Found 2 rolls of this very obscure film, expired in 1973. Its original application was CRT photography, missile tracking and spark-chamber photography.
Found this datasheet about it:
According to it, at gamma 0.7 it had an original speed of 800. Very fast for the time!
It is VERY grainy though, and has lost a lot of speed since due to increased fog. I would probably rate it EI25 were I to shoot more of it. According to the old rule of thumb one stop per decade, that is 5 stops. So 800-400-200-100-50-25. Yup, about right.
I developed it in XTOL 1+1 for 9, 11 and 15min and it was pretty difficult to get good looking negatives. The contrast was too low at 9, 11 was better but increased fog, and the fog at 15min was so bad that it actually lowered the effective film speed. As I’ve stated before, for expired film you want to use a short development time.
I did a couple of densitometry tests and here are the curves for 11 and 15min of development. They are a bit wonky because I did not expect the film to be so slow and the fogging got pretty bad at 15min so I’m not sure what is going on with that hump at the toe. I increased the exposure for the 15min test so that also causes the scale of the entire thing to shift.. yeah, good enough, and I ran out of film to test with. I think this film was originally pretty low contrast with lots of potential for push processing, kind of Delta 3200 is today. It was probably difficult to overexpose to the point where you can’t recover any detail, which would make sense considering it’s original application.
Would I buy more of this stuff if I found any? No, I wouldn’t. But it’s always fun to experiment with stuff! Here are some sample images.
