Scalesusa, thanks for your information, and I think those are very helpful. when I use my 300mm 2.8 to shoot birds, the shutter speeds were almost always faster then 1/1000, in fact, most of the times they were faster then 1/2500, so I guess I can just save $2000 for not getting that IS function.


Brendan, thank you for your reply. I think we both love bird photography, I especially like to shoot BIF. the 300mm is really a nice lens but a little short(though perfect for larger birds in flight like pelican) and a little heavier for handholding(at least to me), so I'v been thinking getting a 600mm, $3000-4000 is a lot of money, and I have never bought a used lens, so I'm still thinking about it. BTW,I'v noticed that your bird shots were getting better and better I'm waiting to see your more bird shots.