I just tested this circular polarizer filter and I found two problems; I initially had a lot more difficulty screw on the objective that the protection filter "CANON" bought as a first line; but the most unpleasant surprise is the lack of female thread on the outside of the filter, which prevents the use of the lens cap before. After each use, it is imperative to replace the filter in order to replace the cap before goal. This drawback makes me regret my purchase and consider replacing. These concerns do not compromise the optical qualities of this accessory that has worked well in sunny weather (best dive, sharper color, mitigation of reflection ...)