The fast lens is a big part of it, but any decent photo editor can make up for some light weirdness...
Here's one of your originals of Walter
http://www.sonic.net/~claudel/20110407-2.jpg
Here, I balanced the light and shaded parts using iPhoto and sized it and adjusted the contrast and saturation with Graphic Converter...
http://www.sonic.net/~claudel/walter-iphoto.jpg
I didn't try to fix the eyes, but others have made some good suggestions for that.