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Narrow band filters increase contrast by only allowing specific light wavelengths corresponding to certain spectral lines through, e.g. hydrogen (H-a, 656nm), oxygen (OIII, 501nm), sulphur (SII, 672nm), etc. The filters can always be used for photography, even when the Moon is in the sky, or as filters for light pollution in the city. Exposure time plays no role here - long-exposure photography can also be undertaken.
The IDAS-NBZ is a new, dual UHC narrow band filter for H-alpha and OIII ranges.
It also counteracts light pollution and considerably increases the contrast within many nebula structures. The NBZ has a very high transmission of 96% and is in no way inferior to other IDAS filters in terms of quality. The filter can be used for observations and photography (DSLR photography) and can even be successfully used on an extremely high-speed RASA or Hyperstar systems with an aperture ratio of up to f/2. This NIR range is blocked up to 1200nm.
As a dual filter, the NBZ allows both oxygen and hydrogen lines pass through. The oxygen range (OIII) is between 495.9nm and 500.7nm here. The hydrogen lines (H-alpha) are allowed through at 656.3nm.
