Astrodon 36mm OIII Filter 3 nm FWHM

The Astrodon OIII & SII filters have become the preferred choice of imagers for the following important reasons:

• Parfocal with all Astrodon LRGB, C, and H-alpha filters eliminating the need for refocusing.

• A narrow 5 nm spectral bandwidth (full width at half maximum transmittance) consdered a "sweet spot" among commercially available filters to achieve the highest signal in the shortest time while keeping stars reasonably small.

• Incredible blocking of light outside the bandpass to better than 0.0004% to achieve very high S/N and high contrast, even with a bright moon nearby.