- 1) Range of focal lengths. 2) Fixed aperture F4 3) Ability to use filters 4) Removable lens hood included 5) Good workmanship 6) Acceptable level of chromatic aberration 7) Acceptable level of geometric distortion 8) Internal focus.
- 1) Aperture F4 - I would like more, the lens is dark. 2) Sharpness - not really soap (especially if you remember that this is an over-wide), but you still want more contrast and clarity of details (Canon EF 17-40 F4 L loses in sharpness) 3) Autofocus - slow, loud, sometimes inaccurate (tested on 650d and on mark2) 4) The lens can "suck" dust when zooming.