I picked up my Nikon D4s at the weekend after being strong and not heading for the camera store when they called me on Thursday. Took it out for a test drive attached to my 800mm to photograph hummingbirds (most shots where taken with the TC 1.25 converter attached). Although this lens gives you lots of working distance, the problem is the minimum focus distance, and finding the hummingbird with the small angle of view (something that you get used to). Conditions where overcast in the morning, brightening up in the afternoon (although the breeze kicked up which meant the birds where swinging to and fro on branches). The attached photo of a Rufous Hummingbird (Selasphorus rufus) was shot at ISO6400, 1000mm, f8 at 1/1250sec , which was the ISO I shot with for most of the morning. The image is straight out of the camera (with sharpening applied when I exported the jpeg). I like what I see so far.

Rufous Hummingbird (Selasphorus rufus)