Quote Originally Posted by Xander Fischer View Post
I'm talking about barrel distortion that causes verticals/horizontals to bow or bend. I've read that some 300mm lenses do exhibit some barrel distortion, and given that I shoot a lot of subjects with strong vertical/horizontal lines, I want to be sure that I'm getting the lens with least distortion.
What you've heard probably is in reference to 35mm zoom lenses. Rectilinear lenses have been manufactured for quite some time, and the lenses have been good for at least a century.