How is ISO determined?

[Jon Ruyle]

on the 5D2, 6400 is a 'native' ISO, but it is based on digital gain (3200 is the highest analog-only gain).

Really? I was told 1600 was the highest.

If 3200 is the highest analog-only gain, then what do you mean when you say 6400 is 'native'? Do you simply mean it is not an expanded iso?

[Daniel Browning]

If 3200 is the highest analog-only gain, then what do you mean when you say 6400 is 'native'? Do you simply mean it is not an expanded iso?

Yes, that's what I meant.