also, if anyone is interested, I have been able to obtain service literature for the AEMC CA813 meters, and can now calibrate them. This meter claims to have "CIE Photopic" sensitivity, but like all such meters it is calibrated using an Illuminant A light source, which is a long way from our LED flashlights. Also, with any meter using a cosine receptor, the placement of the sensor is critical - this can introduce significant error during calibration. I've developed a new technique for calibrating this type of meter that yields significantly better results.

William


----------



## MrGman

Another option would be to use a slight diffusion filter of a known percentage drop of total light efficiency to spread out the light. I and precisionworks have been experimenting with just such a set of diffusers from Gene Malkoff, very nice material indeed. But if you knew the diffuser dropped the total light transmission by a solid 6%, then you could reevaluate all the tight spot beamed lights and see how they fair in that manner. I just got all my supplies back from Precisionworks (Thanks) I could send you a couple filter samples.


----------



## wbp

I have a pretty good collection of diffusion filters here already - which one(s) did you find helpful?

I found another problem with the polystyrene sphere - color shift. I had been recording CCT and coordinate readings taken with the sphere. A couple of days ago I needed to add color data for a particular light, so I set it on the stand and aimed it directly at the SP-100. Then I measured one of my reference lights the same way, and got *very* different numbers than what I get using the sphere. So all my CCT data done with the sphere gets tossed...

William


----------



## Ryanrpm

wbp said:


> Gentlepeople, I have installed a baffle, and the results are, I think, very interesting. First of all, a couple of pictures, showing the baffle and the sensor port:
> 
> http://www.meier-phelps.com/temp/IMG00025.jpg
> http://www.meier-phelps.com/temp/IMG00026.jpg
> 
> I admit, the baffle is a bit of a hack, not exactly round, but I was in a hurry. The black ring in the sensor port is a bit of rubber fuel line, it hold the tip of the fiber optic probe very nicely.
> 
> Now the measurements (cd/m2, CCT in K, calc'd Lumens):
> 
> 
> 
> Code:
> 
> 
> [FONT=Fixedsys]Fenix L0D Q5         Hi   2051  5455K    82
> Muyshondt Aeon       Hi   3219  5077k   129
> [/FONT][FONT=Fixedsys]Bitz Pocket          Hi   3252  6080K   130
> [/FONT][FONT=Fixedsys]Nitecore Defender    Hi   3387  6213K   135
> [/FONT][FONT=Fixedsys]Nitecore EX10        Hi   4220  5739K   169
> [/FONT][FONT=Fixedsys]Olight T10           Hi   4455  6147K   178
> [/FONT][FONT=Fixedsys]Dereelight DBS V2     -   5380  5633K   215
> [/FONT][FONT=Fixedsys]Jetbeam II IBS       Hi   5522  6048K   221
> [/FONT][FONT=Fixedsys]Lummi Raw NS         Hi   6688  6409K   258
> [/FONT][FONT=Fixedsys]Milkyspit Creemator  Hi   7674  6577K   307
> MTE SSC P7           Hi  11490  5674K   460
> [/FONT]
> 
> (The Fenix has freshly charged batteries)
> 
> I can repeat measurements and get within three percent. For example:
> 
> 
> 
> Code:
> 
> 
> [FONT=Fixedsys]Bitz Pocket          Hi   3332  -----   133    2.2%
> Muyshondt Aeon       Hi   3291  -----   132    2.2%
> [/FONT][FONT=Fixedsys]Olight T10           Hi   4580  -----   183    2.8%
> [/FONT][FONT=Fixedsys]Jetbeam II IBS       Hi   5675  -----   227    2.8%
> [/FONT]
> 
> Some of this error is due to the Lightspex recalculating dark frames every time it changes ranges. I'm being lazy and just covering the light being tested, and not actually pulling the probe and covering it...
> 
> These numbers look really good to me. I've got a Fenix T1 coming so I can check that.
> 
> At some point I want to do a run with a more affordable meter like one of the Extechs (I have a 403125 here) and see if I can calibrate that to get the same readings. If I can, then we could actually build these for a very reasonable price.
> 
> Other than that I think I'm done unless someone can point out something I'm missing. What fun!
> 
> William



Hi William, do you find that the Extech 403125 gives you pretty reliable lux readings?


