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

  1. #31

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    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.

  2. #32

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

    Have you guys perhaps have a dud?

    Here's a review of the SC51w from a year back.
    http://www.candlepowerforums.com/vb/...-beamshots!%29

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

    Quote Originally Posted by reppans View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Here's my H51w compared to a Quark AA2 S2


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

    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.
    Last edited by beamis; 08-02-2012 at 09:10 AM.

  6. #36

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    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.

  7. #37

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

    Quote Originally Posted by beamis View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Quote Originally Posted by Mr Floppy View Post
    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.
    Last edited by beamis; 08-02-2012 at 06:31 PM.

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

    Quote Originally Posted by Mr Floppy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Quote Originally Posted by beamis View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    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.
    Last edited by beamis; 08-02-2012 at 07:11 PM.

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

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

  13. #43

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    He said earlier he had an XPG S2

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

    Quote Originally Posted by beamis View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

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

    Quote Originally Posted by reppans View Post
    He said earlier he had an XPG S2
    The R5 AA^2 is rated at 205 lumens, the S2 would be about... 220.

  17. #47

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    Quote Originally Posted by moldyoldy View Post
    ...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

    Quote Originally Posted by srfreddy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Quote Originally Posted by moldyoldy View Post
    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).

    Quote Originally Posted by moldyoldy View Post
    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.

    Quote Originally Posted by moldyoldy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

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

    Quote Originally Posted by moldyoldy View Post
    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.

    Quote Originally Posted by moldyoldy View Post
    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.

    Quote Originally Posted by moldyoldy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Quote Originally Posted by beamis View Post
    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.)

    Quote Originally Posted by reppans View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    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!

  23. #53

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    Quote Originally Posted by srfreddy View Post
    foursevens.com says that the R5 model is rated at 205.
    Sure.... no one's doubting that. I was addressing your post here:

    Quote Originally Posted by srfreddy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    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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    Quote Originally Posted by reppans View Post
    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.

  26. #56

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    Quote Originally Posted by srfreddy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Quote Originally Posted by moldyoldy View Post
    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.

    Quote Originally Posted by moldyoldy View Post
    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.

    Quote Originally Posted by moldyoldy View Post
    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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    Default Re: Zebralight H51w is too dim. Is the H51 cool white better for trail running?

    Quote Originally Posted by moldyoldy View Post
    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.

  29. #59

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

    Quote Originally Posted by reppans View Post
    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.

  30. #60

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    Quote Originally Posted by Mr Floppy View Post
    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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