Lumen Density

In the search for the best flashlight for my needs, I found it natural to think in terms of trying to find as a bright a light possible in the smallest package. Has anyone tried to compile a data base that expresses lights in terms of Lumen Density?

:welcome:A lumen is a measure of total light output. How you focus it is your concern. Something like a laser would have a splendid density, but might be a little hard to walk around by.

Lunens per overall cubic square inch of an individual light would be a way to look at it. Some of the AAA or smaller lights using LiIon's would be right up there.

Bill

Sounds like you're wanting lights listed with candle power measurements, which are taken at the center (brightest) portion of the beam.

ToeMoss, you there?

Bill

Bullzeyebill said:

Lunens per overall cubic square inch of an individual light would be a way to look at it. Some of the AAA or smaller lights using LiIon's would be right up there.

Bill

Click to expand...

Yes, that's what I had in mind. I would think lumens/cubic inch would be useful as many manufacturers already know the lumen output and dimensions of the lights are readily available. I may be wrong, but it seems that Candle Power measurements, while certainly useful, would be an inferior way of measuring flashlight performance. Lumens, it seems, give you a broader idea of what the light is capable of. Some portion of the light is focused, some is spilled. A light has a combination of these two traits and so only listing candle power leaves out all information regarding spill correct? It would'nt say anything about the size of the central light either.
Lumens is not perfect either, but as it does speak of total light, i figure it will all go (nearly) to either the focused portion of the beam, or the spill. Both are good for me. How that split actually occurs would be a mystery to some degree, but one could probably know what to expect from any given manufacturer.

I read the title and though you ment lumen density as in a light source. For example, a Laser has a high lumen density at the source buy less overall output.

You could have asked for the smallest bright light.

The smallest bright light is probably the Drake or Draco. Tiny as in smaller then a AA battery.

:welcome:

If by lumen density you mean

(lumens output)/(volume of the flashlight)

you'll come up with lights with very short run times like the Draco noted by Gunner12 above or (for the cheapskates) Kyle's buckle light or some such. Most of these won't go much past 20 minutes.

If you care about run time, then you need to look at total light output density, e.g.

(lumens-hours)/(volume of light)

where lumen-hours is the area under the output runtime curve of the light (integrated numerically or eyeball estimated from the runtime curve) divided by the volume of the flashlight body. In that case, I suspect you'd find one of the current generation Fenixes running Li-ion to be tops as Fenix appears to have the most efficient drive circuits among production lights.

BTW, when I compare light numbers, I look at the lumen-hours of the light per battery as a useful measure of design efficiency (which I value).

Your best bet as Bullzeyebill pointed out is a AAA form factor. Your runtime is going to suck of course but it's possible to get a lot of lumens out is you have a Li-Ion power source, and to minimize the denominator (cubic inches), use the smallest form factor available. You can always go exotica and use even smaller Li-poly cells but I'm guessing that's not what you're looking for.

Hey all,
Thanks for all your answers, it's all been very helpful. Seem like a great forum!! That Draco looks like a nice light, how bright is it though? I couldn't find any specs.
As for compact lights, I've got a proton which is a pretty cool light, but it wasn't quite as bright as I'd like, so after pouring over a lot of specs, I settled on a C3 Centurion by Surefire with a P91 lamp. I like it a lot but wonder if I made a good decision? After reading up on this site, I decided I'd like to go with some rechargeable batteries as they'd save money in the long run. I decided on a pair of 17500's Li-Ion batteries. Upon further reading I learned that the P91 and these batteries are not a good fit, so I figured that I really had no choice but to find a light that work with these batteries that are on the way. So....found a Surefire 9P that I think ought to do the job. I think, if I understand correctly, that to get the most out of that flashlight with the 17500 Li-ion batteries, I should use an EO9 lamp. Am I on the right track with that? Oh, by they way..what should I do with the two P90 lamps that will be left over if I go with the EO-9 lamp?

Stay with the P90 LA and two 17500 LiIon's. It actually puts out about 200 lumens and lasts longer at full brightness than 3 CR123's.

Bill

I've read that the Draco was 160 lumen in a floody beam pattern.

If you like LEDs, you could also find many P60 sized drop-ins that will take up to and over 9V. But most are nowhere close to 200 lumen out the front.