Harry Lime, I would be keen to know how your experiment goes with the IR flash. I am improvising a similar system using a Nikon EM camera set on the manual shutter speed of 1/90. Mounted on this is a Vivitar 283 flash unit covered with a 720nm filter. This will be for photographing wildlife at night at some distance. I will have to do a test run when I have adapted the flash unit. I did try Efke IR820 film with a 760nm filter (on a weaker flash unit than the 283) and I captured virtually nothing. I think this was because the Efke is a slow film, even if it is more receptive to IR at a higher frequency. I am hoping the faster Rollei film might produce better results.
Lowlight, the Rollei isn't really much faster than the Efke.
The issue is the spectral sensitivity of these films. If you look at the curves, the sensitivity drops off very rapidly in the near IR.
To play the IR flash game, you really would want some fresh HIE or... a (sorry, sorry) digital camera with the hot mirror removed:
I have one of these unmentionables and can actually make IR movies of it with a deep IR filter. I do wish HIE were still around....
N.b. it may be possible to boost the IR sensitivity of the Efke or Rollei by treating it with some sensitizer or by hypering it. Ron could advise.
You need IR illuminator, not IR flash.
Thanks keithwms and georg16nik. I would really like HIE to still be around too. You see it on ebay now and again, but course expired. You can even buy old Kodak Aerochrome 1443 on ebay but not sure how far into IR realm that film goes. I have a good IR illuminator to boost the range on my Sony nightshot camcorder, but I definitely want to try IR flash with film. I did consider breaking open my Finepix S6500fd and removing the hot mirror but would probably wreck it if I tried, or fail to put it back together properly. I don't want to pay much, so ideally want to use the 35mm film photographic equipment I already have. Using a 720nm filter on a powerful flash unit like the Vivitar 283 should give me a window of some 40nm in spectral sensitivity (720nm filter with film sensitive up to approx 760nm=40nm). It's not a big margin to play with but theoretically it should produce something the film can capture. Still, I'm tempted to buy the next decent looking roll of HIE that comes up on ebay.
surveillance specs IR illuminators goes up to 950nm, usually have an optional image intensifier tube, could lit quarter mile distances with ease.
Zeiss used to manufacture such toys and these days could be found second hand for reasonable prices.
Films like Rollei ir400 (Agfa) or Efke ir820 were designed around such IR illuminators