The Hoya Pro1 Digital Circular Polarizing filter is a very solid option among the crowded field of professional grade polarizing filters. Optically, it performs exceptionally well, producing images with excellent color and contrast without any noticeable color casts or image degradation. The filter’s ultra-thin lens frame does an excellent job of mitigating the effects of vignetting on wide angle lenses, and the knurled frame edges make handling and adjusting the filter a cinch.