Celestron 1.25" Oxygen III Filter

Celestron OIII narrowband filters isolate only the two lines of doubly ionized oxygen (at 496 and 501nm wavelengths) emitted by planetary and emission nebulae, blocking all other wavelengths of the light spectrum. Using this filter often makes the difference between seeing and not seeing certain nebulae. The effect is particularly impressive with some well-known nebulae, for example, the Veil (in Cygnus) and the Helix in Aquarius. Without a filter, using small instruments, you often see nothing. With the filter, the nebula will be immediately visible! Each filter features a high-surface-hardness optical coating, deposited using high-vacuum thin-film deposition techniques. The coating uses the principle of optical interference and is designed to block the entire visual spectrum from 400 to 700 nm. This eliminates the unnatural colored halos around bright stars that are typical of O III filters built with less sophisticated high-vacuum deposition technologies. The filter diameter is 1.25". Celestron filters are designed to be screwed onto eyepieces of the corresponding diameter. In fact, all modern eyepieces are equipped with filter threads. Furthermore, Celestron filters are also threaded on the opposite side, with a female thread that allows you to screw multiple filters together if necessary.

Main features

Celestron quality for a reliable and rewarding observation experience.

• Filter diameter: 1.25"

Main technical specifications