I've got a bunch of Streamlight ProPolymer 4xAA general purpose lights strewn around the house. I like the form factor (easy to slip into a back pocket) and the use of AA batteries. Problem is, these lights are throwers with an intense hotspot. For some time now, I've been looking for a film that I can apply to the inside of the lens that will spread out the hotspot a bit. I picked some up off CPF Marketplace which diffused too much, completely obliterating the hotspot and turning the light into a pure flood. Also on CPF, I saw a recommendation for some (Fellowes) WriteRight PDA/phone screen protector film. I must have gotten the wrong one because the ones I've have are absolutely clear with no diffusion. Also tried following up on a particular lighting diffuser used in photography, but couldn't find it anywhere. So. Anyone have any ideas for an adhesive film that will give just a slight beam diffusion?
There are companies producing (non-adhesive) diffusing film and colored films for the lighting and photography industry. I got some samples from GAMproducts, they're diffuser films are made for filming and stage lightings (not only for this purpose) and able to withstand some heat. The films come in different strengths of diffusion, unfortunately it is hard to tell from the distance which strength you need. Of course there is also LEE (well known by photographers) and 3M. The latter produces a lot of adhesive tapes, maybe they got some nice adhesive diffuser foil too ?
+1 on LEE gels.. I've been using heir stuff for years, mostly when I did studio photography.. Chances are, you can find a pro photo supply store locally and they will have a large selection of filters/gels. Here in San Francisco, we have JCXexpendables.. They sell 12x12 (or larger) for <$5 or so each (some are more depending)
The problem I have with the photographic stuff is that a) Since I don't know which filter I need, I have to go look at some... and b) The camera shops in my area are not particularly well-stocked (at least the sales people knew what I was after, they just didn't have it.)
Check GAMFusion on the GAMproducts page, they describe the grade of their films. Tell me the number which come the closest to your needs and I'll check my samples and tell you if the result meets their specs in reality. (I could provide photos too, but this is a bit more work and it's already 11pm in this part of the world.)
Try and get a LEE filter swatch book or Roscolux swatch book from a photo or theater supply. Some of the online places will throw one in for a buck with other orders. If you are lucky you can just get someone to send one out. Anyway, these are several inches thick and around 1.5x3 and cover every scrim, diffuser, gel, etc the companies make. More than an adequate size for flashlights and normally for photo flashes (I'd cut them off, put some little gaffer tape tabs on the end and then slip those tabs under a ranger band on my flash). If be careful about applying inside, though. While these things are heat rated they really do want some air between them and the source and you may find you've melted something permanently in place.
Just to make this clear, GAM is a ROSCO division and I got one of these swatch books full of samples. You could order them in the past for free, but the company stopped that, because strobists and light painters discovered this and ordered a few.
Yea that was going to be my recommendation. Layer if needed. I just looked it up and adhesion seems to go away at 100 degrees Celsius but that's dang hot for non-Incans.
Hadn't thought about Scotch tape, have to give that a try. Thanks to all for the replies. I'll be sure to post a followup if I find something that works.
I would be reluctant to use scotch tape, as it might get gummy or discolored with heat. If you can't get your hands on photo/video gel diffusion film, you could also try parchment paper.
Although minimally-probable, hair spray has a propellant that can cause ignition. Stick-on films eventually fall off as the adhesive dries. Photographic film is expensive and needs a way to attach it to the lens. Your best and least-costly bet is 600-800 grit sandpaper and a few minutes to just make the polymer lens slightly translucent.
Probability of ignition rises exponentially among males with every year of age under 16. Thanks, 0dBM. Yeah, I pretty much came to the same conclusion. Going to look around for some cheap replacement lenses (off to DX to see what they have). Thought about starting with polishing compound rather than sandpaper, though.
A much older thread on EDCF suggested using 3M micropore tape. http://edcforums.com/threads/flashlight-diffuser.81242/ Has pictures, but no beamshots.
