Quote Originally Posted by cowanw View Post
Also, if using flash, the ISO need not be set at 1600 because of low light situation. You are providing a high light situation with the flash. using your post #3 hypothetical you could easily use ISO 100
+1

The only reason to use ISO 1600 is if that is the film you have. If you are choosing a film for use with flash, I'd recommend a slower film.