David Choo , May 24, 2004; 05:17 a.m.
When comparing Hoya S-HMC vs S-HMC Pro 1, in terms of image quality, you will find absolutely no difference.
If you use super wide angle lenses, the Pro 1's might be a good investment. Althought I never vignette with the non Pro 1's at 16mm. I think this has more to do with construction of the lens by the manufacturer you use.
I personally don't use more then 1 filter at a time, unless its some type of color correction filter with a ND grad like the Lee system, in which case, the regular S-HMC are just fine, even at 16mm.
In terms of polarizers, I do believe a slim line version is well worth the investment.
B+W MRC filter quality is the same as the Hoya. You'll be hard pressed to find any difference. I use both and have never found a difference in quality between the two.
The two differences I found which can be incredible important are the fact that B+W uses brass rings. (Not everyone needs this) And B+W usually has less of a f-stop loss as compared to other manufacturers.
Hope this helps.