Messing around with some favourite Rollei Blackbird this week led to a rather unpleasant surprise. I know there’s speculation on various sites that it’s an orthochromatic film, but I’d never done any testing as I just liked the results. If you’ve ever used it you’ll know it produces dark, moody results unlike most modern film.
If it is true orthochromatic film it ‘has too high sensitivity to blue, generally correct sensitivity to green and bright yellow, but has too low sensitivity to orange and is practically insensitive to red’ (a quite from the above link).
Forgetting the ‘ortho’ nature of the film I shot a few frames with a red R25 filter and what resulted was – absolutely nothing. A completely empty frame. I haven’t found any detailed data on how sensitive this film is to different colours so I thought I’d better do a quick test…..
Apart from the much higher contrast, it’s obvious that the film isn’t sensitive to red or orange. greens look fine and blue seems a little lighter – so just as per the definition.
Developed in ID11, 10 minutes at 20 degrees centigrade, scanned with a neutral profile.
If you already know this was an ortho film, here’s the proof (which you didn’t need), if you didn’t know (or you’ve forgotten as I did) this info should prove useful when using it (without a red R25 filter!).
Thanks for looking!