Filter Question...Need some specific insight

[neuroanatomist]

Can't find or understand what the explanation for the term Extra Wide means. From what I've understood in the past the slim mount is the one for really wide angle glass

B+W mounts are as follows:

• Standard (aka F-Pro) - 5 mm thick, has front threads (standard CPL is 8 mm thick)
• XS-Pro - 3.4 mm thick, has front threads
• Slim - avoids vignetting by being thin, 3 mm thick, no front threads (Slim CPL is 5 mm thick)
• Extra Wide - (referred to as oversize in the B+W handbook, but EW on the B+W web catalog), avoids vignetting by having larger diameter glass, 5 mm thick (I think), has front threads, filter glass is wider than lens thread (e.g. a 77mm oversized filter will have 77mm threads on the lens end, but the filter glass, and the front threads, will be 82mm).

So, the slim mount will generally do a good job at preventing vignetting, but the extra wide filter will do an even better job and is useful in cases where even a Slim filter would cause vignetting. I don't think you'd need an extra wide for any Canon lens, more likely for a wide angle medium format lens or a view camera.


Regarding the various types (and prices) of polarizing filters, the linear polarizers are always cheaper than the circular polarizers within a given mount size and optical quality. Mount sizes increase in price from standard to slim to extra wide. Optical quality increases in price from non-MRC to MRC toKäsemann. There are some gaps (e.g. none of the linear polarizers have the MRC coating). There's often a big jump from standard/slim to extra-wide, because the EW filters have larger diameter glass which adds a lot to the cost.


There's a description of their mounts, except the XS-Pro which is somewhat new, and more information including tables of which filters are available in which sizes and mounts, in the B+W Filter Handbook.

[freelanceshots]

That's every thing I need to know. Thank you for the answers to my questions. I can now make a more informed buying decision.


So you think in your opinion that the EW version in 82mm is overkill for the 5D2 and 16-35mm combination. The Slim mount filter should be what I need and be a little less expensive then the EW.

[neuroanatomist]

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