Thu 28-Feb-13 04:51 AM | edited Thu 28-Feb-13 05:02 AM by M_Jackson
llevine, I'd have several questions on this one. Did you take the time to check the AF fine tune with the combination before you went on your trip? Did "any" images come out sharp with the combination? Can you take your D4, 1.7 TC and 200-400 out in the front yard and get sharp shots (with and without the TC) at roughly the same distances? Did you get sharp images with the lens/TC with your previous camera?
There are lots of discussions on the Nikonians site about AF Fine Tune and even more in regards to adding a TC on a zoom lens. Check out the D800 forum for lots of discussion with people trying to get their D800 bodies sharp. Most of the discussions I read revolved around FoCal calibration systems.
Almost all of my lenses are zoom lenses. I never feel like my images are sharp with a TC, even a 1.4. With a zoom, you can fine tune it at one end of the zoom, but it might not be tuned all the way through to the other end.
If I were in your shoes, I'd try to start with the least amount of variables and see if I could isolate which part is causing the problems. I wouldn't add the TC in the mix until I knew the body and lens were focusing well. Somewhere on this forum, someone mentioned turning the CF down 10 FPS from 11 FPS in some situations.
Edit>>I re-read your original post. You said "some of your images are soft". I wish I could say ALL of my images are always sharp! With moving animals, reflections, swaying grass and so forth, maybe getting a few soft images is expected? On the blue heron, you focused on the gray feathers on the chest. I'd bet you would have had better focusing if you had shifted to the black and white details on the head and eyes. I get close shots of Cedar Wax Wings in June. If the focus point is on the chest, there is very little detail and contrast for the AF, but if I can move the point to their heads, it locks in.