Optolong H-Beta new filter 12 nm 1.25 inch for the Horsehead Nebula

The Orion Horsehead Nebula is visually a difficult object because it mainly emits light in a single line of hydrogen: the H-beta line. This filter, the Optolong H-beta 1.25 inch, lets a band of 12 nm through that line and blocks most of the other light. This makes such nebulae more visible.

You screw the filter into an eyepiece or diagonal mirror with 1.25 inch filter thread. In addition to the Horsehead Nebula, the California Nebula in Perseus becomes clearer as well. If you use 2 inch eyepieces, then there is same H-beta in 2 inch.

An H-beta filter works well only with a handful of nebulae and makes everything else darker. It works best with a telescope with a large aperture under a dark sky, such as the Classic Dobson telescopes.

If you are looking for a general-purpose filter for fog, then look at an UHC or O-III filter first. Filters for deep-sky observations.