Each additional glass layer, which is introduced into the optical path, inevitably affects the entire optical system. Protection filters are naturally so a minimal effect on the optics. To succeed, the so simple-looking glass parts must have the highest demands in terms of flatness and reflection freedom, are ergo highly precise Beuteile. Man saves clearly in the wrong place, if you do this in the protective filters used.
B + W filters the separator Optics Works in Bad Kreuznach is a long-established specialist in the production of high-quality, professional optics and photographic filters. Native resolution test with Canon L lenses have shown that cause the B + W filters in comparison with many other filters only minimal impairments and are therefore my first choice.
Conclusion: Not the cheapest but one of the best filters I know. In both the optical as well as in the mechanical workmanship worth every euro! Buy recommendation!
