Originally Posted by Chewy734
Good question Dave. My only guess is that it's easier to AF at a far away point in crop mode than on FF, where the point appears even farther away. At least that's the only thing I could come up with.
I've got a FF body and a 1.6 crop body. I primary advantage of the crop body is that small moving subjects are larger in the viewfinder; however, I get the idea that the viewfinder will be unchanged and the image file will simply be digitally cropped. Unless I get an improved viewfinder view, I'd just as soon crop the image myself as part of RAW conversion.
I think this feature is mainly for video, where downsizing could be critical to save CF card space.