About two years ago there was an option to adjust the ISO lower than 100. I don't remember the different values but one was Canon ISO and the other was DIGIC.... maybe... but that doesn't make sense because Digic is Canon... either way, I don't remember the options but it was possible. I messaged a1ex in the past because I was using it wrong and he told me it was for specific situations. I ended up have a green image. It was bad, and is probably why it was removed.