# Zebralight H51w is too dim. Is the H51 cool white better for trail running?



## Outdoorsman5 (Jun 20, 2011)

I'm somewhat new to neutral tinted lights. I bought a Zebralight H51w (neutral white) a couple of months ago for running, and the tint seems to make this light appear dark for the amount of lumens it produces. Both the spot & especially the spill seem darker than my cool white lights with similar lumens, and I'm running it on a fresh eneloop each time. Is this a common impression by many others? It is dissapointing as I like the way the tint looks & the color rendering, but for running it seems too dim. I'm now considering getting the H51 cool white version to see if I can see better with it. I had one briefly last year, but gave it away as a gift, so I can't compare....dang.

I go running before sun up. Half of my run is around a lake out in the open, and I only need 25-50 lumens. The other half is on trails in the woods where I need a lot more lumens with a good balance of flood & throw. I got tired of running with the H51w, so two weeks ago I switched back to my Zebralight SC60 cool white on a Nitecore headband (light sits on top of my head.) On the 140 lumens setting the sc60 seems brighter than the H51w on max (rated at 172 lumens.) The H51w is more comfortable to wear though, which is why I want to stick with this type of headlamp (small, lightweight, & rides on forehead.) I use a Nite Ize headband with the H51w which is very comfortable & keeps the light from bouncing. 

So again, does anyone else have the impression that neutral white lights seem dim compared to cool white lights that have the same amount of lumens & a similar beam profile?


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## GeoBruin (Jun 20, 2011)

I think there's a *lot* of different things going on here. I will try to address each of them in turn. 

First of all, it has been my experience that you are doing yourself a great disservice by trying to use a head lamp not in total darkness. I don't know if you are, but you said you go running before sun up so I assume it gets light at some point during your run. I have always found that a little bit of daylight (even a VERY little bit) makes my lights appear to perform very differently. I prefer to run in either total darkness where my lights perform very well, or in enough daylight that I don't need a light. When I do get caught doing an adventure race that spans day and night, I always find dawn and twilight the hardest times to regulate my light situation. I'm just throwing this out there because it's something I've noticed although I really don't have an explanation (or a solution).

Second: You're not comparing apples to apples. You asked about lights that have the "same amount of lumens & a similar beam profile" but they do not have the same beam profile. The H51w and the SC60 have the same emitter but the SC60 has a larger reflector. This will always result in a tighter beam, and the perception of increased brightness. I'm not saying this is the whole reason for what you are experiencing (as you will see below) but I believe it could be part of it. 

Now, if we do compare apples to apples (I have both the H51 and H51w) The H51 does seem noticeably brighter, even when on comparable levels. But again, I believe there are some faulty perceptions that may cause us to _think_ that the H51 is better at lighting up the trail. Let me explain:

When you're running on a trail, you're looking primarily at objects that are various shades of browns and greens. When you shine a cool light in front of you, the contrast between the areas that are illuminated by your light and those that are not is greater than the contrast would be with a warmer tinted light. This creates the perception that the light is brighter. In fact, you don't actually want a bunch of cool light reflected back to your eye. You want the color of whatever the object is that you are illuminating to be reflected back to your eye. The problem is that when this happens, you don't notice as dramatic an increase in contrast between light and dark as you do with a cool light so your brain thinks that you're not seeing as much light. You see, you brain knows what color it expects things to be, so when it sees them appear in those colors, there's nothing surprising. But when something appears with a bluish tint caused by a cool light reflecting off of it, your brain immediately recognizes that something is different from normal and that difference registers a larger magnitude. Sorry if this is a poor explanation but it's the best I can do. 

Now I'll talk about something else I've noticed regarding the H 5x series lights and trail running. The beam pattern of the H51/H51w is actually a little too tight for trail running. The problem is that I naturally adjust the hot spot such that it is right in the middle of my vision, where I'm looking most of the time. I imagine this is what most people do. What I noticed though is that because I'm staring right at the hot spot, my pupils tend to contract because there is a ton of light bouncing back in from one place, similar to looking at the Sun. When you pupils are contracted like this, your eyes tend to shut out what is being illuminated by the spill in your periphery. It's kind of like when people use video cameras to do beam shots of lights. When they first turn the light on, the sensor reacts by limiting the amount of light it lets in because the hot spot is so bright so all you see on your screen is a round circle of light in the middle when you know very well that there are several lumens of spill. To test this theory, I put some commonly used diffuser film (dc-fix) on my headlamps. I expected that the perceived brightness of the hot spot to drop because the hot spot was diffused but what I discovered was actually the opposite. Because there was no super bright hot spot, my eyes did not try to adjust as much, and everything appeared brighter. There was no noticeable loss of brightness in the center of my vision but everything in my periphery became brighter. I could now see the entire width of the trail illuminated evenly and my eye was more aware of what was happening at my feet, out in front of the hot spot, and on either side of the trail. I did one light first and took both out on the trail. I ran with both for part of the run but I quickly became annoyed with the un-modified light because I felt like I had tunnel vision. I ended up completing the run with the diffused light on my head and the other in my pocket. When I got home, the first thing I did was cut out another piece of dc-fix and stick it on my other Zebra. 

The long and short of it is, there are probably several things contributing to the perception that the cool light is better at lighting up the trail. I think if you look critically however, you can see why some of those might be misconceptions. Also, try some diffuser film. I know you're hesitant to lose some throw, but in practice it makes the whole experience more enjoyable.


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## gcbryan (Jun 20, 2011)

I agree with the above post regarding diffusing a headlamp beam as generally improving things as long as it throws as far as you need it to. Throwing a diffused beam rather than a spot beam (interesting use of the word throw I know) works better IMO. It's only if it's diffused so much that it doesn't light up the area ahead of you enough that it's a problem.

I've somewhat diffused the spot beam on my headlamp but I also have a pure flood mode and there is a big difference between the two. I wouldn't/couldn't be running very fast using the pure flood mode but the diffused spot mode would be great.

Regarding the neutral/warm thing. I think it's trying a little too hard to like neutral/warm if you have to argue with your brain  First of all most lights that offer cold/neutral/warm do put out less lumens when you choose neutral or warm. The other (probably greater) issue is the lack of contrast. That's why I don't get the neutral/warm thing for the most part.

I relax in my house with incan as does everyone else but I work under cold white lights and when I'm outside I'm in the bright, white sunlight for most of the things I do. I'm not generally as active in the warm light at sunset even though it's pretty to look at.

I think the solution is just what you've figured out...go back to the cold white light that you prefer.


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## Outdoorsman5 (Jun 20, 2011)

WOW GeoBruin, I needed to hear from someone with experience, and you delivered. What you have said makes perfect sense. I already knew about tunnel vision, and am getting tunnel vision quite a bit with this light (more so than with the sc60 though.) But, what I didn't understand or consider is that because the colors are rendered better with the neutral tint things seem darker - the browns are brown, the greens are green, etc...which must be making things look darker. When I use my sc60 or even my sc31 on my head things are lighter in color or "washed out." This must be why I'm perceiving those lights to be brighter since more light is bouncing off of surfaces that normally shouldn't bounce much light off of. 

It's very dark when I hit the road (4:30 CDT,) and I'm usually done by 5:30. The sky lights up a little during my run, and by the time I'm out of the woods I no longer need a light. So, ambient light does contribute to my problem towards the end of my run, and I agree with you that some dc-fix film could solve the problem. Where did you get it? Also, thanks for the help.


