5D Mark III weather (at Ridgefield, Wa.) for sure (as opposed to the 7D Mark II), on this overcast and showery December 6, 2015. The 5D excels in noise control over the crop sensor body at elevated ISO settings. Not my personal favorite own shot of the Bufflehead but I like how the iridescent colors emerge and somewhat brighten the drab gray tone of the image.
Canon 5D Mark III, 1/1250, f4.5, ISO 2000, 500mm, 1:49 p.m.