I finally got out today for the first time this season thanks to a friend visiting from Atlanta that wanted some shooting company. My Mk2N is in the shop for Error99 problems, so this one was captured with my back-up body (40d). I'm not normally a fan of white sky backgrounds, but this may be the first one I've gotten that works for me. Captured at the Alligator Farm rookery, Canon 40d, 100-400L IS lens 1/3200 at f5.6, natural light, +2/3EV, full frame (not cropped). Processing: minor shadow/highlight and constrast adjustment.
A remarkable display of translucence, esp. the tail. Sharp, nice stick, great wing and tail spread.
The bird is angling a little away. I might suggest you add some canvas at the top, and I might crop just a bit from the left, or add more canvas on the right to decenter the bird a bit more.