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## Outdoorsman5 (Jun 20, 2011)

gcbryan said:


> I think the solution is just what you've figured out...go back to the cold white light that you prefer.



I think you may be right. I have been trying a little too hard to like neutral tint. I have to admit though I love my ZL H501w (great for close up work & reading, and very easy on the eyes,) but for outside things like running in the dark I'm finding myself back-peddling towards cool white again.


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## gcbryan (Jun 20, 2011)

I think one of the problems that people sometimes have with cool bright and the washed out look is just that they have the light on too bright a setting.

My headlamp has infinitely brightness adjustment (ramping style) so I put it on low and then raise the brightness level to just the right level for present circumstances. Things don't look so washed out if you do that. Not a colorful as they would with a warm emitter but that's because the emitter is coloring them


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## GeoBruin (Jun 20, 2011)

Outdoorsman5 said:


> WOW GeoBruin, I needed to hear from someone with experience, and you delivered. What you have said makes perfect sense. I already knew about tunnel vision, and am getting tunnel vision quite a bit with this light (more so than with the sc60 though.) But, what I didn't understand or consider is that because the colors are rendered better with the neutral tint things seem darker - the browns are brown, the greens are green, etc...which must be making things look darker. When I use my sc60 or even my sc31 on my head things are lighter in color or "washed out." This must be why I'm perceiving those lights to be brighter since more light is bouncing off of surfaces that normally shouldn't bounce much light off of.
> 
> It's very dark when I hit the road (4:30 CDT,) and I'm usually done by 5:30. The sky lights up a little during my run, and by the time I'm out of the woods I no longer need a light. So, ambient light does contribute to my problem towards the end of my run, and I agree with you that some dc-fix film could solve the problem. Where did you get it? Also, thanks for the help.


 
I believe I got the sample I have from shao.fu.tzer in the CPF MarketPlace.


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## nzbazza (Jun 20, 2011)

Consider the ZL H51Fw or as noted above use some frosted film on the glass to diffuse the spot somewhat. The diffused lights up the surrounding area better than the side spill from the H51w and so appear brighter.


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## Bolster (Jun 20, 2011)

GeoBruin said:


> Because there was no super bright hot spot, my eyes did not try to adjust as much, and everything appeared brighter. There was no noticeable loss of brightness in the center of my vision but everything in my periphery became brighter. I could now see the entire width of the trail illuminated evenly and my eye was more aware of what was happening at my feet, out in front of the hot spot, and on either side of the trail. I did one light first and took both out on the trail. I ran with both for part of the run but I quickly became annoyed with the un-modified light because I felt like I had tunnel vision. I ended up completing the run with the diffused light on my head and the other in my pocket. When I got home, the first thing I did was cut out another piece of dc-fix and stick it on my other Zebra.



I can totally relate. For some reason I'm sensitive to this effect...I swear I can feel my iris cranking open and cranking shut...if I need to move my eyes around with the traditional spot-spill beam, my eyes feel tired quickly. Thus my addiction to "featureless" wide-beam flood lights.


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## Gregozedobe (Jun 21, 2011)

If you are prepared and able to spend the $$$ a custom "spike" headlamp from ahorton here on CPFM will have a lot of extra "oomph" in flood beam mode (2 x XP-Gs with flood optics) to cover the transition from dark to dawn. But it is bigger and heavier as well as more expensive


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## Outdoorsman5 (Jun 21, 2011)

I have a new ZL H51 cool white on the way. Ordered it yesterday. 
I went running this morning again, but this time I put both the ZL SC60 (cool white) and the H51w on the same nitecore headband (prolly looked a little goofy, but no one saw me,) and again the SC60 on the 140 lumen setting looked A LOT brighter than the SC51w on max (172 lumens.) The beam on the SC51w just seemed to be too brown in color to be very bright. To me both reflectors on these two lights look to be identical in size & shape with practically the same beam profile (spot vs. flood.) I guess I'm learning the hard way ($$) that I like cool white better for running.

Thanks again geobruin for the info regarding the dc-fix film. I'll try it out.


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## gcbryan (Jun 21, 2011)

Scotch "Magic" Tape also works and is more available.


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## GeoBruin (Jun 21, 2011)

Another alternative I didn't mention that I have been considering myself is the Spark ST6-460NW. It's got an XML and puts out 300 lumens on high (460 on "boost" for 5 minutes) and it comes with a frosted diffuser lens. It runs on an 18650 so it's obviously heavier than the ZL but it has a built in top strap that might prevent it from bouncing. 

I guess its that or just wait for the H502w from Zebralight.


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## Outdoorsman5 (Jun 22, 2011)

GeoBruin said:


> Another alternative I didn't mention that I have been considering myself is the Spark ST6-460NW.
> 
> I guess its that or just wait for the H502w from Zebralight.



I've considered the Spark too, but seems like I read somewhere that because of the design it would not be good for running. I think the head bounces too much which also creates a problem with keeping it aimed. Seems like I read that the light, when bounced around, will aim up then down & on & on. I don't know where I read that though.

I'm extremely excited about the new ZL H502 as I love my H502w. Hope it's bright enough to go trail running.


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## tedh (Jun 22, 2011)

I tried my H501w for trail running, and it didn't work so well. I found that because of the wide flood, areas just in front of me were well lit, but areas further out (>3m/10ft) were much more dimly lit. I just wasn't getting the information I needed on what obstacles were coming up. 

I thought about putting the 501 on a belt, and carrying another light, but I never got around to it. 

Ted


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## Outdoorsman5 (Jun 22, 2011)

Yeah, the H501w doesn't work for trail running at all...too dim & too floody. It is, however, the best light ever for close up work & reading. I am hoping that the new H502 with the XML LED in it will be bright enough to take trail running. I'm doubtful simply because it will be pure flood like the H501, but maybe it'll be bright enough.


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## tedh (Jun 23, 2011)

I see your point that maybe more brightness will make a difference...based on my experience, you could have 1,000 lumens out the front and it still wouldn't work. The bright light close in adapted my eyes to that brightness, so looking further out everything was too dark. Put another way, the lamp just isn't putting the light where you need it. Completely agree with you it's a great light for close up work, but for peering down a trail, I couldn't make it work, for the reasons you mentioned. I'd be curious if somehow the increased output of the 502 will make it happen. 

Ted


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## gcbryan (Jun 23, 2011)

Making the output greater would only help by extending the illuminated area marginally. If it almost works now maybe it will work with the new light. If it throws no where near enough then the new light isn't going to work.


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## tedh (Jun 23, 2011)

Yeah...I just worry that the additional output, if it's in the same beam shape, is just going to make my pupils restrict even more. It would be ironic if more lumens made the situation worse!

Ted


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## gcbryan (Jun 23, 2011)

It generally does at night. I have a headlamp with infinite brightness adjustment (ramping) which I like but the one thing that annoys me is that it always starts on high.

So at night even though I'll generally set it closer to the lowest setting I always have to look at the glare from high first!


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## Outdoorsman5 (Jun 29, 2011)

Update -- I received the Zebralight H51 cool white version Friday, and have taken it running with me every morning. Comparing it to my ZL H51w neutal white version, the cool white version is noticeably brighter. It's not a big difference indoors, but there seems to be a bigger difference outdoors (for reasons discussed above with GeoBruin.) The neutral white H51w is much nicer looking indoors, but the cool white H51 is much better (IMO) & more useful outdoors for trail running & seems brighter in every way (spot & especially spill.) 

