I wanted to buy a nebula filter, and I saw two kinds.

UHC light damage filter transmits more light than nebula filter, and their functions overlap, so it is mainly used for astrophotography.

UHC optical loss filter mainly blocks artificial light and light scattered or excited by the atmosphere, and belongs to broadband filter.

Nebula filter is a kind of narrow-band filter, which mainly transmits light with a specific wavelength of the nebula and blocks light with other wavelengths.

If the astronomical society only looks at deep space objects with the naked eye, it doesn't need any filters. If you have to buy a filter, buy a UHC optical loss filter, which will help you see the stars with the naked eye.