In article <47825o$hck@mail.one.net>, spaceboy@one.net says...
(About simulating 12,000 ASA on a camera with a 6400 maximum setting.)
>Simple enough. Set you camera to 6400 and use what ever shutter >speed you want. What ever f-stop is recommended open up one stop >past that. Example if you selected a shutter speed of 1/4 and your >meter recommended f-5.6 open up one stop to f-4.

Methinks you mean stop-down one stop, or use one shutter speed higher
than indicated.... (to give less light to the film, which is what faster film requires for correct exposure relative to slower film).
Though, I must admit to having never seen a film that could be correctly exposed anywhere near 12k ASA!
Hope this helps.