Went down to Carter Creek with my long glass and tube early this morning: Nikkor 300mm + 52.5mm Nikon PN-11 tube. Had forgotten that I left the WB on incandescent and had to correct on PP. One of these days, I'm gonna remember to check every setting before starting.
Shooting specs: Early morning light, Nikon D300(aperture priority @ f/5.6), Nikkor 300mm on 52.5mm extension on tripod w/cable release.
Excellent set with great light. I find focusing the hardest part with long lenses as well, I'll often find that I just missed the eyes even though it looked spot on in the viewfinder. I seem to manage to accidentally alter the dioptre adjustment on the viewfinder sometimes as well, which doesn't help