2.5nm Narrowband Oxygen III (OIII) Ultra Imaging Filter - 2"

The Antlia 2.5nm OIII Ultra Imaging Filter is an exceptionally narrow narrowband filter made from quartz glass designed to isolate the oxygen-III emission line at 500.7nm with a FWHM of 2.5nm, offering superior transmission efficiency exceeding 92% at the central wavelength. This filter significantly boosts contrast and signal strength in deep-sky astrophotography, particularly for planetary nebulae and supernova remnants, with an estimated 20-30% improvement in signal compared to broader 3nm filters. Featuring precision multilayer coatings with OD5 (0.001%) out-of-band blocking, it delivers exceptional durability and thermal stability while maintaining excellent parfocality, making it ideal for dedicated narrowband imaging with f/3.5 and faster optical systems.