I took this picture today – through my kitchen window, from about 30 yards out. If you look closely, you can see a cardinal in one of the trees.
I uploaded it to some photo editing software that I downloaded from the net (Faststone Image Viewer), and zoomed in on the bird. The first attempt came in like this:
Thinking I could maybe get even closer, I zoomed in again. The final picture looks like this:
If I make it any larger, I loose a lot of clarity. Even so, for a shot taken through a window, I think it came out pretty good.