I've got the 100-400L IS and have never been able to get a tack sharp picture with it since I bought it in December (Using the Canon 20D). I had to send it back once already as it started hanging up when I'd zoom with it at around 200mm. I've blamed myself for the crappy pictures, presuming I was shooting to slow, or not sure about the Photoshop hardware for sharpening, noise, etc. Finally after another dissapointing weekend, I went to San Carlos Airport last weekend and shot about 150 pictures of planes taking off in every speed and configuration of settings that I could use. Not one of them was crisp, even shooting up to speeds of (TV) 1000. This included a few jets from SFO.
I've gotten nice results from my smaller lens on air to airs, but nothing good from the big lens. After a lengthy talk with Canon about my issues, they want me to send in both the lens and body. This really sucks as I've got an air to air session this weekend, if the weather holds out, and more for the following two weekends. Looks like it's back to film 'till I get my setup back

_________________
Roger Cain
www.sfahistory.org
http://groups.yahoo.com/group/Stearman/
We must limit politicians to two terms:
one in office and one in jail.