----------



## wbp

Ryanrpm said:


> Hi William, do you find that the Extech 403125 gives you pretty reliable lux readings?



Depends on what you want to do.

I prefer the AEMC CA813. The Extech is not very linear. It is more difficult to calibrate than the CA813. Neither of them will give accurate lux readings for LED lights as received, regardless of factory calibration.

William


----------



## JWW

Hello,

I am new hear and read this thread a few months ago. Any chance of showing a few updated images of your integrating sphere in use?

Regards,
-JWW:


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## sygyzy

I want to build an IS or a lightbox this weekend. Can someone explain where the baffle needs to be placed and how large it has to be? I know you want to block direct light but size and shape, how far it drops down from the wall of the sphere and how much it wraps around the censor (180 degrees at flashlightreviews.com), are all important. It seems like the sizes an shapes of baffles being used here are just "random".


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## milkyspit

sygyzy said:


> I want to build an IS or a lightbox this weekend. Can someone explain where the baffle needs to be placed and how large it has to be? I know you want to block direct light but size and shape, how far it drops down from the wall of the sphere and how much it wraps around the censor (180 degrees at flashlightreviews.com), are all important. It seems like the sizes an shapes of baffles being used here are just "random".



Sygyzy, I don't have exact answers to your questions, but can vouch for both Quickbeam and Leef as having particularly well-designed lightboxes... don't recall if they posted detailed threads about their construction on CPF, but I'd try a search for their threads... either one ought to provide an excellent model for your own construction.

(To all: granted these aren't true integrating spheres, but for relative testing of one light to another where all the lights are LED, or all the lights are incandescent, my own past experience has been these boxes can do surprisingly well! And it puts fairly decent measurement capability within reach of most folks, from both cost and complexity standpoints.)


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## wbp

sygyzy said:


> I want to build an IS or a lightbox this weekend. Can someone explain where the baffle needs to be placed and how large it has to be? I know you want to block direct light but size and shape, how far it drops down from the wall of the sphere and how much it wraps around the censor (180 degrees at flashlightreviews.com), are all important. It seems like the sizes an shapes of baffles being used here are just "random".



The baffle needs to block the sensor such that no light from the source directly hits the sensor. Preferably it's made from the same material as the sphere, or coated with the same coating. It should only be big enough to cover the source opening from the perspective of the sensor opening.

Are you using a polystyrene ball? What size? What meter?

I've been "inspired" to try building a new sphere with a different type of ball. I've also been working on a way for anyone who does this to calibrate their sphere so we can all get accurate measurements. Stay tuned... 

William


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## sygyzy

I want the baffle to be near the source and not the sensor?

I am still confused about the shape, size and position of the baffle. Needless to say, I am baffled <--- get it?!?!

I was thinking about using the ball like in this thread but then I thought about the other lightboxes made in, well, boxes and they seem to work fine. Does it matter if the container is a sphere, house shape, pyramid, cube, or rectangle if the user is using it consistently across their lights?


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## wbp

The baffle goes between the sensor and the source. Typically they are half way in between. I posted some pictures of mine somewhere around here, can post again if need be.

If you want accurate results, it has to be a sphere. Otherwise you'll end up with different reflections for different beam shapes, and that will throw off the comparisons.

I am currently testing a 12" diameter (ID) sphere made from something a little different. Like I said, stay tuned...

William


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## wbp

has anyone thought about using one of these:

*http://www.walmart.com/catalog/product.do?product_id=7757565*

12 inch ID, white plastic. I've got one I'm playing with now. Drilled a 3" hole for the source, 7/8" for the meter. Using an AEMC CA813.