I now clearly see that for indoors I prefer neutral white, but for outdoors I prefer cool white for the perceived brightness. Even in my backyard this morning the neutral white light just seems dull compared to the cool white when lighting things up. I don't think I'll be buying very many more neutral white lights after this experience since I use my lights outside more often.

I know there are a lot of die-hard neutral fans out there, and I understand it. I now recognize that throughout my day I'm mostly using pure white or cool white lights to light up my office and my home. It's only at night while relaxing & watching TV that I prefer my neutral white lamps to be on. My lamps are similar in color to the neutral white color of the H51w. They are dimmer lights, and perfect for when I use them. Looks like I'm a bigger fan of cool white lights for most things though, but it's nice to have both.


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## carbonita (Jul 22, 2012)

By any chance, have you had a chance to compare H51 with H502 for running? I'm choosing between the two at this point, but attracted by the potential versatility of dc-fix on h51 when needed. 



Outdoorsman5 said:


> Update -- I received the Zebralight H51 cool white version Friday, and have taken it running with me every morning. Comparing it to my ZL H51w neutal white version, the cool white version is noticeably brighter. It's not a big difference indoors, but there seems to be a bigger difference outdoors (for reasons discussed above with GeoBruin.) The neutral white H51w is much nicer looking indoors, but the cool white H51 is much better (IMO) & more useful outdoors for trail running & seems brighter in every way (spot & especially spill.)
> 
> I now clearly see that for indoors I prefer neutral white, but for outdoors I prefer cool white for the perceived brightness. Even in my backyard this morning the neutral white light just seems dull compared to the cool white when lighting things up. I don't think I'll be buying very many more neutral white lights after this experience since I use my lights outside more often.
> 
> I know there are a lot of die-hard neutral fans out there, and I understand it. I now recognize that throughout my day I'm mostly using pure white or cool white lights to light up my office and my home. It's only at night while relaxing & watching TV that I prefer my neutral white lamps to be on. My lamps are similar in color to the neutral white color of the H51w. They are dimmer lights, and perfect for when I use them. Looks like I'm a bigger fan of cool white lights for most things though, but it's nice to have both.


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## Outdoorsman5 (Jul 23, 2012)

carbonita said:


> By any chance, have you had a chance to compare H51 with H502 for running? I'm choosing between the two at this point, but attracted by the potential versatility of dc-fix on h51 when needed.



Not yet. I'm waiting on the H502w, and am not planning on using it as a running light. I'm sure I will try it out on the trail though. I prefer a headlight with some throw when in the woods running on trails. My favorite is my H600 for its run times and output. My favorite AA trail running light is still the H51. It works ok with diffuser material on it, but I prefer it more without it. On running trails I need more throw so I can see far enough ahead. In the summer I need the throw more for spotting spider webs (a face-full of spider webs sucks.) 

I have an H501w (pure flood,) and feel that it is not bright enough & doesn't throw well enough for trail running. It works good on the streets though, but still needs to be brighter. The H501w is, however, my favorite general use headlight...I love pure flood. I use it more than any other headlight for around the campsite & around the house, and am looking forward to the upgraded H502w (when it comes out.)


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## Woods Walker (Jul 28, 2012)

Outdoorsman5 said:


> Update -- I received the Zebralight H51 cool white version Friday, and have taken it running with me every morning. Comparing it to my ZL H51w neutal white version, the cool white version is noticeably brighter. It's not a big difference indoors, but there seems to be a bigger difference outdoors (for reasons discussed above with GeoBruin.) The neutral white H51w is much nicer looking indoors, but the cool white H51 is much better (IMO) & more useful outdoors for trail running & seems brighter in every way (spot & especially spill.)
> 
> I now clearly see that for indoors I prefer neutral white, but for outdoors I prefer cool white for the perceived brightness. Even in my backyard this morning the neutral white light just seems dull compared to the cool white when lighting things up. I don't think I'll be buying very many more neutral white lights after this experience since I use my lights outside more often.
> 
> I know there are a lot of die-hard neutral fans out there, and I understand it. I now recognize that throughout my day I'm mostly using pure white or cool white lights to light up my office and my home. It's only at night while relaxing & watching TV that I prefer my neutral white lamps to be on. My lamps are similar in color to the neutral white color of the H51w. They are dimmer lights, and perfect for when I use them. Looks like I'm a bigger fan of cool white lights for most things though, but it's nice to have both.


I am surprised you can distinguish given the relatively low % of lumens between them. For me it has got to be a good % higher before in actual use I could tell. Maybe it is a the tint that makes one light look noticeably brighter than the actual lumens? Heck if I know.


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## beamis (Jul 29, 2012)

Woods Walker said:


> I am surprised you can distinguish given the relatively low % of lumens between them. For me it has got to be a good % higher before in actual use I could tell. Maybe it is a the tint that makes one light look noticeably brighter than the actual lumens? Heck if I know.



I have an H51w and a Quark AA2 S2, which are supposed to be nearly equal in lumen output. The Quark is noticeably brighter than the H51W in all respects. I sincerely doubt I can see a 5 lumen difference that well. Just guessing, it seems more like about 50 lumens or so brighter.


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## tickled (Jul 29, 2012)

GeoBruin said:


> I think there's a *lot* of different things going on here. I will try to address each of them in turn. First of all, it has been my experience that you are doing yourself a great disservice by trying to use a head lamp not in total darkness. I don't know if you are, but you said you go running before sun up so I assume it gets light at some point during your run. I have always found that a little bit of daylight (even a VERY little bit) makes my lights appear to perform very differently. I prefer to run in either total darkness where my lights perform very well, or in enough daylight that I don't need a light. When I do get caught doing an adventure race that spans day and night, I always find dawn and twilight the hardest times to regulate my light situation. I'm just throwing this out there because it's something I've noticed although I really don't have an explanation (or a solution).


 I am not sure what you're saying the OP should be doing? Plan living activities around the lights that he owns or simply get something that fits better? My neutral light has always seemed dimmer in appearance compared to cool lights at equivalent lumen levels. No idea as to why but it just is.


> When you're running on a trail, you're looking primarily at objects that are various shades of browns and greens. When you shine a cool light in front of you, the contrast between the areas that are illuminated by your light and those that are not is greater than the contrast would be with a warmer tinted light. This creates the perception that the light is brighter. *In fact, you don't actually want a bunch of cool light reflected back to your eye. You want the color of whatever the object is that you are illuminating to be reflected back to your eye.*


 That may be what you want...


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## reppans (Jul 30, 2012)

beamis said:


> I have an H51w and a Quark AA2 S2, which are supposed to be nearly equal in lumen output. The Quark is noticeably brighter than the H51W in all respects. I sincerely doubt I can see a 5 lumen difference that well. Just guessing, it seems more like about 50 lumens or so brighter.



I think your eye meter is a bit off - I think the difference is going to be more like 75 lumens. 

I have a QAA2X in NW that I use with a 1xAA tube, it is rated at 107 lm on high (max is the same) and I've just tested it's high against my H51w's 172 lm max using my DSLR light meter (both lights ceiling bounced in a small bathroom, light metered off a piece of paper on the floor). The Quark is a hair brighter, both are on an Eneloop. I also have the QAA2 S2, and with 2 batts, there's no point in testing it - it's a slaughter. You're probably looking at 105 vs 180.

