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     Winfried Rating: N/A |
The primary goal of coating actually was reducing internal reflections. A single layer coating will reduce reflections in a certain range of wavelengths of the light only, so the light transmission of single-coated lenses will not be even over the entire spectrum of light. So manufacturers introduced techniques of giving different kind of coating to the single lens elements of a lens. Later multicoating was introduced which allows to control the color balance of a lens which might be disturbed not only due to the properties of a single-layer coating but also due to the properties of some optical glasses which also do not have even light transmission, i.e. in most cases they will give a yellowish tone. To compensate this, manufacturer use coatings which have slightly more reflection of the yellow part of the spectrum, thus compensating the absorbtion of blue light. |