I looked at the 50-500 but just didn't see myself lugging that thing around, it is huge. I have a friend that has one and I've used it several times and have been happy with the results although it gets a little soft at 500. I also looked at the Sigma 120-400 which is a little smaller, cheaper and comes with the optical stabilization (Sigma's version of VR
) . I think this one gets pretty good reviews all around.
In the end I got the Sigma 70-200 2.8 as well as a 1.4X teleconverter. I've been pretty happy with it and and have manged to get my first photos into the DB
after trying with my Nikon 70-300 cheapy for a while. If I had a few more bucks I would have gotten the Sigma 100-300 F4 ($1300ish).
I have shot quite a bit with the Nikon 80-200 and to my eye the quality is the same as the Sigma 70-200 (at least my version).
In the end alot depends on how much focal length you need. I have found from where I shoot 300mm is about as far as I need so the 70-200 with the 1.4x teleconverter is what i have on the camera almost all the time. If you need 400-500 then you'll need to go to something else.
While shopping I gave alot of weight to the F2
.8 on the 70-200 but in reality I almost never use the lens below F5.6 so in hind sight it probably isn't a huge factor.