There were a few of these guys inter-mixed with about two dozen surfbirds at Morro Bay today. This guy is pretty far into his spring molt to breeding plumage.
50D, 100-400 at 400
1/640, f/8, ISO 320
69% of full frame
Glad to see that you know it is 69% of original. Some insignificant person gave me a lot of grief over my precision at times with crop amounts.
Just curiously, do you crop the master file first before resizing and then compare the area (in pixels) to the area of the original? That is how I would do it, is why I am asking. Wonder if we agree or your method is different, yet works the same. :)