Candlepower

[**DONOTDELETE**]

I am interested in finding out how manufacturers 'calculate' their outrageous claims for beam candlepower or peak beam candlepower. Lumens or footcandles I can measure/calculate.. How do I verify a 1 million candlepower claim?

 

[brightnorm]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by *something ridiculous ?:
Lately, we've found that even Lumen ratings can be manipulated to about 2.5 times magnification too.
<HR></BLOCKQUOTE>

Hi LL,

That's one I wasn't aware of. Can you explain please?

BN

 

[Brock]

CAD Research, I don't think they use any "standard" method of obtaining CP ratings. Believe me this drove me nuts, so I started my web site because of it. I don't claim to know exactly what I am doing, but I measure each light I buy or get the same way, so I can compare them to one another. I have found in the same class, say halogen lamps, they pretty much follow the wattage used. So a 100w light is about twice as bright was a 50w light. I am just now getting in to the big 12v spotlights, so it will be interesting to see how they compare to the other lights I have.

 

[lightlover]

brightnorm,
I can't properly remember the full details of what lights they were, but two in particular had impossibly over-rated Lumen values. One was an inexpensive Chinese "SureFire copy", and another was brightnorm's famous Topic:
Review: TRG AURORA- Good light, mistaken claims @ http://www.candlepowerforums.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=3&t=001022

where incredible claims were made for the "TRG Nightfighter". (I'm surprised you don't recall that one, old chap !!)

Even when using a true Ulbricht (Integrating) sphere, it's possible to apply "odd" methods of measurement, calculations and arcane formulae to the readings. It's also possible to do tricky things like measuring the output of the lamp without a lens in front of it, or without a reflector, (so no losses due to those) and some other disreputable touch-ups which mislead.

Needless to say, SureFire don't exaggerate like this - their company policy is to understate. They also take Lu output from the flashlight in "actual use" configurations.

One of the best sites for light measurement details is "The International Light Handbook", @ http://www.intl-light.com/handbook/ch07.html
(Can be downloaded too, and well worth it.)

lightlover

 

[**DONOTDELETE**]

Check this out http://www.knifeart.com/surflasfaq.html

 

[lightlover]

Welcome aboard CAD Research

The only way to verify such claims is by writing to the manufacturers Marketing department ......

We have had a case where a flashlight beam had one point which measured as 8 times more light than another point.
This was when it was being kept at a constant distance, but moving the sensor around in the beam.
(I.E. only from left to right and up/down.)

If you searched around at different distances as well, you might find even more disparate levels of light.
Candlepower ratings aren't very useful to anyone except people who like to manipulate statistics.

Lately, we've found that even Lumen ratings can be manipulated to about 2.5 times magnification too.

lightlover