Bahtinov Mask Generator (3D-Printable STL)

A Bahtinov mask is a precision focusing aid used in astrophotography and visual astronomy. Placed over the telescope aperture or camera lens, it produces a distinctive diffraction pattern when pointed at a bright star. When the central diffraction spike is perfectly centered between the two angled spikes, your telescope is in critical focus — a method that is fast, repeatable, and highly accurate, even for beginners.

This Bahtinov Mask Generator creates a custom, 3D-printable STL file based on your exact telescope or camera dimensions. Instead of downloading generic STLs or manually editing OpenSCAD files, you can configure your mask directly in the browser, preview the geometry in 3D, and download a ready-to-print STL.

3D Printing Tips for Bahtinov Masks

• Print in black PLA or PETG to reduce internal reflections and light scatter.
• A 0.2mm layer height provides a good balance between detail and print time.
• Measure your telescope tube or lens carefully for a snug fit — small diameter errors can cause light leaks or poor seating.
• For Flat masks, use small screws through the mounting slots to hold the mask securely against the tube or dew shield.
• The gap width controls the diffraction slits. Smaller gaps increase focusing precision but require finer printing — ensure your printer can reliably produce the slit width you choose.

Why Use a Custom Bahtinov Mask?

A correctly sized Bahtinov mask dramatically improves focusing accuracy compared to live-view focusing alone. Generating a mask that precisely matches your telescope or lens ensures clean diffraction spikes and reliable focus every session.