For example, put DC-Fix on a mule. It has virtually no effect. Then put it on a thrower, and it has a much bigger effect. The more collimated the beam, the more it can be messed up by diffusion film. But making a mess out of something which is already a mess… isn’t very noticeable.
With measurements of a bunch of lights, it would be possible to generate a curve and figure out the math. But for now, I really don’t know. The effect is probably something like sqrt(candelas) or sqrt(cd/lm). Except, instead of a square root, it’s probably a different power. Like math.pow(cd, 0.95) or math.pow(cd/lm, 0.75) both get fairly close to the numbers in the OP.
Not really, that question is about loss of collimation (amount of collimated light turned into scattered light), not about light loss.
Actually, my feeling is that the light loss by a diffuser of a floody and throwy beam should be the same.
I also would like to see the numbers for throwers and flooders but, as ToyKeeper said, the visual effect on a flooder is negligible.
Diffusers are very nice but the drop in throw has 2 effects. First you want to increase output to increase throw again. It’s totally subjective but it’s what you want to do, so one should have more lumens available… Maybe one can get used to it after a few minutes but I didn’t try it.
Second, lots of flood are inconvenient to illuminate farther away so I don’t keep it permanently on the flashlight. I carry several pieces for different flashlights in the wallet; sticking the right one on the flashlight takes less than 1 minute. Removal is also easy and it doesn’t leave dirt on the glass. Dc-fix can be reapplied several times. I glue them back in the plastic cover that comes with it in the wallet to not lose the adhesive.
I wonder what’s the light loss with (multilayer) AR coated lens.
Such lens has refractive index of the material next to DC-FIX close to that of air. That would probably negatively impact efficiency……
I noticed that such diffusor foils/lenses make the outer rim of the spill brighter than the inner parts of the spill. I find this a little bit distracting. The loss in throw is also quite noticeable.
A related question: if you’ve bought a type of diffusion film that is NOT adhesive on one side, and the light you’d like to use it on seems to be permanently shut (probably glued together inside) is there a recommended type of glue that one could use very lightly around the inside of the bezel to attach the film that is somewhat easy to remove, relative to other kinds of adhesive?
I really don’t want to ruin an expensive light experimenting with different kinds of glue, so ideas are welcome. Thank you!
Probably not. The trick is to put a small drop of glue in the center, then carefully place the filter on top of it, squish out the glue (make sure there are no air bubbles) and then harden the glue with a UV flashlight. You’ll get an even, invisible and permanent bond.
Oh, OK. Thank you for the info. I think I’d rather use something that is removable in case I ever want to resell the flashlights, as the next owner probably won’t want anything but the stock configuration. Maybe hot glue or silicone? Not sure…need to keep looking.
I used Elmer’s glue for my Zircon minus green filters. One small drop each on opposite side - right where the film meets the bezel. The glue then hardens. Worked to perfection - much, much better and firmer hold than I had expected.
Another advantage of Elmer’s glue is you could (gently) remove the film afterwards by breaking the hardened glue gently. One part of the glue will stay fixed on bezel, now forming a “holder”, like handles on a pot. These 2 hardened Elmer spots will work for other film that you might want to try.
Used this on my monster lights (15000+ lm) and no problem with heat melting glue, so far. The hold as mentioned very secure.
