- H-alpha (7 nm), O-III (6.5 nm) and S-II (6.5 nm) bandwidths
- 2" mounted
- Precise filter curves for very good contrast
- Multi-layer anti-reflective coating
- Scratch resistant hard coating for long lifetime
- Identical filter thicknesses for parfocality
- Each filter comes in a high-quality carrying and storage box

Narrow band filters increase contrast by only allowing specific light wavelengths corresponding to certain spectral lines through, e.g. hydrogen (H-a, 656nm), oxygen (OIII, 501nm), sulphur (SII, 672nm), etc. The filters can always be used for photography, even when the Moon is in the sky, or as filters for light pollution in the city. Exposure time plays no role here - long-exposure photography can also be undertaken.

Optolong 6.5nm OIII Filter
OIII gas emits a beautiful blue/green color, and is highly abundant within emission nebulae. Centered around the 500 nm OIII wavelength and featuring a tight bandwidth of 6.5 nm, this Optolong OIII filter isolates this stunning emission from the background sky, producing high contrast images filled with nebulosity. This light-blocking nature means light from urban settings and the Moon are significantly less impactful on the quality of your astroimages as well. Combine the captured OIII data with H-alpha and SII data to create vivid Hubble Palette images, or get creative with other color combinations, such as the bi-color HOO Palette!

Optolong 7nm H-Alpha Filter
With hydrogen being the most abundant emission within our universe, this Ha filter is a key instrument, providing outstanding detail within your images. Centered around the 656 nm wavelength, all other wavelengths are effectively blocked out, making this filter perfect for imaging from the city or during gibbous Moon phases. The slim 7 nm bandwidth provides stark contrast on hydrogen nebulosity, highlighting intricate structure to take your images to the next level!

Optolong 6.5nm SII Filter
Sulfur, one of the many glowing gasses within emission nebulae, emits red light at a wavelength of 672 nm. This Optolong Sulfur filter is centered around this wavelength, and features a narrow bandwidth of 6.5 nm. With a bandwidth this slim, intrusive light from street lamps, surrounding houses, and even the Moon are of little concern, allowing you to capture striking detail on Suflur nebulosity amidst light pollution. A vital component to SHO imaging, this filter helps you create vibrant Hubble Palette images rich in color!

It is suitable for most emission nebulae, planetary nebulae and supernova remnants.