Baader f/2 Highspeed-Filter Set 31 Halpha-O III-S II

The Baader f/2 Highspeed-Filter Set 31 Halpha-O III-S II specially designed for the special filter requirements when used with high-open optics, especially Celestron Hyperstar or RASA. Conventional narrow-band filters suffer from a high transmission loss due to the central wavelength (ZWL) displacement when used at high-opened optics, in extreme cases the may even be outside of the half-width (HWB). The ZWL was therefore adapted for f / 2, the layer system was optimized for maximum freedom of reflection for the extremely wide beam. The HWB of these filters is optimized to f / 1.8 to f / 3.5 to deliver the highest contrast despite the high line broadening of such openings. Only with these filters can extremely fast optics in fog photography really be used effectively. Between f / 1.8 and f / 3.5 these filters provide a significant improvement.

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