Optolong Filter
This filter is for improving the contrast of deep-sky objects and dampening the sky background. This is achieved through a complex transmission characteristic which lets the lines of deep-sky objects pass but suppresses many sources of light pollution. Additionally, the unwanted sky background, caused by oxygen emissions in the atmosphere ("skyglow"), is reduced. This filter comes to use especially in light-polluted areas and can be used visually as well as photographically.
Unlike other filters which should attenuate light pollution, like UHC or CLS filters, this filter is a multi bandpass filter which has only minimal impact on the color rendition, so this filter is also suitable for photographing continuum sources like galaxies, globular clusters and reflection nebulae.
- blocks UV and IR (700 - 1100 nm)
- high transmission at passband
- only minimal impact on the color rendition
- high optical quality