Someone is fibbing big time here.... I always heard FourSevens is conservative with its specs, but sheesh, can it explain that much of a difference?:thinking:


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## bbb74 (Jul 30, 2012)

reppans said:


> Someone is fibbing big time here....:thinking:



I kind of suspect so.

There is a noticeable difference between my SC51 or H51 vs my SC51w. There is also a big difference between my Quark AA2 R4 neutral and the sc51w, guessing I'd say about 50 lumens. It wouldn't surprise me if my sc51w was in the low-ish 100's. This is when using eneloops.


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## srfreddy (Jul 30, 2012)

bbb74 said:


> I kind of suspect so.
> 
> There is a noticeable difference between my SC51 or H51 vs my SC51w. There is also a big difference between my Quark AA2 R4 neutral and the sc51w, guessing I'd say about 50 lumens. It wouldn't surprise me if my sc51w was in the low-ish 100's. This is when using eneloops.


I'd look at selfbuilt's reviews a bit harder if you're saying that... the SC51 is 200 lumens, beamshots show the cool and neutral variants to be roughly comparable. R4 neutral bins are common for the XPG, R5 is common for cool. I doubt that the difference between R5 and R4 is 100%.


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## bbb74 (Jul 30, 2012)

srfreddy said:


> I'd look at selfbuilt's reviews a bit harder if you're saying that... the SC51 is 200 lumens, beamshots show the cool and neutral variants to be roughly comparable. R4 neutral bins are common for the XPG, R5 is common for cool. I doubt that the difference between R5 and R4 is 100%.



All I can say is with the same batteries, using ceiling bounce there is a noticeable difference between SC51 and SC51w. It would have to be much more than 7% otherwise I doubt I'd notice it (and note even zebralight don't claim the difference is 7% - the drop from "200" lumens to "172" is more than 7%). And I can see a much bigger ceiling bounce difference between SC51w and Quark AA2 neutral. Of course that is comparing 1xAA to 2xAA, but a claim is a claim. It could just be my light but I've seen a few people now who have doubted the output on their sc51w's.


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## reppans (Jul 30, 2012)

bbb74, what's your QAA2 NW rated for, and how does it compare to the SC51? You think this lumen overstatement is unique to the 51w's? 

I don't have any other ZLs.


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## Mr Floppy (Jul 31, 2012)

Have you guys perhaps have a dud?

Here's a review of the SC51w from a year back. 
http://www.candlepowerforums.com/vb...he-Zebralight-SC51w-(replete-with-beamshots!)


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## bbb74 (Jul 31, 2012)

reppans said:


> bbb74, what's your QAA2 NW rated for, and how does it compare to the SC51? You think this lumen overstatement is unique to the 51w's?
> 
> I don't have any other ZLs.



4sevens didn't provide official rating for it, but it was described as being 7% less than the cool version (206 lumens).

I haven't compared the sc51 to the qaa2, I'll give that a go.


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## beamis (Aug 2, 2012)

Here's my H51w compared to a Quark AA2 S2


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## beamis (Aug 2, 2012)

So I got to the office and decided to use some of our equipment to measure the output of the lights. I used an Extech EasyView 33 light meter and because this sensor measures lux I held each light on high right up to the sensor to get the maximum value. The results are that the Quark AA2 S2 registers 634,100 lux and the Zebralight registers 431,400 lux. My eyes do not deceive me.











If that sensor is 3/4" in diameter and we assume all of the light is falling on the sensor (or close enough), that puts the Quark AA2 S2 at 181 lumens and the Zebralight at 123 lumens. That jives with what my eyes see, but it makes me a little bit angry that this light is represented as 170+ lumens when it clearly is NOT.


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## reppans (Aug 2, 2012)

I'm also quite disappointed.... maybe we do have duds as has been mentioned above, but that makes 3 of us which is pretty bad. 

I still like my ZL for its low modes and hands-free versatility, and that's what I bought it for... those levels look about right to me. But for this type of overstatement, short warranty, and what sounds to be relatively poor customer service, I find myself buying many more 4/7s products when I want an efficient, long runtime light.


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## Mr Floppy (Aug 2, 2012)

beamis said:


> So I got to the office and decided to use some of our equipment to measure the output of the lights. I used an Extech EasyView 33 light meter and because this sensor measures lux I held each light on high right up to the sensor to get the maximum value.



I'm not sure that is the best way to measure it. Can you build a small integrating sphere of some sort? A shoe box painted white perhaps?


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## beamis (Aug 2, 2012)

Mr Floppy said:


> I'm not sure that is the best way to measure it. Can you build a small integrating sphere of some sort? A shoe box painted white perhaps?



The sensor is larger than the head of both lights. Essentially all of the light is going into that sensor (minus some trivial amount reflected away, but the sensor should be calibrated for that). Even if the lumen calculation is off, the relative difference is undeniable. The Quark is definitely 47% brighter than the Zebralight.

Another thing to note is that the value for the Zebralight never stabilized, it just kept dropping and dropping. I just snapped the picture after about 30 - 45 seconds (and it had dropped about 15,000 lux in that time). If I would've waited for the full ANSI specified time of three minutes I'm sure it would have been even dimmer.


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## srfreddy (Aug 2, 2012)

Mr Floppy said:


> I'm not sure that is the best way to measure it. Can you build a small integrating sphere of some sort? A shoe box painted white perhaps?


I also am a bit doubtful of that method of measurement. You could try ceiling bounce in a dark room with a white ceiling... also, neutral lights have a different wavelength pattern than cool lights, and light meters can be calibrated to different patterns, affecting measurements between neutral and cool white lights.


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## srfreddy (Aug 2, 2012)

beamis said:


> The sensor is larger than the head of both lights. Essentially all of the light is going into that sensor (minus some trivial amount reflected away, but the sensor should be calibrated for that). Even if the lumen calculation is off, the relative difference is undeniable. The Quark is definitely 47% brighter than the Zebralight.
> 
> Another thing to note is that the value for the Zebralight never stabilized, it just kept dropping and dropping. I just snapped the picture after about 30 - 45 seconds (and it had dropped about 15,000 lux in that time). If I would've waited for the full ANSI specified time of three minutes, I'm sure it would have been even dimmer.


You need the light to be evenly distributed across the sensor, hence the need for an integrating sphere. You also need to take the square root of lux measurements to find relative lumen measurements- There is only an 18% difference in the lumen values you found, if they were accurate.


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## beamis (Aug 2, 2012)

I realize that this isn't a test that can be used to authoritatively measure the output of all lights, but since both lights in this case have very similar beam patterns and reflector sizes the relative difference between them is still valid. The data from these readings correlates not only with my initial assessment of the relative brightness between the lights, but also with 4Seven's lumen ratings. It would be a pretty amazing coincidence to have a Zebralight look dimmer than a Quark by about 50 lumens, read dimmer on the lux meter by just what you'd expect for a light about 60 lumens dimmer than the Quark, have the Quark read at values that one would expect for the rating claimed by 4Sevens, and actually have it turn out that all of those observations and measurements were wrong. I'm not saying it's not possible, but it's going to take a lot more than second-guessing to knock cold, hard data in my mind. I'm going to see if I can borrow the meter to do a ceiling bounce test or some other form of test on reflected light. I'll have to do it fast though because I've got an RMA on the Zebralight.

123 lumens is only 70% as bright as 181 lumens.


