I still have Kodachrome ASA 10 slides I made in 1952 with my PX special Argus C3. When Kodak changed Kodachrome from ASA 10 to 25, a lot of pros bought up all the old ASA 10 they could find and put it in the freezer. I did the same later when they stopped making ASA 25. Don't remember now what Big Yellow thought was "better".