Bahtinov Mask 8in Schmidt-Cassegrain Telescope

thingiverse

I designed my own custom version of a standard Bahtinov focusing mask using free online software. The general profile for the structure was generated automatically by the utility at http://astrojargon.net/maskgen.aspx. I adjusted the inner and outer diameters to fit my Meade 8" LX200 ACF Schmidt-Cassegrain telescope, but you'll likely need to adjust these sizes for your own scope. I also wanted a convenient way to insert and remove the focusing mask even with a dew shield or lens hood in place. To achieve this, I added a center peg that's easy to grab. This design also has an additional benefit: it ensures that the mask only inserts until it hits the front of the secondary mirror obstruction ahead of the corrector plate. I set this depth so there's always a small gap between the mask and the corrector, preventing any contact with the glass. The outside diameter of the mask touches the metal ring protecting the corrector around its outer edge, again to avoid touching the glass. Here are three models: a Fusion 360 parametric file, a STEP file, and an STL file specifically designed for this scope.