jason has given me permission to copy his text byb means back yard birds!
the pictures on nikon cafe back up what he says.
600VR, 2x TC (VII) BYB bird tests
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Been playing around with the "old" 2x TC VII that my good buddy Tim O. let me play with. I have used it a few times in the past but wanted to try it on small subjects that move around alot. Yesterday, I had about an hour or so to kill so I went out into the yard and got some test shots in.
Folks...for all the talk trashing this verison of the 2x TC, I just don't understand it. I am not one that believes in huge sample variation, but I guess that could be a factor. Anyway...I wanted to test this combo on close subjects as well as some farther away subjects where I had to crop in quite a bit. I also wanted to shoot stopped down as well as wide open. All the convential talk is the 2x is not sharp at all when shot wide open, folks...I am not one of those people. When I did my part on achieving proper LL Technique, the combo performed as it should.
The only negative I can offer or say, is that AF speed does take a hit on f/4 glass. However, it did not take me long to figure out a way to help this factor. It has been my experience, from testing, that if your set up, waiting for a subject to appear, and that subject could appear at several different distances, etc...it is best to focus on an object just outside the FARTHEST expected location. The combo will focus much quicker when reaquriing focus on subjects closer than it was previous focused at. If you go the other way is when you have issues with AF hunting. The elements will go in, then out...slowly and more often than not, you will miss the shot if the subject is moving. So with all the said, here are a few shots to show some results.
D300s, 600VR, 2x TC (v2), f/11, ISO 640, 1/800th SS, +.3EV, 60% crop