Thanks for the comments and welcomes, all. I think that the 300 2.8 IS is not bad at all on the autofocus side, but the image quality takes a huge hit when combined with the 2x II. CA, distortion, sharpness, and contrast are all fairly bad. Here's a 100% crop of the egret's head. There's barely any detail in the feathers, and this is absolutely as sharp as I can get the images before they look oversharpened but still not very sharp:


www.flickr.com/.../5455301413][img][View:http://farm6.static.flickr.com/5138/5455301413_6ebf947310_o.jpg][/img][/url]

Also, this was shot at f/8. The combo is best at f/11, but the 500 f/4L IS is even sharper at f/4, wide open.