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## srfreddy (Aug 4, 2012)

The quark AA^2 isn't 181 lumens though.


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## reppans (Aug 4, 2012)

He said earlier he had an XPG S2


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## moldyoldy (Aug 4, 2012)

beamis said:


> The sensor is larger than the head of both lights. Essentially all of the light is going into that sensor (minus some trivial amount reflected away, but the sensor should be calibrated for that). Even if the lumen calculation is off, the relative difference is undeniable. The Quark is definitely 47% brighter than the Zebralight.
> 
> Another thing to note is that the value for the Zebralight never stabilized, it just kept dropping and dropping. I just snapped the picture after about 30 - 45 seconds (and it had dropped about 15,000 lux in that time). If I would've waited for the full ANSI specified time of three minutes I'm sure it would have been even dimmer.



If your perceptions are correct, your NiMH cell was not able to source the continued high current draw of the Zebralight w/o an excessive voltage drop. I have measured the current draw on several of my Zebralights (SC51, H51, etc.) and I routinely observe levels of 2.5+ amps. That is rather a lot for an AA cell. There are not many NiMH cells that can souce 2.5A-3A without excessive voltage sag.

As a quick check, when the light is on high, double click from H1 to H2. If the difference is not obvious, the AA cell is not supplying the necessary current.

In any case, before such tests, the cells need to be fully charged to cutoff. Comparisons are especially troublesome with cells of varying discharge levels. I find remarkable differences between ostensibly similar output lights - all due to cells discharged beyond some 10-20% of capacity, meaning a run time on high of maybe 10 minutes from coming off a charger.


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## moldyoldy (Aug 4, 2012)

and in answer to a possible question, I have an SC51 from before the driver update and one from after the driver update. There still needs to be an easily observable output change between H1 and H2. Otherwise the AA cell is not supplying sufficient current at 2.5+ amps. The H1 & H2 difference with a fully charged battery with the new driver is admittedly greater.


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## srfreddy (Aug 4, 2012)

reppans said:


> He said earlier he had an XPG S2


The R5 AA^2 is rated at 205 lumens, the S2 would be about... 220.


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## reppans (Aug 4, 2012)

moldyoldy said:


> ...There still needs to be an easily observable output change between H1 and H2. Otherwise the AA cell is not supplying sufficient current at 2.5+ amps. The H1 & H2 difference with a fully charged battery with the new driver is admittedly greater.



I can see an obvious diff between the H1 and H2 on my H 51w still no comparison to a Quark S2



srfreddy said:


> The R5 AA^2 is rated at 205 lumens, the S2 would be about... 220.



I have an S2, it was a limited edition, FourSevens rates it 180 by their their own specs - just confirmed on the box.


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## beamis (Aug 5, 2012)

moldyoldy said:


> If your perceptions are correct, your NiMH cell was not able to source the continued high current draw of the Zebralight w/o an excessive voltage drop. I have measured the current draw on several of my Zebralights (SC51, H51, etc.) and I routinely observe levels of 2.5+ amps. That is rather a lot for an AA cell. There are not many NiMH cells that can souce 2.5A-3A without excessive voltage sag.



If that's what's happening here we're going to have to re-evaluate everything we know about Eneloops because this was a new Eneloop with less than a dozen cycles on it fresh off the C9000 (after two hours top-off).



moldyoldy said:


> As a quick check, when the light is on high, double click from H1 to H2. If the difference is not obvious, the AA cell is not supplying the necessary current.



This light has several H2 levels, depending on how you program it. All levels are perceptively different.



moldyoldy said:


> In any case, before such tests, the cells need to be fully charged to cutoff. Comparisons are especially troublesome with cells of varying discharge levels. I find remarkable differences between ostensibly similar output lights - all due to cells discharged beyond some 10-20% of capacity, meaning a run time on high of maybe 10 minutes from coming off a charger.



Fresh off the C9000.

All you have to do is have these two lights in the same place at the same time and I guarantee you will not be able to say they are of equal brightness. Some say that cool white looks brighter than neutral white, but don't forget that lumens measure what humans perceive, not the actual quantity of photons.


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## moldyoldy (Aug 5, 2012)

Beamis: some more fishing for explanations... My first caveat is that when I do not understand a perceived problem, it is usually because I have more than one problem. 

as I recall, there were some versions of the C9000 that did not fully charge a cell - requiring at least the 2 hours trickle charge to supposedly bring the cell up to full charge. I had 2 C9000s and disposed of both of them because of inconsistent results between the C9000s. However that 2+ hour difference in trickle charge should not have that significant of an effect in output. 

New Eneloops with less than a dozen cycles? well, agreed, at least they are not new with only a couple cycles. My Eneloops have significantly upgraded capacity after a few cycles.

The light sensor has a sensitivity spectrum. Have you checked on the sensitivity accuracy of the sensor across a visible light spectrum? that data may be on the manufacturer's website somewhere.

Just for my own edification, I pulled out my H51fw and H51f to compare them. To my Mark I eyeball, the "w" version is distinctly dimmer than the "f" version although per spec there is supposed to be only 190-164 = ~30 lumens difference. and not just a little dimmer, a lot dimmer. 

Why not attempt the ceiling bounce test? That is still subject to visual perceptions.

FWIW, I personally do not like the "w" or "warm" version of just about any light brand. too warm and to my perceptions - too dim. Probably the only neutral version that I thought was reasonable was the Fenix LD40.

Good luck!


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## beamis (Aug 5, 2012)

moldyoldy said:


> The light sensor has a sensitivity spectrum. Have you checked on the sensitivity accuracy of the sensor across a visible light spectrum? that data may be on the manufacturer's website somewhere.



I think there might be some confusion about what a "lumen" is measuring (light meters typically read lux, which is 1 lumen/m^2). A lumen is NOT a quantity of light, but a measure of how strongly a human will perceive the light. In other words, lumens are independent of color. Lights of equal lumen ratings will appear equal in brightness regardless of their color. A purely blue light has to generate almost ten times as many photons as a purely green light source to achieve the same lumen rating. A meter designed to measure lux/lumens should not be equally sensitive to all wavelengths because human eyes aren't.



moldyoldy said:


> Just for my own edification, I pulled out my H51fw and H51f to compare them. To my Mark I eyeball, the "w" version is distinctly dimmer than the "f" version although per spec there is supposed to be only 190-164 = ~30 lumens difference. and not just a little dimmer, a lot dimmer.



Then somebody is fibbing on the lumen ratings.



moldyoldy said:


> Why not attempt the ceiling bounce test? That is still subject to visual perceptions.
> 
> FWIW, I personally do not like the "w" or "warm" version of just about any light brand. too warm and to my perceptions - too dim. Probably the only neutral version that I thought was reasonable was the Fenix LD40.
> 
> Good luck!



Lumens are measuring visual perceptions, that's why lights of equal ratings should appear substantially equal regardless of color.


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## srfreddy (Aug 5, 2012)

beamis said:


> I think there might be some confusion about what a "lumen" is measuring (light meters typically read lux, which is 1 lumen/m^2). A lumen is NOT a quantity of light, but a measure of how strongly a human will perceive the light. In other words, lumens are independent of color. Lights of equal lumen ratings will appear equal in brightness regardless of their color. A purely blue light has to generate almost ten times as many photons as a purely green light source to achieve the same lumen rating. A meter designed to measure lux/lumens should not be equally sensitive to all wavelengths because human eyes aren't.
> 
> 
> Lumens are measuring visual perceptions, that's why lights of equal ratings should appear substantially equal regardless of color.



