OIII-CCD 6.5 nm Deep Sky Imaging Filter:
This filter is an extra Narrowband OIII-CCD 6.5 nm filter. It is designed for nebula observation allowing 6.5 nm bandwidth of light centered on a wavelength of 500 nm through, which corresponds to OIII emission lines, and reducing the transmission of certain wavelengths of light, specifically those produced by artificial light including mercury vapor, and both high and low pressure sodium vapor lights and the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow).
OIII emits 495.9 nm and 500.7 nm and it is a blue-green colored filter. Many of images of planetary nebula and supernova remnants are taken only with H-alpha and OIII filters. They show great structural details, but have natural colors, looking like an RGB image.
Main Use and Performance