Glad to help!


I think you'd be ok with a Slim CPL - you might get a small amount of vignetting, though. Looking back over my post, I was thinking primarily of the UV filters, not CPLs. I don't have a 16-35mm to test (yet), nor an 82mm Slim CPL (although I will likely get one, since it will be useful on the TS-E 24mm I just got). Previously, I did some testing on filter mount thickness and vignetting on the EF-S 10-22mm (16-35mm FF equivalent angle of view). For the 10-22mm at 10mm, I could stack 8.4mm of filters (thicker than a standard CPL) with no mechanical vignetting. Of course, The EF-S lens is f/3.5 at the wide end, not f/2.8, and it's a smaller image circle, so it's not directly equivalent. I do notice that Bryan's vignetting results show a comparison of the 16-35mm II with no filter and with a B+W standard mount UV filter. There is a very small effect on vignetting (look at the EV line positions, not the overall brightness of the images, since the exposures appear a little different). Since the standard F-Pro mount is the same thickness as the Slim CPL, I'd expect you'd see similar results.


--John