Some people "perceive" cool light to be brighter than neutral light, even at the same lumen levels. Lumens are based on human sensitivity of wavelengths, but light meters are calibrated to different sources of light, which have different wavelength patterns (Fluorescent, incan, led, HID, etc.)



reppans said:


> I can see an obvious diff between the H1 and H2 on my H 51w still no comparison to a Quark S2
> 
> 
> 
> I have an S2, it was a limited edition, FourSevens rates it 180 by their their own specs - just confirmed on the box.


foursevens.com says that the R5 model is rated at 205.


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## moldyoldy (Aug 5, 2012)

beamis: Fibbing? ummm, well, since my perceptions of "brightness" of non-cool-white LEDs are generally too consistent across brands of lights, I would rather wonder about the testing method and equipment used by the manufacturers of any lights with non-white beams, including CREE itself. I doubt that any of us have equipment that could even touch the spectral resolution and accuracy of their light sensors. noting that accuracy and resolution are not the same. Accuracy normally depends on a caibration ratio to NIST, usually a 4:1 ratio, which for a handheld device is usually no more than a yearly calibration cycle. Once upon a time I owned a very expensive photographic light meter (several hundred $$) that would measure ambient light as well as the light from an electronic flash, pulsed or steady-state. The settings were not the same for the different colors!


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## reppans (Aug 5, 2012)

srfreddy said:


> foursevens.com says that the R5 model is rated at 205.



Sure.... no one's doubting that. I was addressing your post here:



srfreddy said:


> The quark AA^2 isn't 181 lumens though.



Beamis and I have the Quark XPG S2 which is 180, and we were comparing output to the 172 lm H51w.


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## moldyoldy (Aug 5, 2012)

beamis: back to your statement that the light output from the Zebralight was continuously dropping after turnon. That alone is a problem. 

I have several Zebralights as well as multiple Fenix, Sunwayman, Nitecore, Lighthound, etc lights. With the exception of the Lighthound AAA lights running single 10440s, all of them will hold a perceived constant output for at least as long as the 3 ANSI minutes. 

Assuming that the output dropping condition is repeatable with different AA cells, then the RMA is fully justified.

I have used the RMA process several times with different vendors including Zebralight with no problem in the results. Only that the process was slow! Good luck!


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## srfreddy (Aug 5, 2012)

reppans said:


> Sure.... no one's doubting that. I was addressing your post here:
> 
> 
> 
> Beamis and I have the Quark XPG S2 which is 180, and we were comparing output to the 172 lm H51w.



But it isn't 180, unless you're telling me that the R5's are brighter than s2's in which case we should be pointing fingers at cree.


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## reppans (Aug 5, 2012)

srfreddy said:


> But it isn't 180, unless you're telling me that the R5's are brighter than s2's in which case we should be pointing fingers at cree.



I'm sure they can tune the driver to whatever they want.... perhaps this is tuned for efficiency and ultimate runtimes.


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## beamis (Aug 5, 2012)

moldyoldy said:


> beamis: Fibbing? ummm, well, since my perceptions of "brightness" of non-cool-white LEDs are generally too consistent across brands of lights, I would rather wonder about the testing method and equipment used by the manufacturers of any lights with non-white beams, including CREE itself.



When I say fibbing, I mean claiming a higher brightness than is reality whether by intention or accident.



moldyoldy said:


> I doubt that any of us have equipment that could even touch the spectral resolution and accuracy of their light sensors. noting that accuracy and resolution are not the same. Accuracy normally depends on a caibration ratio to NIST, usually a 4:1 ratio, which for a handheld device is usually no more than a yearly calibration cycle.



I can't comment on the QC abilities or procedures for any of these companies because I have no idea what they are. I can tell you that I used to work in a shop making aerospace parts with tolerances of 0.0001" and the plant regularly failed to inspect anything, or maybe one part out of a run of 500, and just flat-out lied on their QC certifications. I'm not saying Zebralight or Cree, or anyone else for that matter, does this. I just want to make the point that just because a business _should_ doesn't mean they do.



moldyoldy said:


> Once upon a time I owned a very expensive photographic light meter (several hundred $$) that would measure ambient light as well as the light from an electronic flash, pulsed or steady-state. The settings were not the same for the different colors!



I can't imagine a meter designed for measuring flash output was measuring lumens/lux since film and digital sensors do not respond to light the way human eyes do and such readings would have little meaning for photography.


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## beamis (Aug 5, 2012)

moldyoldy said:


> beamis: back to your statement that the light output from the Zebralight was continuously dropping after turnon. That alone is a problem.
> 
> I have several Zebralights as well as multiple Fenix, Sunwayman, Nitecore, Lighthound, etc lights. With the exception of the Lighthound AAA lights running single 10440s, all of them will hold a perceived constant output for at least as long as the 3 ANSI minutes.



I can't detect the falloff with my eye.


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## Mr Floppy (Aug 6, 2012)

reppans said:


> perhaps this is tuned for efficiency and ultimate runtimes.



42 minutes, I don't think it is for that. I think it may be ANSI ratings with the S2 and non-ANSI ratings with the R5. 

Wow, 2.5A, I'll definitely use an Eneloop then, maybe one of the older ones.


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## reppans (Aug 6, 2012)

Mr Floppy said:


> 42 minutes, I don't think it is for that...



I was referring to the 1277 hrs at 0.6 lms.. I believe that's the longest 4/7s has quoted for a Quark AA2.


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## bbb74 (Aug 6, 2012)

This isn't particularly scientific but I compared the brightness of my sc51w (172 lumens claimed), against a sc51 (200 lumens claimed), a fenix LD25 R4 neutral white (180 ansi lumens claimed), a Quark AA2 R4 neutral white (190 lumens claimed), a H502c (140 lumens claimed), and a Quark AA2 R5 turbo cool white (206 lumens claimed). I just used a digital SLR light meter so with 1/3rd stop increments its not a very fine measurement. I bounced the light off a matte white wall (trying to keep the beam about the same size on the wall by adjusting distance) and then metered an opposite wall 4 meters away.

Anyway ...

The SC51w with imedion is the baseline exposure, and the others are relative to that.

0 - SC51w imedion battery
0 - H502c eneloop
+0.33 - SC51w eneloop (with the occasional flicker up to +0.66 stops)
+0.66 - SC51 eneloop (note this is the cool version)
+1 - LD25
+1 - Quark AA2 nw
+1 - Quark AA2 turbo cw

Visually the ld25 and 4sevens lights were definitely brighter.

Are there any reviews by the same reviewer that have put the SC51 and/or SC51w up against a common fenix or 4sevens light for comparison?


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## srfreddy (Aug 6, 2012)

bbb74 said:


> This isn't particularly scientific but I compared the brightness of my sc51w (172 lumens claimed), against a sc51 (200 lumens claimed), a fenix LD25 R4 neutral white (180 ansi lumens claimed), a Quark AA2 R4 neutral white (190 lumens claimed), a H502c (140 lumens claimed), and a Quark AA2 R5 turbo cool white (206 lumens claimed). I just used a digital SLR light meter so with 1/3rd stop increments its not a very fine measurement. I bounced the light off a matte white wall (trying to keep the beam about the same size on the wall by adjusting distance) and then metered an opposite wall 4 meters away.
> 
> Anyway ...
> 
> ...



