B+W Filters are the Bees Knees
B+W filters are the best filters I have ever used. Made in German by Schneider, a leading manufacturer of high-quality view camera lenses, I'm happy in the knowledge that, unlike cheaper plastic ringed filters, B+W filters won't lessen the quality of my high priced Nikon and Leica-M series lenses.
I use B&W Polarising filters exclusively
Made to the highest of standards, from arguably the world's best optical glass, it's worth considering filters that incorporate the B+W F-Pro filter mount. The result, a thinner design that helps prevent vignetting, even on wide angle lenses, including most 24mm focal lengths on full frame camera bodies (i.e. Canon 5D Mark III and Nikon D800/e).
Made to last and encased within a brass ring to ensure that the filter thread won't become cross threaded if screwed on too tightly to your lens, a common and potentially expensive problem with cheaper filters utilizing plastic threads.
Why I Use a Polarising Filter
I employ a polarising filter for three specific reasons which I can detail as follows:
* To increase color saturation (i.e. purity) and maintain texture under conditions when bright light might otherwise cause color and texture to be reflected off the surface of the subject (e.g. wall, leaf, rock) and away from the lens.
* To reduce reflections on non-metallic surfaces. This might allow you to photograph window displays or someone swimming under water without harsh reflections on the surface of the glass or water messing up your picture with irrelevant detail reflected form outside of the picture frame. It's just like wearing polarising sunglasses on a bright day. If you or your subject is squinting it's probably a good day to employ the polarising filter.
* To deepen (i.e. darken) the color of an already blue sky and, as a consequence, emphasize the shape and texture of clouds
A polarising filter is actually to pieces of glass sandwiched together. To use the filter simply screen the inside end securely onto the front of your lens. It's then simply a matter of turning the outside filter ring, while looking through the camera's viewfinder, until the desired effect is, hopefully, achieved.
It's worth noting that a polarising filter, as it's actually made of two pieces of grey glass, absorbs light. It works or it doesn't, depending on the direction of the light. If you find yourself turning the filter without noticing any changes to the way your image looks then take it off. The fact that it absorbs light may be problematic as it will either cause you or your camera to lower the shutter speed, increase (i.e. widen) the aperture or increase the ISO. Depending on the circumstances these changes may have adverse effects on your photo. The lesson: polarising filters are great under conditions when they work. If you don't see any change with the polarising filter attached, take it off.
Be aware that a dirty filter will likely result in reduced contrast and image sharpness and, when photographing light sources (i.e. street lamps, sunrise and sunset) a blooming or spreading of the light and a smearing of color can result. Remembering to keep both the filter and the front element of your lens clean is, therefore, essential to extract the best quality from your lens.
B+W filters incorporate a special Multi-Resistant Coating (MRC) which provides the filter with a water and dirt repelling coating. This helps keep the filter cleaner for longer and, when cleaning is required, makes it easier to achieve.
The MRC coating also reduces internal reflections, between the filter and the front element of your lens, resulting in reduced occurrence of flare and ghosting.
I keep a B+W filter on my lens at all times. Usually it's a UV filter but, when its time to attach a polarizing filter, its removed. Never stack filters on top of each other. If you do you'll be courting poor quality and the increased likelihood of vignettes which defeats the purpose of buying great glass (i.e. lens and filter) in the first place.
Used correctly and under the right circumstances a polarising filter can really make a difference to your success as a photographer. And that's why I always carry one in my own camera bag.