Creating a Standardized, Quantitative Method of Evaluating Light “Utility”

One of the brightest "portable lights" I can think of is a laser pointer, which delivers a very high intensity beam, but not enough light to see by. Tested against almost any flashlight, a measurement of intensity would deem the laser pointer the "best" portable light. To truly gauge the performance of a light, beam area needs to be normalized, with an average brightness measured over a specified surface area and distance. This provides a comparison of the true light output of the device, taking into account both the output of the light sources, as well as the actual flashlights' efficiency (lumen collection and "collimation" or projection). Here's a link to the first experiment I have tried. (I call it the "Staple's 94 brightness" test)

http://home.comcast.net/~rasanford1/Flashlights/Quantitative evaluation of light utility.doc

Please add your perspective as to how I/we might improve upon this, or let me know if you feel there is a major flaw in my thinking.

Thanks,

Hitec

This is already in place. Total light output is the "lumen" you mentioned. Peak beam intensity is candlepower or lux (different units that measure the same thing). The shape or distribution of the beam is the beam shape, beam pattern, or (especially in the case of bare LEDs) radiation pattern. The "lumen collection" you mentioned is bulb lumens for incans or emitter lumens for LEDs as compared to the actual lumen output of a real flashlight, called torch lumens.

You might want to do a little reading here.

+1

"Lumens" and "lux" are the two readings which will tell you the most about a light. Lumens measures the total output, lux measures the "throw" of the light.

"Utility" is also extremely subjective. For example, I occasionally use my EDC light for 3 or more hours at a time before a battery change would be possible. So for me, the extended run-time of a 2 cell light might cause me to consider it more useful than an equally bright or brighter 1 cell light. Similar cases can be made for Color temp., CRI, spot/flood beam type, form factor and size,... light output is important, but it's by no means the only consideration.

I've come to realize that there can not be one standard method for measuring utility. Some people find a very floody beam with a wide, bright spill at the expense of throw to be the most useful. Other find that they need much more throw. That said, the best option IMO is to have spill and hot spot lux values provided along with a beam shot. The beam shot is important because it lets you know the relative size of the spill. If you have the beam shots of competitive lights, that's even better.

Marduke, you are always there with concise answers and keen observations. If you have a focus beam light, does that convert lumens into lux?

popcornpicker said:

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If you have a focus beam light, does that convert lumens into lux?

Click to expand...

I guess the following applies to you, too.

TigerhawkT3 said:

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You might want to do a little reading here.

Click to expand...

Tigerhawk: I've tried your links, but can't get anywhere. It may be my firewall or pop-up blocker.

popcornpicker said:

Tigerhawk: I've tried your links, but can't get anywhere. It may be my firewall or pop-up blocker.

Click to expand...

It's probably the popup blocker. CPF automatically opens posted links in a new window. I just double-checked, and the link works for me.

You can try Ctrl+click (overrides popup blockers, IIRC), opening in a new tab, or copying the shortcut and pasting it into an address bar.

I hope some of that helped.

popcornpicker said:

Marduke, you are always there with concise answers and keen observations. If you have a focus beam light, does that convert lumens into lux?

Click to expand...

The short answer is no, you can't convert. Lux measures the intensity of the beam at that point, usually the hotspot at 1m. Some people also measure the spill area. These two numbers are common to find on CPF because light meters are rather cheap, and it gives you a decent idea of the beam brightness and profile.

Lumens measures the total output, disregarding the beam shape (throw or flood), but requires a >$10000 integrating sphere.