Quote Originally Posted by DavidEccleston View Post
I think the price would exceed the 70-200mm f/2.8L IS II that I'm trying to avoid buying.
I knew if you worked the thought process long enough you would stop avoiding the right answer. I know from experience the 70-200mm II will do the job.

Denise did have the right idea though, primes will rule over the zooms for the fast moving little doggies. The primes just to fast and accurate, where the zooms are less so and the AF point varies over the range. You are not going to match the sharpness either. A thing I always weigh when choosing one over the other, will the truly great shots out of the prime make up for the good shots I miss because I do not have a zoom.