Since buying a used 1DmkIII the light here has been nothing short of missing. But this gave me chance to test the higher ISO capabilities of the 1D. When using the 7D I dread having to go as high as 800ISO, so it was with trepidation that I set the 1D to 1600ISO. But the results speak for themselves.
800ISO is good. I holds colour, even in the blacker areas but noise is not there.
1600ISO starts to show noise but there are non of the ugly red splodges I get with the 7D. Saturation is lower but somehow natural. Easy to boost in PP.