Yellow Headed Blackbird

[Aloicious]

Was out giving the 600+1.7x a good testing out at the bird refuge, got some okay shots...I gotta say I'm kindof disappointed in the 1.7x's AF performance, there were ALOT of shots I came back with that should have worked, but missed focus, unfortunately I just think making the lens a f6.7 wide open is a bit too slow to maintain AF quality with some of these faster birds. I think I need to grab a 1.4x at some point...the 1.7x works good with a F2.8 lenses, but not so much with an F4, oh well.

 

[ceeboy14]

The top shot is pretty sharp but agree the bottom one is quite soft. Is it possible the sweet spot for the lens isn't at 6.7 or there is a front or rear focus issue with the lens? I got the 1.7 for my 70-200 on the advice of a lot of sports photographers who noted the 2.0 had issues. It will be awhile before I get a longer lens, so cannot attest to the accuracy of this statment but I do get pretty sharp images with the 1.7.

 

[Aloicious]

yeah, the 1.7 works great with the 300 2.8, but with the 600 being F4, I think its just a little too slow for reliable AF performance, I had alot of AF hunting, etc. I didn't expect it to match the performance of the bare lens, but I was just a little dissapointed in how it ended up, the few shots that came out were pretty good, I've actually calibrated the AF fine tune, so I don't think that's the issue with it...I really just think its a little too slow being f6.7 wide open. with a 1.4x I'll be able to get f5.6 and even stop down to f7.1 or f8 or something....

I was out shooting and thought I got some excellent shots, but when I got home and was reviewing them, like 75% of them missed focus, just kindof a bummer. oh well, my next days off are supposed to be good weather so I'll go out w/o the 1.7 to the same area and see what I can get.