Optolong 3nm SHO 36mm Unmounted Filter Kit

Optolong 3nm Filter Kit - 36mm Unmounted

This SHO filter kit from Optolong comes with 36mm unmounted 3nm H-alpha, SII, and OIII filters. This filter kit will give astrophotographers higher contrast, greater detail, decreased background noise, and increased faint nebula signal. The SHO 36 mm filters work best with monochrome cooling CCD astronomy cameras and modified DSLR imaging in each channel. The HA, OIII, and SII correspond with the RGB channel, allowing imagers to process Hubble images with post-processing astrophotography software.

Optolong uses a multi-layer, anti-reflection coating on each of the three filters. Each filter uses a non-cementing optical substrate coating, which is applied through precision Ion-based deposition, providing durability and resistance to scratching. It also provides stability on the central wavelength so there is no deviation depending on temperature change. Their planetary rotation system gives precision and homogenous coatings to ensure high-value pass-band transmission and off-band optical density.

The Optolong H-alpha filter is narrowband and allows 3nm bandwidth of light, centered on a 656nm wavelength, through. This popular type of filter is perfect for those looking to have better contrast and the ability to capture subtle nebula details. OIII (Oxygen IIII) CCD filters like this 36 mm Optolong OIII extra narrowband filter, allow 3nm bandwidth of light, centered on a 500nm wavelength, through. This corresponds with the OIII emission line. OIII filters emit 495.9nm and 500.7nm and are blue-green colored filters. When coupled with the H-alpha filter, users will get incredible images with great structural details and natural colors, like with an RGB image. With the coating optimization, Optolong has ensured that this OIII filter does well with bright stars after performing a qualitative halo test. The SII (Sulfur II) CCD filter is an extra narrowband filter and designed for nebula observation. The SII filter from Optolong allows 3nm bandwidth of light centered on a wavelength of 672 nm though.

All three of these included filters reduce certain types of light transmission like artificial light from mercury vapor and both high/low pressure sodium vapor lights. They also block natural light transmissions caused by neutral oxygen emission in our atmosphere, often called sky glow.