this shot of two pileated woodpeckers working on a nesting tree was taken with a Canon 7D Mk II at ISO 6400, 1/160 @ f/8.using a Tamron 150-600mm lens at 400mm. the image was fairly noisy - at least by my standards - but cleaned up acceptably well for non-critical uses. i wouldn't make large prints from it, certainly, but it would probably make a reasonably decent 5x7 or even 8x10. obviously, the 7DII's low-light performance isn't going to threaten the likes of the Nikon D4s, but it's still pretty decent. i'll be interested to try it in low light with a wider lens, like my 24-105, just to see if that makes a difference... long telephoto zooms aren't the best choices for high-ISO shooting!