Many different lens filters for photography are steadily being replaced with multiple-exposure camera tricks and post-processing software tools. However, one filter more resistant to this change is the circular polarizer (CPL). This special tool filters the light entering a lens in ways that software has yet to be able to mimic realistically. The resulting images when using a CPL are more saturated with color due to cutting down reflections of haze, water, and other surfaces in the world around us. In this review, I take a look specifically at the B+W XS-Pro KSM HTC-POL MRC-Nano Filter.
These B+W XS-Pro CPLs are constructed using Schott glass, Kaesemann polarizing foils, and brass filter rings. Together, these should provide proper optical clarity and accurate, neutral color reproduction. The glass has a number of anti-reflective coatings to reduce internal ghosting and reflections, something that cropped up in certain lighting when I used cheap CPLs. It also features a multi-resistant coating (MRC) with a top “Nano” coating which equates to easier cleaning and hopefully a longer lasting clean from dust and dirt floating around.
To avoid vignetting while attached to the lens, the CPL’s outer diameter is designed to be wider than the filter thread size. Depending on one’s lens, this can interfere with mounting a lens hood. For me using a Sony 70–400mm G II lens, this meant I would need to take the bayonet-style lens hood off, install the CPL, then refit the lens hood.
In use, I found the B+W XS-Pro CPL to be more stiff than what I’d prefer for rotating the filter and changing polarization strength. This may be a testament to how well it’s sealed, but it can still be a usability issue when I needed to spin it using only one finger through the lens hood window of my Sony telephoto. Instead of playing a game of “will it move,” I just opted to always go from the front of the lens hood with my fist of fingers (blocking the view) to get it right quicker.
Another issue with this circular polarizer is that it can be quite difficult to remove from the lens. On more than one occasion I felt like an idiot in public fiddling with trying to remove the filter for an embarrassingly long amount of time. I swear, people, I know how my camera works! Don’t look at me like that! After a while it can make one start to question which way it’s supposed to be turning, only to start going back and forth a few rotations each while onlookers dial the police. I’m unsure if this is something that will improve years down the line as the lenses and filter adapt to each others tolerances. I hope so.
The “high transmission” portion of its name refers to the amount of light allowed through. Depending on what your intentions are with this filter, this may be an extremely important detail. If a polarizing filter has outstanding optical clarity, why ever remove it? Well, these filters knock out some of the light as it’s being polarized before it reaches the camera sensor. That means lower shutter speeds or higher ISO settings. The B+W XS-Pro CPL’s product sheet promises 99.5% transmittance for its Kaesemann foils, or up to 1.5 stops of light loss. In my shooting, I saw about a one stop difference between having the filter on versus off. That’s not bad at all when it comes to CPLs, and another area where the cheap filters struggle to keep up. None of this really matters, however, if the plan all along is to mainly use the filter for cases such as knocking out reflections in long exposure flowing water images, and may even be seen as a negative.
The optical quality while photographing through this filter was very satisfying. My previous cheap screw-on filter had real issues with ghosting that drove me nuts because it was impossible to detect on the viewfinder and only became apparent at full scale on the computer. With the B+W XS-Pro CPL, everything I was getting from the naked lens was appearing sharp and clear as ever with it installed, even on a higher resolution 42-megapixel camera.
The full power of a CPL filter.
There was very little polarization here as the sun was behind me rather than at 90-degrees from my scene. However, there's still some subtle improvements between the on and off images.
What I Liked
- Doesn’t appear to affect image sharpness or clarity.
- MRC-Nano coating makes it easy to wipe clean.
- Good transmission of light; One stop difference in my use.
What I Didn’t Like
- Hard to remove.
- Rotating the polarization ring is overly stiff to engage.
- Interferes with some lens hoods.
While it suffers from some usability issues, I’m pleased with the final image output this polarizing filter produces. The B+W XS-Pro Kaesemann High Transmission Circular Polarizer MRC-Nano Filter is priced at $102.50 and is available now on B&H Photo.
Revision: A previous version of this article erroneously stated the filter came with a 10-year warranty. B+W has informed me this is no longer the case and is now covered under a 1-year warranty.