Customizable Astronomy Focus Mask

A customizable OpenSCAD (free and open source: https://openscad.org/ ) focus mask generator.

Can generate masks for various telescope types and photo camera lenses as a filter via the OpenSCAD customizer (https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/Customizer#Activation_of_Customizer_panel ). Essential settings are:

• inner diameter
• focal length
• type of central obstruction
• height
• type of mask

Included examples are for a Skywatcher Evouide 50ED, Skywatcher Explorer 130-PDS, Nexstar 5SE and a Sigma 18-300 camera lens (with 72mm filter thread).

Supported masks:

• Bahtinov https://en.wikipedia.org/wiki/Bahtinov_mask
• Tribahtinov (3 Bahtinov masks in 1)
• Hartmann https://en.wikipedia.org/wiki/Hartmann_mask
• Carey https://en.wikipedia.org/wiki/Carey_mask 
   

Easiest and most accurate to use in my opinion is the single Bahtinov variant.

PLA works well. Color, preferably something dark, though white masks just work.

Most masks can be printed just fine with a 0.60 mm nozzle with 0.30 mm layers. Tested up to 240 mm focal length for my Evoguide. Smaller nozzles sizes might print a more precise mask for lower focal lengths.

Thread support with Dan Kirshner's threads.scad: https://dkprojects.net/openscad-threads/ 

Presets are available in the masks.json file. If you want to have a preset included for your setup or need help with creating a specific mask, leave the settings as a comment.