Interested in getting a polarizer for my new Zeiss 21mm Distagon which I use on a Canon 5D. Will the B+W slim still result in corner cutoff? Any experience?

What a coincidence!

I am interested in getting a Zeiss 21mm Distagon for my B+W slim polarizer!

OK - enough with the funny stuff. I have no experience with this lens (wish I did) but I recall you are planning to mount it on a 5D, right?

If I were a betting man, I'd say you should be alright with the slim mount polarizer. I mean, if not that, there isn't any other option, right?

I don't know about the specific thread size of that lens, but one thing I've always liked about Nikon's polarizers is that they're cut oversize so that vignetting isn't a problem.

They're pricey, but you might look into what's available.

you might be interested in some advice I received from other forums. One member advised that I use a 82-86 stepup ring, a slim mount 86 B+W and he special fit a 105mm hood. This is of course an extreme solution..but it implies that the 82mm might vignette..even the slim version. Any experience out there?

I have the lens and this polarizer and on slide film in the RTS3 you see no problems. Although I also have a 1Ds Mk2, I have never used the wide angle on the Canon.

Jens