William


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## sygyzy

wbp - Well I built a rectangular light box. I think it'll be good enough to compare my lights against each other.

I'll build a sphere later. I saw your picture of the baffle but due to the way it was shot, it was a little confusing as to what I was looking at.

Let us know how that new sphere turns out.


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## run4jc

Wondering if this GREAT thread can be rejuvenated...I purchased a 16 inch smooth foam sphere and the same Extech Easyview 31 light meter that was mentioned in the beginning of this thread.

I have no illusions of being able to create an accurate IS - but what I would like to do is build something that gives consistent RELATIVE readings. After reading through all 4 pages of posts in this thread, it seems that the most important thing to ensure such (readings given the various shapes of beams) is to avoid any direct light hitting the sensor, accomplished by the installation of some type of baffle.

And it also appears that the installation of some type of tube to properly position the sensor is necessary, but how long is the right length? Just 'through' the styrofoam, or actually extending into the sphere for an inch - two inches - whatever? 

I've seen multiple photos of how baffles are positioned - debate over size and # of said baffles - any consensus on the best way?

Mine will be simple (read "cheap") and I will not glue the sphere - rather tape it like wpb's original so it can be modified/improved.

One more question - what makes us do this?  I spent $130 on a meter (cheap, I know), $40 getting a 16 inch smooth foam ball shipped to me - about to purchase a couple of lengths of PVC pipe and who knows what else - just to get MORE readings (so many are readily available)....and I can't WAIT to do it!! Heck, that money would have purchased a decent Surefire.

BTW, that was a rhetorical question - I know why we do it - we are FLASHAHOLICS!! :twothumbs:twothumbs

And again, I spent an hour reading this entire thread, so many of my questions are already answered, but if anyone has any new insight(s) since the last post almost a year ago, please weigh in!

Thanks!


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## jashhash

This is such an awesome idea and I'm so glad I found this post. After reading this post I have decided to undertake an Integrating sphere project too. I have already made a bobber cooler integrating sphere and it works great but im still not satisfied with the 4% error margin. I'm going to make a new sphere by plaster casting a 16 inch ball kind of like this one: 






Then I'm going to make a ultra reflective paint using 90% barium sulfate powder and 10% elmers glue. 

In case you might be interested you can get 500 grams Barium Sulfate powder from here: http://www.carolina.com/jump.do?keyword=barium+sulfate&Search.x=0&Search.y=0 for$13.50.


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## Mick

This paint system used for video projection screens might be good for the inside of the Styrofoam balls. The first coat is highly reflective and the top coat is a diffuser. I should block any light loss. 

http://www.goosystems.com/

This place will sell the GOO in 120 mL size which should be plenty for a IS.

http://www.rosebrand.com/shop/results.aspx?keywords=screen+goo

I have a wall painted with the stuff for my home theater.


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## precisionworks

Didn't realize how long I'd been away from this thread :nana:

I've added a few lights since I last posted ... will measure those today & update the chart.

Here's a copy of the chart from post #21, and including the Catapult V2 SST-50, plus the McGizmo Haiku 6 volt (High CRI emitter with custom set driver for lower lumen output/greater runtime).

First reading is my lumen calculation, followed by factory stated lumens:

Mac's Custom P7 (AW C-cell LiIon) = *782 lumens *(about 800 per Mac)

ThruNite Catapult V2 SST-50 (2xAW18650, 2900mAh) = *238/722 *(250/1000 emitter lumens)

Pocket Rocket - 8th run XM-L (T6-3B bin, 1xAW18650, 2900 mAh, ) =* 51/184/680 *

PR8 XM-L flux should be about 7% higher with the U2-1C bin, giving *55/197/728* Lumens (estimated)

Surefire 6PX-Pro LED = *16 / 235 lumens *(15/200 per SF)

Malkoff M60 with 60Ω Sandwiche Shoppe mod = *15/192 lumens* (235 per Malkoff website)

