I just purchased a D7100 as an addition to my D800 for the times when I am using a telephoto to catch closeups of smaller objects, i.e., not for landscapes. I reasoned that the D7100 is giving me 24 MP while, in comparison, the D800 in DX mode is giving me 15 MP. However, I see no value to the 1.3X crop mode of the D7100 except to have smaller files. The fact is that 1.3x crop mode simply crops the DX sensor before taking the photo as opposed to cropping a DX image in post-processing with an editor. Again, other than saving space on your memory card by 'pre-cropping', it buys you nothing.