# Best Lux meters out there



## BVH (Jan 10, 2007)

I've been here long enough without having my own lux meter. I'm looking for info on purchasing a solid medium to very high quality lux meter. Brands, model numbers, what performance criteria/specs/numbers I should be looking for etc. All help is appreciated.


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## cmacclel (Jan 10, 2007)

BVH said:


> I've been here long enough without having my own lux meter. I'm looking for info on purchasing a solid medium to very high quality lux meter. Brands, model numbers, what performance criteria/specs/numbers I should be looking for etc. All help is appreciated.




The meterman 631 is the most popular on the board at around $100. A top of the line meter can sell for 5 times that. 

Mac


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## BVH (Jan 10, 2007)

Found an older thread that included a reference to an Extech 401036 with datalogging capabilities. In 30 minutes of Googling, it looks like this meter is accurate to within 3% whereas most others I saw are accurate to 5%. Still open to suggestions. I don't want to spend more than about $300 to $400.


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## cmacclel (Jan 10, 2007)

BVH said:


> Found an older thread that included a reference to an Extech 401036 with datalogging capabilities. In 30 minutes of Googling, it looks like this meter is accurate to within 3% whereas most others I saw are accurate to 5%. Still open to suggestions. I don't want to spend more than about $300 to $400.




3% to 5% would be NEGLIGABLE with a lux meter for measuring flashlights. If you have the hotspot focused on the sensor and move anything 0.00001 it will vary that much 

Mac


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## Bullzeyebill (Jan 10, 2007)

Cost is not the biggest factor if you are using the lightmeter to compare lux, or bounce, with other lights that you own. I am quite happy with my LM631 when checking for lux and bounce. It may not be 100% accurate compared to results derived from an integrated sphere from a professional lab, but it serves my purpose. When I read about lux measurements from other CPF folks I understand that my lightmeter may not give the same results, but I can picture a ball park figure for what I might obtain from the lights that they measured.

Bill


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## LuxLuthor (Jan 10, 2007)

$85 on this site I found with google.

How do you relate the lux readings to our discussions of bulb/torch lumens. When I read various explanations of Lux vs. Lumens, it seems really hard to make sense out of flashlight hotspots, which have significant variation in which part of the hotspot, and how far from the meter. It seems there are so many uncontrolled factors with a meter like this, it would be hard to know what various readings mean.

Some of these lights are so bright (Barn Burner, Mac's Torch, etc.) that you couldn't even see the reading if you put it right up close.


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## The_LED_Museum (Jan 10, 2007)

I've used the Meterman LM631 for quite a few years; it is the defacto standard light meter for CPF, and is reasonably accurate to boot.
It measures in FC (foot-candles) and LUX.


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## modamag (Jan 11, 2007)

BVH, what are you looking in a light meter? Pure lux reading, or you want the real thing lumens? If you can surfice w/o purchasing any lights for 3 months you can get yourself a 4" integrating sphere


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## BVH (Jan 12, 2007)

I understand that "Lumens" is a measurement of total light produced and emitted by a source in all directions as measured in an I.S. Lux, on the other hand, (Not you, Lux  ) is a measurement of luminosity at one point in space (or Earth, if you prefer).

Lux, (Yes, you, Lux  ) the way I would use Lux (No, not you, Lux  ) readings when talking about our superlights relates to throw. If Mtbkndad & I were at a range where there is little or no lighting influence from sources other than the lights we're shooting, then I could place the Lux (No, not you, Lux  ) meter say 500 or 700 yards away, aim the hot spot at the sensor, take a reading and then make an educated guess as to which light throws further (at least at the center of the hot spot) based on which one gives the highest Lux (No, not you, Lux  ) reading. At that distance, it may not make any difference to the human eye, but its fun to know the performance numbers. Makes sense to me, anyway. I would also use it to measure output of my small lights. Are you with me, Lux? (Yes, you, Lux  

Jonathan, I'd love an I.S. but I would want one that would fit the superlights and something that large would cost way more than what I would want to spend to get a lumens number. I'd rather spend money on more lights.


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## modamag (Jan 12, 2007)

Bob, it's the port size (where you point your light into). So some of you um hum... super large light will fit depending on the reflector size.


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## BVH (Jan 12, 2007)

Oh, didn't realize that. And it makes sense. If the whole light is in there, the light body would absorb some of the light and give a false reading. So i'd be looking for a port size of around 4+ inches for an Xeray. Still not sure if I want to go that way but any idea of the cost of such and brands to look at?


