top optical performance, handling not without problems

Despite warnings from some customer reviews was deliberately chosen Hoya Pro1 Digital Circular, not You also wonder, because I already have some UV filters from Hoya and am convinced of their processing and performance.

The filter was purchased for use with Canon EF 24-105 or Canon EF-S 10-22 and immediately tested at these two glasses. My personal judgment:

Processing and handling:
(+) The processing of the filter is top notch, but what you would expect from a product in this price range quite well
(+) The filter ring is smooth but not too easy that it also maintains the set rotation position
(+) The mark on the rotary member allows fast setting (by the user) "predefined" rotational positions
(+) (Subjectively) provides with its antireflective bluish-compensation at each lens from just cool;)

(-) The extremely narrow threaded inner ring leads may cause the unscrewing of a challenge is -> So screw it possible not alzu fixed
(-) Lens cap can be put on, but does not sit flush with the filter ring. My two identical Canon lid then sit still stable enough.
(-) Makes this set in setter sun visor out of the way (even at wide open tulip shape of the EW-83E), the well-intentioned Slim version of the rotatable ring -> here the sun visor should, exceptionally, in the "parking position".
(-) Appears very quickly dust etc. attracting. Fingerprints are not as quick wipe again. And with the latter is unfortunately to be expected with a polarizing filter (unless you shoot only with gloves)

(O) the storage case is OK, although running "Hoya-typical" rather Spartan, could MMN in this price range a bit "valent" fail (s. Sigma-filter). But provides sufficient retention protection and is suitable for transporting.

Optical power at the EF-S 10-22:
(+) An absolute WOW effect, reinforced by an even and balanced picture across the entire image area. Less good filters are just at UWW lenses, (due to very acute incidence of light on the filter) an uneven picture (with respect to the filter effect, of course) provide. But not the Hoya Circ. Pro1 Digital! Here is paying the additional investment of over a less good filter.
Both 10mm and 22mm at absolutely top!
(+) By the physics of polarization reflect "bright" image areas noticeably less light so that the image exposure in favor of less bright areas will be optimized -> less spread in the dynamic range, allowing noticeably closer to what the human eye perceives -> more realistic images.

Attention! When harsh daylight of the blue sky is excessively dark blue, which though homogenized the overall dynamics, but no longer looks natural. This behavior can, however, easily turn the filter control at will.

(+) No additional vignetting as an advantage of the Slim version

Optical power at the EF 24-105:
(+) Of the WOW effect was limited, was nevertheless still a significant increase. Saturated colors (just to Canon bodys who preach the philosophy of natural color reproduction, a positive aspect).

(-) 1-2 aperture light absorption, which in no polarizing filter is however different.

Conclusion: for UWW highly recommended. Handling used to. Nevertheless, absolutely first-class filters!
Despite some criticisms full 5 stars from me.