Fun with light beams

We tried experimenting tonite with some of our throwers. We were trying to capture some cool beam shots. Unfortunately it was pretty bright conditions tonite with the moon almost full, so the shots almost look like daytime. But the shots still look kind of cool I think.
The exposure is slowed down a good amount of course. Standard settings you could still see the beams, but these shots were just for fun.
We’ll try again with more variations when we find a night with little ambient light.
So the players were - TN31mb, TN31, TN31, TK75, & BTU. All 5 of these shots were done at the same settings.
Here they are -
TN31mb. This one was a little blurry, must have moved the camera some -

Now BTU -

The TK75 -

TN31, TN31mb, TN31 -

TK75, TN31, TN31mb, TN31, BTU -

nice pics. way better than i can do

Rd,those are some awesome shots thanks!If a UFO lands in texas tonight it's your fault lol.The TN-31mb is visibly a crazy thrower and the BTU is impressive as well for a multi emitter light.

Thanks for sharing. That’s a serious arsenal of lights you have there.

If we get an alien invasion I know who to blame. Nice shots though.


Yeah we had a nice collection out there between brother and I. I didn’t even have to break out the SR90. We intend to play some more when the conditions are darker. Maybe try some more variations. The moon was so bright that we didn’t need any lights to see around, and there was no man made lighting out there in the park. Made it difficult to increase the beam strength and not the surrounding light.
We had fun playing around though.

Great pics (great flashlights). :smiley:

Specs for the first photo?


130,000 cp
1273 meters to 1 lux illumination
1147 lumens
and with a ruler and eyeballing your photo gives me ~1.5 degree beam angle.

Sound right?

Very cool!!

Not quite. About 436kcd, 660m to 1 lux, 741 lumens. I think 1.4 degree angle.

Great shots! I can't get over how white the TN31mb is compared to the others. They all look blue but that is as pure a white as it seems it could be. Is it that way in person, too?

Nice pics. What sort of exp did you need to use to get them?

Thanks, rdrfronty.

At HD none of the flashlights posted all of lumens, cp, watts, beam angle and beam throw. Maybe you got three and maybe a different three for each light.

There are formulas to fill in the gaps but they don’t seem to totally work.
One manufacturer said he uses a light meter to read beam throw; no formula. The other manufacturers I asked kept mum.

Usually a light meter is the probably the easiest and most accurate way of determining throw.
Calculating with watts changes on the emitter (if it is incandescent, halogen, flourescent or LED and even still it would change on different LEDs).
When you say cp, do you mean candlepower? If so, it should be calculated in candela (cd).

I have used meters to measure the lumens in a lightbox and the same meter to measure my lux on the TN31mb.
You do understand only the first light shot and the center of the other shots are the TN31mb? The other surrounding blue looking beams were standard TN31’s with roughly 125K and 1100 lumens. The very outside ones were the BTU with about 125K and 2850 lumens, and the other side the TK75 with about 94k and 2925 lumens.
These are all numbers via my own testing.

ISO 160, aperture f4.5, exposure 30sec. Camera is brothers Sony DSC HX100V.
We did the exposure so long because the conditions were so light it allowed a much better contrast. When the moon is hiding on our next attempt we should be able to go with a shorter exposure.

Cool as hell. :wink:

IIRC, the highest luminous efficacy I’ve heard of are these sodium vapor lights - 260 lumens/watt. And a candle comes in at 0.3 l/w.

Yes, strictly I should put in the cd = 1.02 x cp conversion but a 2% difference in this business may be down in the noise. :smiley:

Thanks. Think I might have to give this a try.