From selfbuilt's reviews: 
Quark AA ceiling bounce: 4.6
Zebralight SC51: 10.2
Quark AA^2: 8.0 (This is for the old XRE model)


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## moldyoldy (Aug 6, 2012)

bbb74 said:


> This isn't particularly scientific but I compared the brightness of my sc51w (172 lumens claimed), against a sc51 (200 lumens claimed), a fenix LD25 R4 neutral white (180 ansi lumens claimed), a Quark AA2 R4 neutral white (190 lumens claimed), a H502c (140 lumens claimed), and a Quark AA2 R5 turbo cool white (206 lumens claimed). I just used a digital SLR light meter so with 1/3rd stop increments its not a very fine measurement. I bounced the light off a matte white wall (trying to keep the beam about the same size on the wall by adjusting distance) and then metered an opposite wall 4 meters away.
> 
> Anyway ...
> 
> ...



bb74: Do you recall which mode the SLR light meter was in - matrix, center-weighted, spot? or whichever other modes are available?


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## Mr Floppy (Aug 6, 2012)

bbb74 said:


> 0 - SC51w imedion battery
> +0.33 - SC51w eneloop (with the occasional flicker up to +0.66 stops)



Interesting, which Imedion? I know some of my 2400mAh ones have quite a bit of a voltage sag around 2A.


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## bbb74 (Aug 6, 2012)

moldyoldy said:


> bb74: Do you recall which mode the SLR light meter was in - matrix, center-weighted, spot? or whichever other modes are available?



Of course  I used centre weighted aimed at the same point on the wall, but then went waved it around a bit to see whether I could get the exposure to step down or up 1/3rd of a stop. I tried evaluative too, and that gave basically the same results as centre weighted. Spot I felt was too small an area to sample. Note I also had the lens in manual focus and had everything thrown way out of focus.


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## moldyoldy (Aug 6, 2012)

Mr Floppy said:


> Interesting, which Imedion? I know some of my 2400mAh ones have quite a bit of a voltage sag around 2A.



My measurements on a 10A range for several of the H51 series provided values easily in the 2.5A+ range. I recall the highest current was ~2.7A. All currents were measured on cells just off the charger and swapped out after a few minutes. However my contacts to the battery & casing have been difficult to maintain, so I do not know what the real current draw would be.

FWIW, I had more problems with high-currents when using the earlier 2100mah Imedion (2000mah min) than with the 2400 mah (2250mah min) in Zebralights. The Fenix MC-10 also pulled over 2.4A+ (now discontinued). Also, I have had current-draw problems with Eneloops as well. Not sure if they were the 1500 cycle version or earlier. nevertheless, modern lights or photographic flash units running AA cells are a challenge for any AA cell design. High current or most cycles or slowest self discharge. Balancing all of those characteristics is difficult.


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## moldyoldy (Aug 6, 2012)

bbb74 said:


> Of course  I used centre weighted aimed at the same point on the wall, but then went waved it around a bit to see whether I could get the exposure to step down or up 1/3rd of a stop. I tried evaluative too, and that gave basically the same results as centre weighted. Spot I felt was too small an area to sample. Note I also had the lens in manual focus and had everything thrown way out of focus.



Good choice and verification! BTW, do you recall how much ambient light was in the room at the time? ie: roughly how many f-stops below the flashlight spot light was the ambient light? sorry for the questions.


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## Mr Floppy (Aug 6, 2012)

moldyoldy said:


> FWIW, I had more problems with high-currents when using the earlier 2100mah Imedion (2000mah min) than with the 2400 mah (2250mah min) in Zebralights. The Fenix MC-10 also pulled over 2.4A+ (now discontinued). Also, I have had current-draw problems with Eneloops as well. Not sure if they were the 1500 cycle version or earlier.


Yes, I've had problems with the MC-10 too and certain AA batteries. It's the one with the Osram LED and it's a bit of a battery killer. Cleaning contacts on it seems to help but it still killed a couple NiZn's and 2 Sanyo 2700 (all with high IR > 2.10V afterwards).


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## beamis (Aug 7, 2012)

bbb74 said:


> 0 - SC51w imedion battery
> 0 - H502c eneloop
> +0.33 - SC51w eneloop (with the occasional flicker up to +0.66 stops)
> +0.66 - SC51 eneloop (note this is the cool version)
> ...



Nice test. I think there are two particularly interesting things in this thread: 1) That human eyes, digital camera sensors, camera light meters, and a lux meter all read the the Zebralights as being significantly dimmer than other lights of similar ratings from other manufacturers, and 2) that neutral white lights from other manufacturers do not seem to have the same issue.

While I can't say it's definitive proof that the Zebralight lumen ratings on their neutral white models are a little "optimistic," I think that there's enough subjective and objective observation confirming the initial impressions of many who feel this to be the case to warrant further scrutiny. It looks like the definitive proof is going to have to come from a shootout between some lights in a sphere. Given that I don't have a sphere or many lights, I don't know if this is something I can realistically do. I do have a light meter at the office, but I probably can't take it home.


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## bbb74 (Aug 7, 2012)

moldyoldy said:


> Good choice and verification! BTW, do you recall how much ambient light was in the room at the time? ie: roughly how many f-stops below the flashlight spot light was the ambient light? sorry for the questions.



Not much. When I switched the torch off, the exposure indicator went "off scale", which was -3 stops (I had the camera in M mode, normalised so that a correct exposure of +-0 was for the first test and everything else was relative to that).


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## bbb74 (Aug 7, 2012)

Mr Floppy said:


> Interesting, which Imedion? I know some of my 2400mAh ones have quite a bit of a voltage sag around 2A.



It was a 2400. Its not new (neither was the Eneloop) though. Generally on the C9000 my Imedions always have a noticeably lower voltage during discharges.


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## moldyoldy (Aug 7, 2012)

back to the question of spectral colors: These lights do not represent the same beam spectra which probably affects our perception of the beam intensity. Additionally there appears to be a discrepancy between manufacturers in the terms "warm" or "neutral", as evinced by a casual survey of beamshots in the various reviews posted on CPF, or some surfing on the Internet.

Example: Zebralight rates it's H51w as "warm" and 4200 Kelvin. Fenix rates it's LD40 as "neutral" and about 4000 Kelvin (from the parent Fenix website). I have owned an SC51w and an H51w and find that the beam color is consistent, but far too "warm" for my preference. On the other hand, the single copy of the LD40 that I had (before my nephew absconded with it) seemed no where near as "colored", meaning excessively "warm" as the Zebralight definition of "warm". I could almost like the beam color on the LD40. That represents nearly no relationship to the rated Kelvins of the beam color except that they are not "cool white".

caveat: I have a strong aversion to "warm" or "neutral" colored beams. Such colors remind me far too much of the light from a Maglite with dying batteries - which is what I grew up with. I strongly prefer a cool white beam color. Any light with a neutral or warm beam represents a very narrow niche usage for me, hence I own only one of them.

The point for this thread is related to the listed testing methods to date, none of which take in to account the spectral color of the light, including the Mark I eyeball. All of the sensors described in this thread so far have a spectral sensitivity curve which may or may not have a limited correction back to - which Kelvin color? Unknown. For ad-hoc testing, they are OK to better identify questions regarding low-performing lights. My point is that if the light beam emanating from a tool has an inadequate strength for your purposes, change the tool. That might be via an RMA, or changing tools or manufacturers.


