Quote Originally Posted by ricardo12458 View Post
It might not really matter, since I'm taking a long exposure with it.

The only reason I would use this film would be for astronomical photography, especially for something this old, to get over the base fog.

I don't develop my own film.
Film is much better since 2475 days. I believe 2475, like other out-of-date high speed films, would have lots of base fog. The 2475 recommended exposure time for metered 1 second exposure is 1.6; for 10 seconds, 25, for 100 seconds, 500. It was even worse for the standard films of that day. A 1998 Kodak publication gives the increase for T-Max 100 as: 1 second, open aperture 1/3 stop; 10 seconds, 15; 100 seconds, 200. For T-Max 400: 1 second, open aperture 1/3 stopt; 10 seconds, 15; 100 seconds, 300. For T-Max 3200: 1 second, none; 10 second, 15; 100 second, 400. Even fresh 2475 would have little advantage over T-Max films in reducing expsoure times, and a great increase in grain.

If I shot any 2475 that might be mislaid in all my junk, it might be to develop it in print developer for high contrast and gross grain, and reduce the negatives in potassium ferrocyanide to cut through some of the fog. Such post development reduction might be controlled better than using Benzotriazole with the developer