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## Josey (Jan 12, 2007)

I use the LM631 and find it pretty good. However, it is important to measure the 1 meter distance from the bulb, not the bezel. And I've found that I have to move the beam around to find the highest lux reading. Unless I do both of those things, comparisons between lights becomes much less accurate.


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## wasBlinded (Jan 12, 2007)

From the light meter benchmarking thread, it looks like the Extech meters are closer to the measured standard with white LEDs, and exhibit less meter to meter variation than the Meterman LM631. You had best look at the thread and decide for yourself.


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## LightingGeek (Feb 9, 2007)

The Gold standard in the lighting industry (lighting engineers, lighting designers) is the Minolta T10. It's going to cost about $1200. I've seen all the other meters tested by a photometric lab, and they can be off the mark anywhere on the scale. The $100 meters are usually trash, but if you can find one that is NIST calibrated, that's probably OK, as long as you get it calibrated every 12 months.
And LUX is a measurement of Incident Light (light that is about to hit a surface)


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## Ra (Feb 9, 2007)

Indeed any luxmeter that is not properly calibrated is quite useless.

And I must say that luxmeters with a prizetag below a certian figure mostly aren't calibrated!

I'm blessed with the oppertunity to calibrate my luxmeter at the calibration-facillity of the dutch navy.. And beleve me or not,, It was off by about 30%, the first time it was calibrated!!


Regards,

Ra.


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## LuxLuthor (Feb 9, 2007)

BVH said:


> I understand that "Lumens" is a measurement of total light produced and emitted by a source in all directions as measured in an I.S. Lux, on the other hand, (Not you, Lux  ) is a measurement of luminosity at one point in space (or Earth, if you prefer).
> 
> Lux, (Yes, you, Lux  ) the way I would use Lux (No, not you, Lux  ) readings when talking about our superlights relates to throw. If Mtbkndad & I were at a range where there is little or no lighting influence from sources other than the lights we're shooting, then I could place the Lux (No, not you, Lux  ) meter say 500 or 700 yards away, aim the hot spot at the sensor, take a reading and then make an educated guess as to which light throws further (at least at the center of the hot spot) based on which one gives the highest Lux (No, not you, Lux  ) reading. At that distance, it may not make any difference to the human eye, but its fun to know the performance numbers. Makes sense to me, anyway. I would also use it to measure output of my small lights. Are you with me, Lux? (Yes, you, Lux
> 
> Jonathan, I'd love an I.S. but I would want one that would fit the superlights and something that large would cost way more than what I would want to spend to get a lumens number. I'd rather spend money on more lights.



It was a tricky read, but I actually followed you. It is amazing how much fluctuation there is even with these cheaper uncalibrated Meterman 631 models (as Ra pointed out) when trying to find the hottest spot in the hotspot...but it is still useful to use these to get some objective comparison for the many lights I now have.


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## KillingTime (Feb 11, 2007)

The LM631 can be out by 20% or more. My earlier thread:

https://www.candlepowerforums.com/threads/132290

It depends on what you are comparing your readings to; other meters, lights of different colour temperatures etc..

Having the LM 631 is better than nothing, and as for the reading variations, better the devil you know. It could well be that meters in the same price range have a quality control that's just as bad, but with the 631, at least we've all compared them to gauge what the likely variations are.

I take a reading from mine then push it through a formula to get what the reading should be.

It doesn't even help if you get the meter calibrated, because for run of the mill cals, all they do is calibrate it against a single light source (& colour temp). If you want to know how far your meter is off full spectrum, then you have to find a standards house that's got all the different light sources - very expensive (think many times what you paid for the 631).


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## Frenchyled (Feb 11, 2007)

Personally I use a Beha Luxmeter with datalogging capabilities..and I am quite happy with it 

It seems it is the same as Extech 401036.

I know lot of CPFer have LM631..and about the calibration I found lot of thread where measurements are not the same as mine...but not on the same flashlight too 
To really compare two luxmeter, we need the same conditions of measurement..exactly the same flashlight, distance, batteries, room and exterior light conditions !!


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## BVH (May 5, 2008)

It's been a few months. Any new hot light meters out there. Never bought one and would still like to. How does one calibrate a meter once one has one?


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## BVH (May 6, 2008)

OK, where's the rangefinder folks who should be here also? Can't have a rangefinder without a lux meter, right?


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## BVH (May 8, 2008)

Without search working, it might be difficult to see this thread. A little bump.


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