Quote Originally Posted by Johnny Rasmussen
I have never heard that underexposure will give youless noise. I thought it was the opposite.

You are correct for all the other ISO settings. 200 has less noise than 100 -1 EC. 400 has less noise than 200 -1 EC and 100 -2 EC, so on and so forth.


But when you get to ISO 3200 it changes. ISO 3200 has the same noise as ISO 1600 -1 EC. But since 3200 throws away one full stop of highlights (1 stop less DR), it is bad.


Quote Originally Posted by Johnny Rasmussen
I have sometimes set my camera to -2EV at ISO1600 simply because I needed the shutter speed. But the images needed a lot of work to become usable.

ISO 1600 with -2EV is the exact same as using an ISO 6400 setting, if your camera had one. The only difference is that ISO 6400 would throw away 2 stops of highlights for no reason, so 1600 is superior.


Canon did really great with most of their ISO settings, but some of them were horribly botched.