Quote Originally Posted by TOM View Post
i am only guessing here, but i suspect that the catalyst for most people's desires to upgrade their camera, is better ISO performance, when the most logical step would be to upgrade to faster, better glass.
Obviously, a lot of this depends on what you are photographing, but better glass introduces DOF complications - another current thread is talking about using a 200mm f/2 lens for indoor events, but wide open, the DOF is too thin. (I also think that better technique and more care fixes more sharpness issues than either a new lens or a new camera.) Finance is also an issue - in some cases, you get more "bang for the buck" out of a new body vs a new lens.

BTW, as I have posted elsewhere, my own desire for an upgrade was more related to AF and body issues rather than ISO (and I've yet to really outshoot my existing lenses )).