flashlight intensity & options

keithwins · Jan 3, 2017

Hello there,
I've got to test ceiling-mounted light sensors: I do so by shining a flashlight on them. I generally buy fairly low-price zoomable LED flashlights with CREE XM-L T6 LED's in them, typically rated in the 600-1000 lumen range (tested with a cheap light meter at about 600 lumen output). I've been running them with three aaa cells, but expect to be changing over to 18650's soon.
It seems to me that, in terms of light-on-target, a zoomable flashlight is the way to go: my target is typically around 1/2" in diameter, from 8'-20' away.
It might be good to have a little more light available, but it doesn't seem like there are a lot of options: any ideas? It seems to me that it might make more sense to double- or triple-up the lights themselves (that is, use more flashlights), but I'm wondering if anyone has any other ideas? Sometimes I hold the light over my head, in which case it might be 2' away instead of 10' away (sitting on the floor), but... it's not that fun to hold my arm over my head for a minute or two. I think that, even with zoom, light intensity drops off as the square of distance: is that true in this case?
Thanks for any help in understanding.

scianiac · Jan 4, 2017

What you are looking for is throw, measured in Kcd (or ANSI distance in meters). You are correct that zoomable flashlights generally have very good kcd for their size, although most of the stock cheap ones are really not that impressive due to poor emitter and driver. It would not take much at all to beat those cheap zoomies in throw. If you use 18650s you have many many options that will provide the throw, and therefore lux at your target 10' or much much further away.

lightfooted · Jan 5, 2017

keithwins said:
Hello there,
I've got to test ceiling-mounted light sensors: I do so by shining a flashlight on them. I generally buy fairly low-price zoomable LED flashlights with CREE XM-L T6 LED's in them, typically rated in the 600-1000 lumen range (tested with a cheap light meter at about 600 lumen output). I've been running them with three aaa cells, but expect to be changing over to 18650's soon.
It seems to me that, in terms of light-on-target, a zoomable flashlight is the way to go: my target is typically around 1/2" in diameter, from 8'-20' away.
It might be good to have a little more light available, but it doesn't seem like there are a lot of options: any ideas? It seems to me that it might make more sense to double- or triple-up the lights themselves (that is, use more flashlights), but I'm wondering if anyone has any other ideas? Sometimes I hold the light over my head, in which case it might be 2' away instead of 10' away (sitting on the floor), but... it's not that fun to hold my arm over my head for a minute or two. I think that, even with zoom, light intensity drops off as the square of distance: is that true in this case?
Thanks for any help in understanding.

I would think that getting something like a Solarforce or some other P60 format light set up specifically for this would have better results. There are lenses that can be had to focus the light into a nice narrow beam even though my first dropin for my Surefire was an old XR-E that threw the beam out well past 100 meters. Just shining it onto a wall now about 10 feet away, the hot spot fits inside an area about the size of a small dinner plate. It's only about 220 lumens but you can probably find some combination that gets you as much light as you want. My Olight M21X2 also throws out to a decent distance and with it's XM-L2 manages over 700 lumens.

Fenix is making a light now that has an adjustable beam. 900 lumens from an XP-L in a single 18650 format. FD41 is the model.

JLeephoto · Jan 5, 2017

I can't think of a reason to double up lights when you can likely get all u need from a single 18650 thrower. You might also consider headlamps if you find yourself holding a light at head high all day. The Nitecore HC30 runs at 1000 lumens and is more throwy than a lot of the headlamps out there.

flashlight intensity & options

keithwins

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scianiac

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lightfooted

Flashlight Enthusiast

JLeephoto

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