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## bbb74 (Aug 7, 2012)

Moldyoldy. I agree that different tints/spectra may affect our perception of brightness. However these lights have lumen ratings that we are comparing, and lumen measurements take into account the light's spectra. If light "A" and "B" both have 200 lumens, they should appear pretty similar in brightness as the lumen measurement already takes into account most of the spectral difference between them.


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## Mr Floppy (Aug 7, 2012)

bbb74 said:


> If light "A" and "B" both have 200 lumens, they should appear pretty similar in brightness as the lumen measurement already takes into account most of the spectral difference between them.



I believe that to account for the spectral difference, the light wave either side of the light sensitivity curve of the human eye are weighted up. Thats if the lumens is a photometric reading (i.e based on the visible light). I believe that's the basis for the light meters. It's probably different in the lab, so if a lot of the light of the cree xp-g warm white falls mainly to the red, it is given a relative lumens in the lab, which probably measures the power of the radiant flux, apply the Judd-Voss correction, etc. I don't know, not an expert in the slightest and may have read things wrong.


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## moldyoldy (Aug 8, 2012)

bbb74 said:


> Moldyoldy. I agree that different tints/spectra may affect our perception of brightness. However these lights have lumen ratings that we are comparing, and lumen measurements take into account the light's spectra. If light "A" and "B" both have 200 lumens, they should appear pretty similar in brightness as the lumen measurement already takes into account most of the spectral difference between them.



As a flashaholic, I agree with you! absolutely!

However my primary military experience with the signal spectrum, some of my former engineering work (as an EE) where I ran an electrical and mechanical calibration lab in a military/industrial plant, and my experience as a serious "hobbyist" photographer (2000+ rolls/yr) attempting to go pro/independent where I worked independently as a sports and wedding photographer for many years, suggests otherwise. In those endeavours I discovered that standards in some areas were very tight, in other areas there were almost no standards except the basic laws of physics. IOW, Any attempt to compare at our equipment level was doomed to failure. Hence we individually or collectively decided on a "standard" and evaluated accordingly. But we knew that we possibly were in "never-never land".

IOW, given the current lack of knowledge of accurate emission spectrums from LEDs and how those emissions were measured, decide on whatever you want with whatever tools you have available, but know that comparisons are fraught with pitfalls and traps. 

a moldyoldy...


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## moldyoldy (Aug 8, 2012)

Mr Floppy said:


> I believe that to account for the spectral difference, the light wave either side of the light sensitivity curve of the human eye are weighted up. Thats if the lumens is a photometric reading (i.e based on the visible light). I believe that's the basis for the light meters. It's probably different in the lab, so if a lot of the light of the cree xp-g warm white falls mainly to the red, it is given a relative lumens in the lab, which probably measures the power of the radiant flux, apply the Judd-Voss correction, etc. I don't know, not an expert in the slightest and may have read things wrong.



a good thought process. However for an example of a condition where that thought process has difficulty, go in to any large old industrial plant that uses sodium vapor lamps for lighting. These lamps have almost a single-line spectra and drive light metering systems crazy. Why? Because most light meters are expecting a relatively broad spectrum/spectra of incoming light. Hence the reason why GE developed their multi-vapor lights to correct this design deficiency. However some locales near observatories or airline flight paths will still used sodium vapor street lights because the perceived illumination is much lower, both to human eyes or to instruments.


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## beamis (Aug 12, 2012)

moldyoldy said:


> a good thought process. However for an example of a condition where that thought process has difficulty, go in to any large old industrial plant that uses sodium vapor lamps for lighting. These lamps have almost a single-line spectra and drive light metering systems crazy. Why? Because most light meters are expecting a relatively broad spectrum/spectra of incoming light. Hence the reason why GE developed their multi-vapor lights to correct this design deficiency. However some locales near observatories or airline flight paths will still used sodium vapor street lights because the perceived illumination is much lower, both to human eyes or to instruments.



Please forgive me if it comes across the wrong way, but are you suggesting that even when a light appears dimmer than another to the naked eye, reads dimmer in camera light meters, photographs dimmer with CMOS sensors, and reads dimmer using a lux meter, it's still possible that our eyes and instruments deceive us and the light is in fact equally bright?


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## moldyoldy (Aug 12, 2012)

beamis said:


> Please forgive me if it comes across the wrong way, but are you suggesting that even when a light appears dimmer than another to the naked eye, reads dimmer in camera light meters, photographs dimmer with CMOS sensors, and reads dimmer using a lux meter, it's still possible that our eyes and instruments deceive us and the light is in fact equally bright?



nope, nothing like that. Only that it is often difficult to quantify the "dimmer" difference. Comparisons w/in a brand lineup are less troublesome. Comparisons between brands become more difficult because of the obviously different standards used. eg: my example above comparing Kelvin numbers and my perception of color between Zebralight and Fenix for a non-cool-white beam color. 

Ultimately the user decides whether a flashlight provides sufficient illumination for the tasks at hand, not the specs or the manufacturer. If a flashlight fails to meet your needs, change it!


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## moldyoldy (Aug 12, 2012)

FYI: There is a very informative series of posts by UnknownVT on the subject of LED beam colors and human perceptions in this CPF thread:

http://www.candlepowerforums.com/vb...ed)-Quark-AA2-Neutral-White-Comparison-Review

The thread may refer to obsolete flashlights, but the color comparison information is very useful. Just about every post by UnknownVT provides considerable detailed information. Note his use of color desaturation to determine brightness comparisons. Also, the links in posts #5, #7, #17, #19, #29, #36, and #39 are so useful that I bookmarked that entire thread in my browser.

My complements to UnknownVT!


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## Mr Floppy (Aug 13, 2012)

I have the newer H51w now so I can run some readings. First of all, I have a cheap light meter. Secondly, the light box I built recently is having its first run. It is a 30cm cube (a foot). Unfortunately it is a bit too shiny inside so it does affect the reading depending on where the hotspot is aimed. The H51 was hard to mount as the hole was designed for your regular lights, not angle ones. I had to aim the hot spot as well as I could at the same place.

So, my readings are 77 for the H51w and 94 for the Fenix LD10 R4. Using selfbuilts figues here, here is comparitive result. His LD10 R4 had a lightbox reading of 73, compared to mine of 94. So with this, a comparitive reading is 59 on selfbuilts figures. Which is a bit better than the Nitecore D10 Q5 cool, which has a stated lumens of about 130. 

Now another caveat, The LD10 R4 reading I think was a bit too far out. If my readings translate to selfbuilts figures, then LD20 R4 should give me a reading of 104. Well it didn't. It was much lower at 99. I've previously done the same test with a ceiling bounce and it was much closer to selfbuilts figures so I'll have to go back to that I think until I calibrate the light box against selfbuilts figures, (move all the stuff out of the toilet ...)

Anyway, to my naked eye, it looks quite bright, much brighter than the TK20. What I think could throw people off is the hot spot. The TK20 hotspot was visible when shone directly into the middle of the H51w hot spot but it is throwy. It looked as bright as my L2D Q5, which has a comparable hot spot, maybe just a bit smaller. That is rated at 180 lumens and in my light box, it gave a figure close to that of the H51w at 79-81 but at that stage, the holder started to move and I had to hold it with my hand. 

Current draw at the tail cap was 2.2A if curious. Tried a few batteries and only the Eneloop managed to get H1 mode.


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