When it comes to camera gear, filters aren’t exactly something to get excited over. Especially the mundane one like protection/UV filters. That said, there’s always room for improvement in filter designs, and a number of manufacturers are still competing in that field to produce better professional level filters.
In 2008 B+W introduced their XS-Pro line of premium quality filters. The XS-Pro mount offers users the same high optical quality filters in a thinner package without giving up features. Moreover, the XS-Pro line is the only line of B+W filters that currently use their MRC Nano coating system, which B+W claims provides superior water repellence than the older MRC coating.
Currently B+W only offers a small selection of their overall filter catalog in XS-Pro mount. The current selection is limited to UV, clear protection, circular polarizers, and a variable ND filter.
For this review, I’m using a 77 mm XS-Pro 010M UV filter as the test bed. However, you can easily extrapolate performance to most of the rest of the XS-Pro line—at least for the most part. All of the XS-Pro filters share the same MRC Nano coating, so the coating tests should apply regardless of the type of filter. Likewise, the XS-Pro Keasemann polarizer uses the same polarization foils as the F-Pro one I reviewed previously.
The only exception to that rule is the Vario ND filters. They use an aluminum for the ring instead of brass, and since I don’t have one to test with, I can’t speak about them specifically.
Ring and Build
The most obvious change from the F-Pro series, and we’ll all of B+W’s old filter lines, is the new mounting ring. UV and clear protection filters are only 3 mm thick, compared to 5 mm for the F-pro filter. Even better the circular polarizers are only 4mm thick, compared to the 7mm of the F-pro line.
What might be even more impressive is that B+W is using the same black chrome plated brass to do this as they were on their old slim filters. B+W claims that the advantage to brass is that it won’t bind when attached to a lens the same way that aluminum does. I can’t say for sure how true that actually is, mostly because I’ve been using brass B+W filters for as long as I’ve been shooting with lenses worth more than $100.
In and of itself, the thinness isn’t especially new. B+W had a line of slim filters that were similarly thin, with 3 mm thick non-polarizers, and 5 mm thick polarizers. The real difference here is that these filters have front threads, while the previous slim filters didn’t. Having front threads is a big deal. At a minimum, it means you can use a regular clip on lens cap without having to take the filter off, or you can screw your Lee or similar mounting rings right into the XS-pro filters.
That said, not all applications need a slim filter, even if I find they look better on the lens. Where slim really matters is when you’re using ultra-wide angle lenses. In many cases the difference between vignetting and not when you’re talking about a 16 mm lens on a full frame sensor (or 10 mm on APS-C) is only a millimeter or two.
Vignetting on Ultra Wides
B+W’s literature for the XS-Pro filters suggests that they shouldn’t vignette on a 17 mm lens on a full frame camera or a 16 mm lens on an APS-C camera. Unfortunately I can’t test all possible ultra-wide angle lenses so. For these tests, and for the moment, I’ve only looked at Canon’s EF 16–35mm f/4L IS USM zoom. I’ve made a number of test images from the bare lens without a filter to the XS-Pro protection filter and Lee’s wide angle adapter and filter holder.
I’m still working on developing a solid testing protocol for vignetting—not just for filters, but for lenses as a whole—as such I can’t say anything here with any definite certainty. Moreover, I’ve only had the XS-Pro protection filter and the Canon EF 16–35mm f/4L IS USM
The current state of the art coating from B+W is their MRC Nano coat. MRC Nano is a multi-layer coating process that reduces reflections and repels dust and water.
B+W rates their MRC and MRC Nano coatings as transmitting 99.5% of the incident light. Visually inspecting a clean MRC Nano coated UV filter and comparing it to a clean MRC coated UV filter, I can’t discern much if any difference in transmission or reflections. Both are extremely clear, both exhibit no noticeable differences in reflections.
The similarities in transmission/reflection performance is not unexpected. B+W’s nano-scale coating, unlike those by Canon or Nikon, isn’t aimed at altering the reflective properties of a air-glass boundary, but rather at improving the water repellant nature of the filter.
For me, the biggest reason to want a water repellant coating is to be able to keep shooting in rain and spray conditions. In these conditions, water droplets are typically small enough to cause issues with image quality (especially reducing contrast and clarity) while never getting big enough to become big enough to have the mass to break the surface tension and roll off the lens.
To test these kinds of conditions, I’ve used a misting spray bottle to produce a fine mist. The results are show below. I’ve compared 2 different filters, the MRC Nano coated B+W, a previous generation MRC B+W filter. My test methodology was simply to spray the filter (held vertically) with a fine mist spray until a droplet gained enough mass to roll down the front surface of the lens. I recorded these at 120FPS, so more detail could be seen.
This first video shows my water spray test with a B+W XS-Pro filter and the MRC Nano coating.
As a point of comparison, this second video shows the same test preformed with a B+W F-Pro filter that is only MRC coated.
There are certainly differences between the new and old coatings in terms of the way water behaves on them. However, I’m not amazingly impressed by the new coating, though it’s certainly better. Droplets beaded up far quicker, and ultimately sheeted off far quicker. But in the fine mist of my spray bottle, either filter on a lens would produce an equally unusable image.
I’ve always been a fan of B+W filters. They’re well built and have solid optical performance. The XS-Pro line takes the solid filters of the F-Pro line and makes them thinner without compromising on features. For protection filters, I’m not sure there’s a reason to continue to use the old F-Pro line. The question is less clear cut with the circular polarizer and variable ND.
That said, an upstart to the industry has come along since I wrote this article; Breakthrough Photography. And after testing their filters, I’ve found a lot of compelling reasons to choose them over B+W. If that sounds interesting to you, check out my review of their X4 circular polarizer.