(if you did not receive a message from me, please don't feel bad, I've received a good # of PM's regarding this sale, too much time to individually reply to each)
you'll technically be exposing it "normally", you're just cutting down the light down if you want to slow your shutter speed as if exposing for the shutter speed(1 more stop over a 100asa film) req'd by a 50asa film.
Shoot Ektar 100, or use the Gold 100, its good stuff too, not as fine grained, but I've used it @ ASA64, and the reds/yellows(warmer colors) POPPED. Like E100VS poppy.