When I got out of the army in 1947, Panatomic X was ASA 25, Plus X was 50, Super XX was 100, and Tri X was yet to come. These were ASA ratings, which everybody said were too slow. Sometime in the 50's Ansco came out with Super Hypan and box speeds doubled all around. Super Hypan IIRC was 500. I think it came out before Tri-X. The fastest film I used was called 2475 Recording film. With it I got some pretty good photos of my son's rock group at Joe's Fish Market in Virginia Beach. That was in the 70's. Why can't I remember what I used yesterday?