Solar Filter Quick Reference Guide

Choosing a solar filter for your telescope can be a difficult decision when there are so many choices.  The best way to narrow down your selection is to find the filters that fit first and to find this out, you'll need your telescope's outer diameter.  

Measuring your telescope diameter is easy to do with a standard ruler. Be sure to measure across the widest part of your telescope where the filter will attach, to the outside edge of the telescope tube. Take your time to ensure an accurate measurement as you will need to be within a few millimeters for a proper fit. a Filter manufacturers typically provide sizes in millimeters.

Once you have your diameter, use this handy chart to find the filters that are right for you. Click the filter name to visit that filter's page on our site.  A filter must be larger than the outer diameter of your telescope or binoculars, but you do not want a filter to be more than 5-10mm larger than your outer diameter or you may not be able to get a secure fit.   Many filters are packaged with a small roll of self-adhesive felt to shim the filter.

Can't find something that fits or want to make your own filters? Checkout our selection of Baader Astro-Solar Film.