The Series 7 UV/IR Cut MRC (Multi-Resistant Coating) Filter from B+W works by using its more than 30 multi-layered coatings on one side to interfere with the UV/IR radiation that can cause color changes and lack of sharpness in CCD cameras that do not contain an integrated IR filter. The other side of the filter has B+W's excellent multi-resistant coating that is harder, scratch, dirt and water-resistant. Wavelengths on both ends of the spectrum are affected by this filter. The UV and IR radiation are caught between these layers and eliminated. Standard lenses for CCD cameras are generally only corrected for visible light - not for UV interference. This filter eliminates the problems that result from this lack of compensation for UV and IR contamination. The filter appears clear to the eye and does not require any exposure compensation. However, due to the rules governing the physics of wide angle lenses, this filter is therefore not suitable for lens systems with an angle of view of more than 60°.
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 Multi-Resistant Coating (MRC) is harder than traditional B+W glass. This helps prevent scratches as well as being water and dirt repellent.
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.
This filter uses B+W's standard F-Pro mount which is now thinner than their previous filter mounts. It is thin enough to be used with 24mm lenses on a full frame body without the irritating effects of vignetting (the darkening of the image corners due to the filter ring intruding into the frame). F-Pro's also have an updated filter retaining ring that now holds the glass in from the back. The advantage here is that if your filter should get screwed on too tight, when twisted off, the ring is no longer in danger of being damaged.
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 parallelism 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.
- Eliminates UV/IR by interference rather than blocking technology
- Completely colorless glass carrier coated with a number of extremely thin, partially reflecting layers with precisely computed thicknesses, similar to MC coating
- Affects the wavelengths on both sides of the visible spectrum with a steep cut-off
- More than 30 interference coatings are vapor-deposited on one side, while the opposite side is MRC-coated
- When viewed at an angle, the filter appears to take on a tint that is caused by the filter working to eliminate the UV/IR rays. The color of the reflected light changes, with a similar effect on the light traveling through the filter