Giraffes at Twilight, Linyanti Swamp, Botswana
It was past sunset and actually much darker than it appears when I took this photo of two giraffes in Botswana. I upped the ISO to 3200 and opened up the aperture to its widest setting in order to avoid any motion blur on the slowly moving giraffes — while still adding quite a bit of light to the scene.
Nikon D700 with Nikkor 70-200mm lens (at 75mm) ISO 3200, f/2.8 at 1/250th of a second