A B&W 82mm #106 Neutral Density 1.8 Slim Glass filter has several uses and offers the possibility to achieve otherwise unachievable results. ND filters appear grey and reduce the amount of light reaching the film. They have no effect on color balance.
The reputation of B+W's Schott glass is world renowned. The high production standards combined with a sturdy brass filter ring make B+W filters hard to beat. These filters have a "heft" to them that is impressive. They may feel heavier but the benefit is in the construction and results. Not only is the glass exceptional but so is the seal between the ring and glass. Schott Glass used in the manufacture of this filter is legendary and synonymous with the highest standards of filter production. It comes with a solid 10-year warranty.
The filter ring is made from brass yielding a stronger product. Brass filter rings are also less prone to jamming. In addition, the seal between the glass and filter ring is exceptionally strong giving the filter added strength and durability.
In production, the filter glass is dropped into the empty filter ring from the rear and held in place with a threaded retaining ring; this is a definite advantage over a competitor who uses a spring clip to hold the glass in place. A threaded retaining ring will hold the glass firmly and securely in place to avoid the possibility of rattling and provide perfect parallelity and flatness to your front lens element for ideal optics. The part about additional filters not binding is due to the fact that brass is a very stable metal and does not contract or expand like alloy.
B+W slim filters are specifically designed for wide angle lenses. The slim design helps reduce or eliminate the effect known as "vignetting" which shows up as a darkening of the corners of the image. B&W slim filters are 3mm thick and are effective for lenses as wide as 17mm in the 35mm format. Slim filters do not have a front thread.