Sharpness and long lens technique.

    I was reading a recent blog from Moose Peterson (one photographer that I look up to) regarding sharpness and have always struggled a little, as I am sure most have, with getting really sharp shots when using a super telephoto lens.  In my case, the Nikon 600mm f/4G VR lens when it is used in conjunction with a teleconverter.  I have practiced the proper long lens technique that Moose describes here as much as I can. 

    When I have the 600mm VR on naked (no teleconverter) I can get very clean, sharp shots.  Once I throw on a TC, the whole game changes for me.  I try to keep the shutter speed at least the same as the focal length that I am using, which would be at least 1/640 for 600mm and so on.  This does not always work for me as I tend to get shots that are less than sharp and sometimes I have to crank the ISO up to get the shutter speed where I want it at the aperture I set (I tend to use aperture priority on my Nikon D3s) which gives me more noise than I care for when it is first light or last light.  I know it is not the tc as I have gotten razor sharp shots with the Nikon 400mm VR of birds in flight.  I suppose I just have to keep practicing.  What do you all do? I am quite curious to see if others are in my situation or if I just doing it all wrong.....

Here are a few shots with the Nikon 400mm f/2.8 VR with a Nikon TC-17e II teleconverter:

Nikon 400mm f/2.8 VR with the Nikon TC-17e II

Nikon 400mm f/2.8 VR with the Nikon TC-17e II