Well, as I wait for my 50mm 1.4 to return from Canon due to a bizarre flare issue some of you may have read about, I now turn my attention toward the 15-85 lens. (I had recently sent it in for service due to rather poor corner sharpness, noticeable even when the lens was stopped down.)
The good news is that it *has* improved. However, some of me still thinks it may be a bit off, especially when folks have claimed this lens *can* be sharp corner to corner wide-open.
Here's an example image taken at 15mm f/3.5. Note that this was shot in RAW and posted onto the forum. I've done no editing to it and have left Adobe Camera Raw at all default settings. Also, all of these 100% crops were taken from the very edge of the frame.
(Oh yeah, another brick wall. I'm almost excited...)
Upper Left Hand Corner
Lower Left Hand Corner
Upper Right Hand Corner
Lower Right Hand Corner