Infrared Film Exposure Question

2F/2F said:

Steve, Rollei IR400 with a 25A filter doesn't look much different than any other panchromatic film with a 25A filter. It is an expensive film (10 bucks a roll last I shot it). I wouldn't bother using it unless it is with heavier filters than a 25A. It is not unique unless you use it with an opaque filter, or a near-opaque one like the R72. Without a heavy filter, it might as well be T-Max in the camera, IMO.

HIE, on the other hand, definitely looked like an IR film when used with a 25 or 29 see-through filter. That was HIE's greatest strong point IMO: it could be used hand held with IR-looking results, and without having to shift focus.

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I agree. I would have to get a stronger filter and the cost of the film ... excuses ... but I would rather work with my 4x5s and learn large format in more depth, use the Hasselblads for my serious [sirius] work, and 35mm for traveling light when I what I am doing is not centered around photography than shoot IR. There are too many other interesting things to do.

Steve

2F/2F said:

Steve, Rollei IR400 with a 25A filter doesn't look much different than any other panchromatic film with a 25A filter. It is an expensive film (10 bucks a roll last I shot it). I wouldn't bother using it unless it is with heavier filters than a 25A. It is not unique unless you use it with an opaque filter, or a near-opaque one like the R72. Without a heavy filter, it might as well be T-Max in the camera, IMO.

HIE, on the other hand, definitely looked like an IR film when used with a 25 or 29 see-through filter. That was HIE's greatest strong point IMO: it could be used hand held with IR-looking results, and without having to shift focus.

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This jibes with my experience with the Rollei material. Somewhere I saw a graph of the HIE spectral sensitivity that showed it not only sensitive way farther into the IR spectrum, but also what looked to be a bit of a notch in the yellow green range. Thinking area-under-the-curve stuff I'd guess almost any red filter would skew HIE pretty well towards IR. The Rollei barely makes it into the IR range; I somewhat preferred the effect with a 760 filter over a 720, but that involves working so far down the spectral cut-off it takes a lot of extra exposure and seems a bit touchy for latitude.

Enh, experiment, experiment. And as pointed out, though the Rollei 400 is a nice pan film, the price of a roll would buy about three of Acros 100!

In my experience with infrared films using a Hoya R72 filter, I always meter the visible light and focus, apply the filter, adjust to IR focusing marked on the lens and adjust / bracket +4 to 6 stops. Never had a problem with any infrared film and the results are amazing! As far as ASA/ISO goes, I either follow the retailer's suggestion or set it at 200. I heard with these new IR films in the market today, a Red 25 filter is impracticable but I have never tried it for myself. I am a big fan of EFKE IR820 Aura because it's the closet film to Kodak HIE (R.I.P.).