The GAS is so bad today that I thought I needed to call a gastroenterologist! The pain started when I received my Canon evaluation loan today, a 300mm f/2.8L II. The attached x-rays, I mean pictures, summarize the pain. The image, in both full and cropped version, was shot right out of the shipping box on a 5d III with a 1.4x teleconverter. I have been looking hard at a 400mm f/2.8 II, but I do believe this prescription, I mean lens, may take care of my GAS for a while. A lot of money, probably more than it would cost to check out normal gas symptoms by the gastroenterologist. But, this lens will be a lot more fun than a colonoscopy, so well worth the $$.