I've had alot of fun with the new canon70-200ISf4, a improved f4 with image stabilization.
I wanted a lighter weight lens with the use of a teleconverter, trying to get 300mm to 400. The 1.4x is better focus ability and clarity. But I thought I'd give the 2x @ 400mm. Handy to have with me, but the 2x is iffy on focus, so for bird flight, I wouldn't recommend chancing it with the 2x, unless the target is stationary. The 1.4x is a higher percentage shot, but at 280mm sometimes thats just not enough length.
But these turned out excellent for a zoom +2x. The lens is wonderful btw. I hand hold, so IS is a biggy for me. [these were taken in Irvine yesterday]
I believe a Sharp Shinned Hawk
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