D-c-fix diffusion film

http://shop.leefiltersusa.com/Swatch-Book-Designers-Edition-SWB.htm

For heat concerns, Lee makes a Zircon line that is heat resistant:

The 802 Zircon Minus Green reduces lumens by 25, that would be closest to the 1/2 minus Green, that reduces by 28

the following percent numbers are the amount of light transmitted, so 71.5% transmission means 28.5% lumen reduction…

Lee 248 Half minus green: 71.5%
Zircon 802: 75%

Zircon 803: 79.9%
Lee 249 -Quarter minus green : 81.5%

Zircon 804: 83.6%

Zircon 805: 86.6%
Lee 279 -Eighth minus green : 87.2%

Discussed here

Examples of with and without Lee

Thanks for the explanation.

So, output is cut ~10% but intensity is cut ~30%.

Those are just examples from one light. A BLF GT will probably suffer a lot more of a reduction in intensity.

So, a floody light will lose less intensity than a thrower? Is it a logarithmic effect?

I haven’t done the math or the measurements so this is just a guess, but it might just be a function of lens size. Bigger lens = more diffusion film = more diffusion.

Just an educated guess. If you already have a somewhat diffused light (eg small heavy OP reflector or frosted optics), naturally adding more diffusion doesn’t have the same impact as diffusing a very narrow beam (large SMO reflector).

That makes perfect sense. Thanks!

Okay, here’s a thought. It would be nice if someone would test this hypothesis. Compare a small, but throwy light (such as Convoy C8), to a larger, floodier light (such as BLF Q8), both with diffusion film. I’d love to see measured results. :wink:

Doesn’t sound right. It seems to me that
Bigger lens = less light hitting any spot = just like lower mode = no effect on diffusion.
Though when pattern size is large in relation to lens size that would be different.

I made this…not the best…but u kinda get the idea.

That’s probably a better guess than mine.

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.

This looks like a good answer:

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.

Mine too, but we were talking about intensity, not flux.

I have a modded Convoy C8 that is essentially a Sofirn C8A . With the DC Fix it is like a C8F beam on medium.

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.

received fast, ordered from : https://www.ebay.co.uk/itm/d-c-fix-Klebefolie-Selbstklebefolie-Möbelfolie-Fensterfolie-Dekor-Folie-45-cm/123186082615?ssPageName=STRK%3AMEBIDX%3AIT&var=423594199712&\_trksid=p2057872.m2749.l2649

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.