Lu sur ladite brochure :
citation :
Tous les filtres B+W pour films couleur et noir et blanc, les filtres gris neutres, les filtres infrarouges
et les filtres spéciaux sont fabriqués en série avec traitement monocouche. Sur demande,
ils sont également disponibles avec traitement multicouches MRC. Les filtres polariseurs existent,
suivant le modèle, en version traitée multicouches MRC ou non traitée. Pour plus de précisions voir
tableau pages 47-49.
Pour les filtres suivants, le traitement multicouches n'apporte pas de bonification et n'est donc pas
appligué: filtres adoucissants, lentille à effet, filtres brouillard, spectra, Wish-trick, filtres à étoile,
double sunny, prismes.
Et sur le site de
Robert White, à propos des filtres BW :
citation :
Coatings
At first glance, the coating of filters may not seem particularly important, because unlike photographic lenses, they have only two glass air surfaces that can lead to reflections that reduce the transmission of light. This also applies to B+W Polarisers, because their Polarising foils are cemented between two glass discs.The coating of the front surface seems even less important, because the first reflection is directed away from the lens. In other words, it doesn't seem to generate stray light or ghost images. Do coatings even have any relevance at all? Considering that the transmission loss for both uncoated surfaces together amounts to only 8%.
However, closer examination shows that a high grade coating does indeed enhance image quality significantly, especially with high contrast subjects and when a light source (like the sun or a light bulb) is visible in the picture. Once again, with normal single layer coatings the loss of transmission for both surfaces on average amounts to only approximately 3%, whereas with more complex multiple coatings (MC) it amounts to a mere 0.5%. A more significant aspect than the gain in light transmission is the reduction of reflections and ghost images to about 1/3 with simple coatings, and to less than 1/16 with MC coatings. Coating is even more important when two filters are used in combination. Not only will the losses in transmission and the reflections be doubled with such combinations, but also there is the possibility of multiple reflections between the filters, which may cause disturbing double images when there are light sources included in the image area. Single coatings reduce the occurrence of double images to approximately 12.5%, whereas MC coatings reduce it to approximately 1.4%. MRC coating (Multi Resistant Coating) by B+W is not only an extraordinarily effective multiple layer coating, it is also harder than glass, so that it protects filters from scratches (for instance when cleaning the filters), and it is also water and dirt repellent, thus facilitating filter maintenance. All B+W colour filters for colour and black and white photography, as well as the neutral density filters 101, 102 and 103 normally have single layer coatings, and most of these filters are also available with MRC multi layer coatings. B+W Polarising filters have different coatings, depending on the type and on the glass diameter.
Quant aux Leica, je n'ai plus le lien, mais on en a parlé ici même sur un des sujets traitant des filtres UV.
Posté: mardi 29 mai 2007 - 22:32
le filtre IR est obligatoire 
