Optolong L-Ultimate Dual Narrowband Filter - 2" rotator 5" Hexafoc focuser also helps

5" Hexafoc focuser also helps reduce vignetting due to its large diameter and makes focussing a joy - the smoothness and shifting-free operation sets a new standard in this price class

The filters are threaded on both ends

Anti-reflex paint for maximal contrast:

the whole construction is designed to be free from reflexes

Optolong L-Ultimate Dual Narrowband Filter - 2" rotator 5" Hexafoc focuser also helpsThe Optolong L Ultimate dual narrowband filter is designed to drastically reduce the effect of light pollution and capture a very specific wavelength of light emitted from deep space emission and planetary nebula. Its two ultra narrow 3 nm passing bands isolate the nebulae emissions in Ha (red) as well as OIII (green blue). This effectively means local light pollution is much less significant and even imaging during a full moon is possible too as all