The Alstar 2 Ultra High Contrast Filter is unbeatable for revealing nebulosity. The 2 Ultra High Contrast Filter is unbeatable for revealing nebulosity. This is achieved by passing three nebula emission lines- the two doubly ionized oxygen lines (496 and 501nm) and the H-beta line (486nm) -while blocking light-pollution and Sky Glow. The result is superb views of the Orion, Lagoon, Swan and other extended nebulae. The strictest quality control standards are employed... It filters out the brightening of the sky due to artificial light. The use of an UHC filter is not only useful at light-polluted sites; the contrast is also increased at dark sky sites. Can be used at both light polluted and dark sky sites; Blocks the light from mercury and sodium vapour lamps Can be used at both light-polluted and dark sky sites. Buy Fotociti Maternity Flare Leggings with Pockets Over The Belly,Women's Pregnancy Soft Yoga Pants for Casual,Workout Brown Alstar UHC filter is one of the most useful accessories you can have and no eyepiece case should be without it. The way an UHC filter works is very simple. As many celestial objects; such as nebulae; radiate at other wavelengths; a considerable increase in contrast can be achieved by this; The background sky appears darker and all at once; faint details become visible As many celestial objects, such as nebulae, radiate at other wavelengths, a considerable increase in contrast can be achieved by this. Alstar 2 Narrowband O-III Filter - Enhance Contrast The background sky appears darker and, all at once, faint details become visible. Nebula filter for increasing contrast, also suitable for use with smaller telescopes. The strictest quality control standards are employed throughout the production process. Observing first without and then with a UHC filter makes the presence of an object very obvious. Each Alstar Ultra High Contrast Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the O-III and H-beta emission lines. Nebula filter for increasing contrast; also suitable for use with smaller telescopes The result is superb views of the Orion, Lagoon, Swan and other extended nebulae. Blocks the light from mercury and sodium-vapour lamps. But also, highlights such as the Orion, Lagoon or Swan nebulae, show a whole new side to them. Contrast Filter Lumicon Ultra High LF3035 B&H Photo Video Light Pollution Filters