Optolong filter

This filter is designed to improve the contrast of deep-sky objects and attenuate the brightness of the sky in the background, thanks to a sophisticated transmission that allows the light of the lines in which the deep-sky objects shine (H-alpha, O-III , N-II, H-Beta, S-II…), but blocks harmful light emissions (for example the Hg line, or the wavelengths of sodium vapor lighting). It also reduces the background brightness caused by the oxygen in the atmosphere (“sky glow”). The use of this filter is recommended in areas with light pollution and is suitable for both visual and photographic use.

Compared to other filters for reducing the effects of light pollution, such as UHC or CLS filters, this multiband pass filter only has a minimal impact on color rendering. Therefore it is suitable for photographing objects that emit continuous light: not only emission nebulae, but also galaxies, star clusters, reflection nebulae, etc. You can achieve exposures up to 3 times longer than exposures without a filter.

Features of the treatment:

The treatments are not cemented onto the optical support, but spread by electron beam evaporation and subsequent ion beam-assisted deposition (IBAD process). This special process allows for extreme durability and scratch resistance, ensures central wavelength (CWL) stability and prevents thermal drift. Furthermore, it allows high transmission in the passband and high optical density in the blocked frequency range.

Attention, this filter must never be used alone for observing the Sun!