
Originally Posted by
NorthernFocus
In addition to what Joe mentioned, even if you never shoot at 2.8, the camera has a lot more light to work with(AF, auto WB, etc) as does your eye viewing the scene. Regardless of camera specs, the AF works better with more light. Also the DOF is flatter so the AF will simply be more accurate(assuming it is tuned properly). That's another one, you can tune AF much more accurately with flatter DOF.
At 300mm and down, f4 lenses provide a nice cost/benefit ratio. The Nikkor 70-200 f4 is one of my favorite lenses. I already owned a 70-200 f2.8 but bought the f4 for travel. Unless I'm planning on some really critical work I find myself grabbing the f4 over the 2.8 every time.