Quality begins in front of the lens, and as is generally known, that is where the filter is. A filter must not restrict the performance of the photographic lens. An important criteria for a perfect B+W filter is a high-quality coating, also known as an anti-reflection coating. With a B+W filter, such layers are evaporated by means of thin-layer technique, a quite complex coating process. The coating material consists of special substrates that are applied in one or more layers depending on the coating system.
|B+W COATING||B+W E||B+W MRC||B+W MRC nano|
|Single Coating||Multi Resistant Coating||Multi Resistant Coating nano|
|Number of Layers||2||16||16|
|1 Layer per side||7 + 1 Layers per side||7 + 1 Layers per side|
|Reflection||~ 4%||< 0,5 %||< 0,5 %|
|Transmission||~ 96%||> 99,5%||> 99,5%|
|Easy to clean||±||+++||++++|
|Made in Germany||+||+||+|
A coating changes the reflection properties of an optical surface as in the case here of the filter glass. An uncoated glass surface reflects about 4% of the incident light rays on each glass surface. The system of thin, vaporized layers is configured in such a way that less light is reflected and more light passes through the layer itself and the glass. In this way, higher light transmittance is obtained which enables brighter colors and higher image contrast to be achieved.
B+W filters are always coated on both sides. Consequently, ghost or double images, which can be caused by back-reflection from the image sensor, are attenuated many times and, depending on the shooting situation, completely eliminated.
With the B+W single layer E coating, the light reflection on the filter surface is reduced to an average of less than 2%. With perfected multi-layer systems such as the B+W Multi Resistant Coating MRC and MRC nano, this residual reflection is well below 0.5% and is thus practically reflection-free:
|Light incidence on an uncoated filter: about 4% is reflected||From the surface of a B+W E coated filter, roughly 2% of the incident light is reflected||From the surface of a B+W MRC nano coated filter, roughly 0.5% of the incident light is reflected|
Representation as a Reflection Curve
In addition to its anti-reflection properties, a coating also protects the surface of an uncoated filter. High-tech coating systems such as the B+W MRC and B+W MRC nano have an extra outer layer with an increased hardness that provides additional protection against scratches. This layer is dirt and water-repellent that makes cleaning a B+W filter considerably easier.