ZWO Seestar S50 filter adapter

ZWO Seestar S50 filter adapter - for M48x0.75 (2 inch) threaded filters

This simple filter adapter is threaded so you can screw in M48x0.75 threaded filters, the typical “2 inch” filters and the adapter slips into the Seestar S50 objective.  If the fit isn't tight enough, you could add a small piece of tape or even print at slightly oversize.  The threads are very fine pitch, so either print with fine layer lines or use variable layer height and print at least the threads with very fine layer height - 0.10" or smaller.

New updated design with multiple spring-loaded tangs along periphery to help hold it in place.

If you want to use a filter with a light/dew shield, I have a design for that here: https://www.printables.com/model/1275758-zwo-seestar-s50-baffled-lightdew-shield-for-use-wi

Update April 2026: slightly improved design to improve tab strength.