Industry filters in planetary astrophotography
For industry and scientific use a lot of various filters is being made. For astronomy we have a lot of Baader, Astronomik, Astrodon and other filters, but still some of those "industry" filters can be used in astronomy for advanced imaging. For DS imaging we can dig out narrowband filters for helium, neon or argon. For planetary - various infrared and UV filters.
Industry filters are made by various companies. Edmundoptics makes a lot of them - from simple to advanced bandpass filters. Eureca.de has narrowband filters, and thorlabs.de also has nice set of them. Prices are low for simple Schott/Hoya filters and can rise very high for narrowband filters. I've bought and tested few simple Schott filters from UQG Optics.Filters are available in various sizes. 25 mm diameter is very close to the 1,25" size standard and can be mounted in filter cells of cheap SkyWatcher/Celestron moon filters: