B+W 66-1066106 58mm 007M MRC Nano Coated Clear Glass Protection filter - XSPD Mount, Black

B+W make Great Filters, but a word of warning: if you propose using the filter on, for example, a Carl Zeiss OTUS 85mm f1.4 use the F-PRO mount instead.I know the mount thickness should be kept to a minimum in order to prevent vignetting, but I would much prefer a small amount of vignetting than a jammed filter, especially when used with an expensive lens.B+W use Brass to reduce the chances of jamming.Recently, I have found to my cost, there is a risk of jamming with the XS-PRO mounts above 86mm, especially if used with a none brass counterpart, in my case an aluminium screw-in lens hood. The aluminium is prone to “swarf pickup”.I think the problem arises from the fact that Brass and Aluminium have different Linear temperature expansion coefficients; 18-19 vs 21-24 and a combination of creep and thermal cycling cause the surface defects in the machined thread of the aluminium to “dig into” the brass.

The filter arrived dirty. After spending some time trying to clean it, I realised that the product must simply be defective as it had a mark I could not remove. On closer examination it looked like the glass was not very well bonded to the frame. I then compared the filter I received to a photo of it online, and there were subtle differences in the font placement. I had another B+W filter to compare it with, and the quality of my other filter was much better. I have since returned this filter.

I have recently bought my first APS-C DSLR (a Pentax K-X), and I soon realized that I needed a specific protection filter for its lens, especially since I intended to use the camera for some ultra-close up shots, which can be really dangerous for any lens (since you can literally bump into your subject or its surroundings, while looking for the perfect framing, with the actual danger of cracking the precious front surface of the lens...).I already had some old and cheap UV-filters for my 35-mm film camera already, but they were un-coated and totally useless, since digital camera sensors are already protected against UV rays, so these old filters just gave a purple/darker tint to the images shot with the new camera, introducing ugly flares and reflections on every shot including a front-facing direct light source.So, initially I tried to find the cheapest _coated_ protection filter I could find, but soon I realized that most of the cheapest one were either un-coated, or their coating was negligible, according to the opinions of other Amazon buyers. So, in the end I decided to buy this one, even if it costed slightly more than most other ones, due to the good reputation of this brand, and to its specific and peculiar characteristics.1) It is a _german-made_ "digital" filter, designed specifically for digital cameras, so no unwanted and useless "anti-UV" color casts or darker images;2) It includes a _real_ anti-reflective coating, a feature I could verify as soon as I opened its package, by simply looking at the very dim, dark green reflections coming from its front surface (to explain what I mean, try to compare the mirror-like reflections produced by a cheaply-coated or uncoated piece of glass/filter and the dim green or blue reflections produced by good, coated prescription glasses, or simply those produced by any good coated camera lens front glass...)3) It offers what the manufacturer calls XSPD mount, i.e. a _very_ thin mount that only leaves a minimal space between the back surface of the filter and the front surface of the lens, which is very important to avoid catching more reflected light rays between the two of them, and also reduces the total length/weight of the lens, especially if you are going to add more accessories/filters/converters/etc. in front of it;4) It is clearly manufactured in a professional way: it is very sturdy, even if very thin, and the glass does not wobble/rotate at all inside the frame, something that often happens with cheaper filters;5) It is packed in a nice and sturdy case including thick protective padding;6) The threading is incredibly precise, and - even on such a thin ring - it allows to mount more filters/accessories/etc. on the front of the filter. Moreover, there is enough space on the front to allow easily the insertion of a lens cap with springed "hooks" inside the filter;Considering that the price I paid for this filter, when I ordered it, was not excessively higher than the price of many sub-standard, no-quality, uncoated or falsely coated filter available, I consider it a real bargain, even if it just protects the lens and does not improve the image quality in any way: in my opinion, it is definitely preferable to invest a little more in an important accessory like this, rather than sparing a few pounds by choosing cheap ones, and risking to compromise the quality of ALL your shots with horrible reflections, think about it...After all, optics is one of those fields in which cheaper is _never_ better, believe me!

In an effort to help those trying to decide whether these filters are really worth the money, the following is a list of my own impressions and conclusions:PROS+ Employs Schott glass (made by Schneider Krauznach), which is manufactured to a very high optical standard+ Wide and shallow bezel - ideal with some wide-angle lenses, where vignetting could pose a problem+ The filter benefits from an effective seven-layer MRC (Multi-Resistant Coating), with an additionally hardened eighth (Nano) outer layer: it's hydrophobic, doesn't smear when cleaned, and is reputed to be as hard as the glass it adheres to+ Does nothing but protect the lens without impairing overall image quality (modern digital cameras do not require additional UV filtration)CONS- High purchase price compared to rivals- The mounting rings are so modest that making them from brass doesn't provide much of a benefit over cheaper aluminium alternatives- There are counterfeits in the marketplace, so try and purchase from a reputable sourceIn conclusion:If you habitually use very wide-angle lenses (as wide as 17mm on a full-frame camera, or 10mm on an APS-C camera), and you want to minimise the impact of vignetting in your photos, this B+W 58mm XSPD filter could prove to be an essential purchase. If you don't use lenses that go wider than 24mm (full-frame) and 18mm (APS-C), I would suggest that you buy the  B + W 58mm Clear Glass Filter Multi Resistant Coated  version instead - which is optically just as good and has much more substantial brass mountings.