I recently purchased a Nikon 500mmF4 VR and I took it out for a test run last weekend to Cape St.Mary's. This is an image I have had in mind for a few years now. With out the reach of the new lens with 1.4x teleconvertor at 700mmm this image wouldnt have been possible.
Nikon D7100, 500mmF4, F7.1, 1/640s, ISO400, Tele 1.4x, 700mm
I have seen images like this before and I still like them... This is very nice, its sharp although you could do with a bit more selectively at the tip of the beaks.. My main suggestion/thought is to rotate the image CCW slightly so the symmetry of the two bird is about the vertical axis. Seems trivial but I think it would help..
It looks like you're making good use of your new lens. Wish the second head was just a little more turned, then the image would be perfectly symmetric.