Quote Originally Posted by Poisson Du Jour View Post
Contrast is strong and uniform across its range and in my long experience (since 1998) the best images are found at f8, but it also delivers wide open at f4.
Somewhat confusing statement there. The 17-40L was introduced in May 2003. I suppose what you mean to say is that, generally speaking, lenses perform best at f/8, but that this particular lens does well at f/4 too.

I second that impression BTW, although I usually stop it down to f/5.6, where my sample improves by a visible amount, especially at the long end. The performance improvement going from f/5.6 to f/8 seems much smaller.