Originally posted by tux08902 What is the obsession with FF? I don't understand it. I realize that lenses have gotten narrower in their FOV, but that only means that we need lenses with smaller focal lengths to offset that. Really, that's all it is. In addition, FF technically means larger lenses, which I'm not in favor of. Yes, I like a big camera, but I don't like lenses that look like airplane jets and feel like them too! I think the 645 D option seems like a nice option for people looking for something like FF.
With technology and physics as it is today, FF addresses some very specific needs of some photographers, mainly, better high ISO performance, dynamic range, greater control over DOF (for those who favor really shallow DOFs), and the possibility for greater resolution.
I'm a mere hobbyist, so those items don't apply to me (perfectly happy with APS-C), but I would understand other hobbyists and working pros who would want those.
High ISO for concert shooters and sports/action photographers. Manufacturers can continue to eke out better performance in APS-C sensors by minimizing circuitry in the sensor itself (like what Olympus and Pentax/Samsung did), but that same workaround can also be applied to FF sensors and even gain better high ISO performance.
As for DOF, a 1.2 aperture lens mounted on FF can deliver shallow DOF that cannot be matched by APS-C. That may make for some more creative shots.
With regards to resolution, I'm perfectly happy with 10 MP, really, but there are those who need to print bigger (ad photographers), or would want to show more detail (fashion and landscape photographers). As well, having bigger MP counts can allow for greater cropping (something I don't do, but would benefit others).
As for the weight and size penalty, it's an acceptable drawback for those who have need of FF cameras. It's certainly not for all, though, so I think APS-C will still be there co-existing with FF.
I won't need it, but I certainly won't complain also if Pentax chooses to develop a camera system with a FF or 645 sensor. Just because I have no need for it doesn't mean camera manufacturers have to stop making those bigger-format DSLRs altogether. Different strokes for different folks.