NiteCore Extreme XR-E Q5 = *5/186 lumens *(190 on Tactical High)

Early Surefire U2 = *7/114** lumens* (2/100 per SF) / Latest U2 *1/161 lumens*

_E2L two stage KX2 head = 12/119 lumens (1x17500) 

E2L two stage KX2 head = 11/118 lumens (2xCR123)

E2L two stage KX2 head = 11/113 lumens (1x18650) _ 

Surefire E1B = *11/113 lumens* (5/80 per SF)

Novatac 120P = *.23/11/99 lumens* (.23/10/120 per NovaTac)

Muyshondt Aeon = *10/92* *lumens* (?/114 per Muyshondt site)

Muyshondt Nautilus = *6/91* *lumens* (?/107 per Brightguy site) 

McGizmo Haiku 6v HCRI = *5/23/89* (5/25/90 per Don IIRC)

McGizmo LunaSol 20 = *9/73 lumens *(9/78 per Don)

Surefire L4 = *66 lumens* (100 per SF)

M60LL in Surefire G2 = *61 lumens* (80 per Malkoff site)

Surefire E2L (single stage Cree) = *57 lumens* (45 per SF)

McGizmo SunDrop = *46 lumens *(40-50 per Don)

Surefire E1L (single stage Cree) = *40 lumens *(30 per SF)

Muyshondt CR2 Ion = *3/29 lumens

*Surefire KL1 (Luxeon) head = *29 lumens

*Gerber Trio (2 AA Lithium) = *22 lumens *(24 per Gerber)

Does anyone reading this remember when ThruNite brought out the V2 Catapult (SST-50)? Quite a few people with calibrated spheres were reading about 700 OTF lumens, which caused David at ThruNite no end of distress. From everything I've read, emitter lumens X .66 = OTF lumens (more or less, plus or minus, approximately, etc.). If 66% is a valid number to use, the emitter lumens are closer to 1100. Whatever the case, it's my favorite thrower, possibly because it's my only thrower  Car drivers cannot move over quickly enough when the V2 is brought to bear.


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## HooNz

Is one lit Candle one Lumen in a sphere? and is the size of a candle uniform eg: a small birthday cake candle compared to a 6 inch candle , then petroleum based wax to bee's wax , a thick wick and the opposite , different wick compositions and all that stuff .

A quick answer would do me , unless one has the time or experience .


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## precisionworks

Finally received the Surefire 6PX-Pro that was ordered a few weeks ago from OMB Police Supply. They said it was on backorder, but it was worth the wait:thumbsup:

One of the nicest beam profiles that I've ever seen from a Surefire - not super tight like the TIR lights, not extra wide like the L4, but a well defined hotspot that fades nicely into the spillbeam. This light is a keeper, and $72.99 delivered is a price I can live with.

Surefire claims 15 lumens on low, my sphere showed 16 lumens, which is 6% higher than they state.

Surefire claims 200 lumens on high, my sphere showed 235 lumens, which is 15% higher than they state. 

Again, my sphere is not calibrated to ANSI standards, but rather shows relative brightness of the lights I've been able to test. 

The chart in post #117 has been updated with this addition.


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## precisionworks

Added NiteCore Extreme XR-E Q5. That's a little pocket rocket  NiteCore claims 190L, my reading is 186L, not bad for a single CR-123. Chart in post #117 updated.


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## precisionworks

Added the Pocket Rocket 8th run. The light tested has the T6-3B bin (best color temp, closest to noon daylight) & luminous flux on that bin is about 7% less than the "normal" U2-1C cool white.

51/184/680 Lumens with the T6-3B

55/197/728 Lumens estimated with the U2-1C


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## precisionworks

Update with output from the SWM V10R Ti. SWM state a low output of 1 lumen & 210 lumens on high. I measured half a dozen & all had a low level of 0.10 to 0.15 lumens & high at 184-187 lumens.


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