If you set extended ISO via the custom function, you’re able to select it quickly using the main dial.
Does anybody know if, when you have extended iso enabled all the time, this affects the quality of the native iso settings?
So, is there a difference in IQ performance when extended iso is activated, but not selected?
Canon's line on this is that there is no impact. The only reason for the CF is to prevent accidental selection of H or L, which when used will produce an image with considerbly less dynamic range than one taken with native ISO settings.
