Flashgun, IR Filter, and What Film?

[amuderick]

I'd like to do some Weegee-style IR photography at night or in darkened parties, etc. I have a potato masher with a guide number of around 160. If I affix a Lee 87 gel in front of the flash, what kind of aperture/distance do I end up with using any of the IR films from Rollei or Efke?

I know that sensitivity of these films is far less than HIE in terms of depth into the IR and also in terms of ISO at IR wavelengths. But, with an IR light source, is the effective ISO stuck in the 1-10 range (as quoted in other threads)? That isn't going to get me much distance from the subject unless I really stack up the flashes and/or dive into IR-coated flashbulbs.

I know that I'll need to experiment to find the right exposure for my equipment. However, I'm looking to you for ballpark figures that this isn't a dead end before I spend some money on filters and film.

FYI, I'm not looking for an IR effect, per se. I just want the flash to be as 'invisible' as possible.

Thanks!

 

[AgX]

Type Wratten 87 is quite strong for these films. However, the next types, 88A and 89B are said in literature to let pass a bit of visible radiation. But perhaps you'll give them a try.