Theoretical question. The D800 has an insane sensor that can capture a huge amount of information in FX mode. When used in DX mode it can also capture a large amount of information (more than the D700). My question: if you know from the outset that the lens you are using isn't long enough to capture what you desire, is it better to shoot in FX mode and then crop or shoot in DX mode? Shooting in DX mode should put *most* lenses closer to their "sweet spot" regarding MTF curves. But not sure if there are other factors that need to be considered (and also acknowledging that MTF curves aren't everything when using a given lens). This is really an academic question on my part: the D800 is the first body that pushes FX into the medium format category (at least regarding file size) and can at the same time capture DX images that are large enough to tolerate significant cropping and manipulation when needed. So FX and crop or shoot in DX?