This Olivon filter is designed to block out the wavelengths of light emitted by mercury-vapour light and other common causes of light pollution. This Light Pollution Filter is designed to screw onto the back of 1.25″ barreled eyepieces. This contrast enhancing anodized aluminium, optical glass filter provides higher transmission at the critical hydrogen-alpha and hydrogen-beta lines of the spectrum. It makes bright, light polluted skies appear darker, with the contrast increased between the object viewed and the surrounding sky. The contrast effect is particularly apparent when observing nebulae. Views of galaxies and star clusters are also enhanced, but to a lesser extent. This filter also improves the contrast of red spectrum planetary details.
This Light Pollution Filter works well with all telescopes, but works best for smaller telescopes, up to 114mm in aperture, when conventional light pollution filters often block too much of the light from the night sky that you actually want to see.