Optolong: The Optolong H-Alpha 7nm is a very narrow emission line filter that works by allowing a 7nm bandwidth of light, focused on the 656nm wavelength and blocking the transmission of light pollution wavelengths that they kill the contrast. The wavelengths that are responsible for natural light pollution, or sky glow, have radically declined, as has artificial light pollution caused by high- and low-pressure sodium and mercury vapor lights. The result is a high-contrast image that reveals the H-alpha line in all its brilliance.

This Optolong H-Alpha EOS APS Clip filter will provide a well-defined contrast between the parachute and H-alpha transmitting objects, but because it has a FWHM of only 7nm, you won't see the same number of stars in the final image as you would with the H-Alpha Optolong 12nm filter. Use this filter alone for CCD or DSLR imaging, or use in conjunction with the OIII 6.5nm and SII 6.5nm filters to obtain a tricolor image of vaporous nebulae from light-polluted areas.

The Optolong EOS APS H-Alpha 7nm filter is made with Schott glass that has been multi-layered with ion-assisted deposition technology to ensure scratch resistance and core wavelength strength, or CWL. The filter cell is made of light and resistant metal and is CNC machined, sandblasted, black anodized and finally laser engraved.