I just bought this camera used today (and I can return it if it's not working properly.) I put a roll of Tri-X 400 in and snapped away downtown. Unfortunately most of the photos are under-exposed. Here are 2 samples ... This photo came out under-exposed: Yet this one seems quite OK: I set the ISO on 400 - is that wrong? Am I metering incorrectly? Is the camera busted? (In which case I'll promptly return in tomorrow ...) Ken Rockwell (here) says: Is this advice I need to follow or can I ignore it?