Very Good 1 3384

For the Canon must be applied and attentive to target the evil otherwise we risk putting the long and damaging the threads.
On the Sigma will screw it all alone without losing patience. the small screw is very convenient to rotate the filter to the desired position, without it we may skid and put our dirty fingers on the filter surface.
This screw can be removed to allow the sun visor clip, but do little to recover once the fixed sunshade and think not make settings of the filter with the visor especially for telephoto lenses, but difficult to find a solution to this concern.

Photo quality rendering filter is very valuable this actually changes the way photographing many and varied topics. I try to send pictures when I have time to test it in the best conditions.

Obviously with 10-22 vignetting is added, but not serious.
I would highly recommend this purchase!