Purple Finch 2

I like the pose and light Claude. It looks like you had accurate focus on the subject. The detail on the bird in the larger version, although not stellar, is good enough to make this work for me.

Cute pose. Sharpness is better on this, but still not quite tack sharp on the bird. It almost looks like the selected AF point was on the stump (especially in the larger version)

Thanks, I checked the camera AF fine tune with the TC 1.7X on the 600mm, seems like the TC caused AF fronting. I corrected and will test in the field. Correction is +10 on the AF fine tune.

I'm assuming the 'new toy' is your camera body Claude?
Solid image, good to hear you've worked out the AF 'fronting' issue.

Claude, I have done quite a bit of testing with this same setup. I find that I can almost always get sharper images by using NO teleconverter. Even the 1.4x seems to have a detrimental effect. Try using just the D800 and the 600mm. You might be surprised at the difference in results. Nice bird and pose, good sidelighting. Still, a bit soft.

Claude,

A very nice looking bird, sharpness problems are in my opinion all to commonplace using convertors, even with Canon

I just simply figure that adding a $500 convertor to a $5,000 lens just cannot be that great.

Nice colours and nice pose Claude. BG also works well.
To my eye the bird itself is not as sharp as it could be.
Shooting at 1/800 with a 1020mm lens could be the issue here. Try without the TC. Even though you won't get so close, you'll have sharper images which lend themselves better to cropping.