Review on Canon 17-40mm f/4L EF Ultra Wide Angle Lens: A Must-Have for Impressive Photography by Stanislaw Golkowski ᠌

Not always sharp at the maximum hole, but does an excellent job with apertures from 5.6 mirrors, posters - at a wide angle, (64) mm, not bad as a moderate portrait. Pros below: Working hole 5.6-8 All image distortions at a wide angle are easily corrected in FS. Cons below: - the mechanism is visible.