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Thread: What? PA10 is so low power with 14500?

  1. #1

    Christo Pull Hair What? PA10 is so low power with 14500?



    Okay, but how the heck JETBeam can claim 650 lumens with a single 14500?! This is shocking to see! I wanna hear some of your comment~

  2. #2
    Flashaholic* dc38's Avatar
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    Default Re: What? PA10 is so low power with 14500?

    i think the 650 lumen rating is the otf rating with a freshly charged lion to 4.2 V. Also, that lux rating is just about the same that I measured with a few different lux meters at 1 foot. notice that the guy says in the video "highest setting", which im assuming is a "times 100" scale. at a foot away~, he would get 33,900 lux, right? from a meter away, i believe i get a rating ranging from 2,800 to 3,800 lux depending on cell voltage, but idr lol
    Last edited by dc38; 08-05-2012 at 08:00 AM.

  3. #3

    Default Re: What? PA10 is so low power with 14500?

    How do you measure the OTF lumen? I am not expert in this and so can you please explain?

  4. #4
    Flashaholic* dc38's Avatar
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    Default Re: What? PA10 is so low power with 14500?

    Quote Originally Posted by CYMac View Post
    How do you measure the OTF lumen? I am not expert in this and so can you please explain?
    Unless you have access to a good integrating sphere (big white ball that captures total emitted light with a sensor) it is damn near impossible to figure out the exact lumen rating. The closest thing you might be able to do is to measure the LUX at 1 meter, figure out the viewing angle, (all from the LED without the reflector or optics i believe) and use some formulas or a prescripted website calculator and plug in your measurements. The moment you activate the LED , measure the lux at that level as well as the specs (angles) of the LED. OTF is the initial output before dropping due to heat or voltage/ current loss, you can calculate the LED lumens this way. Coupled with the reflector and optics, the output may be a little less because of loss of light. *btw, ANYBODY please feel free to correct me if I'm stating something completely incorrect, as I consider myself a newbie as well )

    **ALSO, Very few Chinese light manufacturers will state that the MAX output are OTF lumens, they just slap ANSI on the label and lead their consumers to believe that "MAX OUTPUT" was measured at ANSI standards. It only stands to reason that almost NOTHING can run at full blast past initial activation, as the current / voltage start dropping the moment you turn the light on.**
    Last edited by dc38; 08-05-2012 at 03:40 PM.

  5. #5

    Default Re: What? PA10 is so low power with 14500?

    Quote Originally Posted by dc38 View Post
    Unless you have access to a good integrating sphere (big white ball that captures total emitted light with a sensor) it is damn near impossible to figure out the exact lumen rating. The closest thing you might be able to do is to measure the LUX at 1 meter, figure out the viewing angle, (all from the LED without the reflector or optics i believe) and use some formulas or a prescripted website calculator and plug in your measurements. The moment you activate the LED , measure the lux at that level as well as the specs (angles) of the LED. OTF is the initial output before dropping due to heat or voltage/ current loss, you can calculate the LED lumens this way. Coupled with the reflector and optics, the output may be a little less because of loss of light. *btw, ANYBODY please feel free to correct me if I'm stating something completely incorrect, as I consider myself a newbie as well )
    Thanks so much, were you the one who posted some reviews with that big white ball and the lux meter? or someone else? I saw some reviews done with that in the review section before and those test were quite insane!

    Does it matter if the room is pitch black or not when testing these things as well?

    How come some test with "ceiling bounce"? what is the difference?

  6. #6
    Flashaholic* dc38's Avatar
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    Default Re: What? PA10 is so low power with 14500?

    Quote Originally Posted by CYMac View Post
    Thanks so much, were you the one who posted some reviews with that big white ball and the lux meter? or someone else? I saw some reviews done with that in the review section before and those test were quite insane!

    Does it matter if the room is pitch black or not when testing these things as well?

    How come some test with "ceiling bounce"? what is the difference?
    You're very welcome! Unfortunately, I don't have an integrating sphere or a nice lux meter, though there are many members here who have access to one (or have created their own..i.e. Selfbuilt).

    Regarding ambient lighting, it is most desired to have as little ambient lighting as possible for the most accurate results, as a little bit of outside light MAY disrupt a reading especially on a homemade integrating sphere.

    A ceiling bounce is VERY useful for gauging the true amount of light coming out of the flashlight. When you stare at the hotspot, it's very hard to determine exactly how much light is coming out, because of the varying hotspot sizes/intensities, as well as the spill. Many people don't realize that the spill counts as part of the lumen rating, because many times, the spill isn't noticeable compared to the long throwing hotspot. In a ceiling bounce, you can generally visualize the amount of light coming into the room. (you'd never look directly at a lightbulb in a lamp to see how bright it is, you'd look at the light bouncing around the room and how clearly you can see everything).

    **note** you can also use a diffuser to gauge the general light output of a light, but there will be greater lumen loss than with a ceiling bounce as much of the light is trapped in the diffuser. Again with this test, try not to look at the diffuser on a light because it'll pretty much be the same as staring down the barrel of an light in operation.

  7. #7

    Default Re: What? PA10 is so low power with 14500?

    Great info there! Now it's getting a bit more clear. So the more accurate way to measure the lumen of a light should be done with the sphere method but then the secondary thing you can do without one is to do the ceiling bounce since it will capture the light surrounding it as well. Um.. make sense to compare a few results first as well. Measuring light is not easy~

    Thanks again for the info!

  8. #8
    Flashaholic* dc38's Avatar
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    Default Re: What? PA10 is so low power with 14500?

    Quote Originally Posted by CYMac View Post
    Great info there! Now it's getting a bit more clear. So the more accurate way to measure the lumen of a light should be done with the sphere method but then the secondary thing you can do without one is to do the ceiling bounce since it will capture the light surrounding it as well. Um.. make sense to compare a few results first as well. Measuring light is not easy~

    Thanks again for the info!
    Also, dont forget, a ceiling bounce may also be inconclusive because of the size and intensity of the spill. you can generally eyeball the amount of ambient light from a ceiling bounce. if it lights the room up more, chances are it will have a higher lumen rating than another light that doesnt light up much. tints make a little difference as well. generally, cooler tints are brighter because of light frequency as well as efficiency from absence of tinting phosphers that absorb some light.

  9. #9

    Default Re: What? PA10 is so low power with 14500?

    Thank you ! That is informative~ but then if you see the lux meter reads A is having a much higher number than B then it is for sure brighter than B anyway, at least now we know the reading can put the lights into a ranking ladder as well, haha!

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