Not sure this is the right mask for your telescope? Use our Focus Mask Finder — match your scope to the right Standard, Tri-Bahtinov, or Hyperstar/RASA mask.
Custom-fit Bahtinov focus mask for the Celestron 9.25" Classic SCT (pre-2008 models without Fastar/Hyperstar capability). Drops onto the front of your telescope, gives you perfect focus in seconds, and lifts off cleanly when you're done. Made in our own shop in the USA — American materials, American machinery, by Americans.
Fits pre-2008 Celestron 9.25" SCT OTAs without Fastar/Hyperstar capability. For newer C9.25 OTAs, use the Hyperstar/Fastar version of this mask.
Why a Farpoint custom-fit mask
- Drop-in fit, no fiddling. Sized specifically for the Celestron 9.25" Classic corrector plate. No screws, no pegs, no adapters — set it on, focus, lift it off.
- Made in the USA. Designed and manufactured in our own shop with American materials, American machinery, and American workmanship.
- Indestructible ABS plastic. Won't crack, warp, or shatter like aluminum or acrylic alternatives. Built to last decades.
- 15+ year track record. Farpoint has been making focus masks longer than nearly anyone in the hobby.
What's in the box
- 1× Farpoint Bahtinov Focus Mask, custom-fit for Celestron 9.25" Classic SCT
- Instructions for use
How a Bahtinov mask works
Place the mask over the front of your telescope and aim at a fairly bright star. Take a short exposure. You'll see three diffraction spikes — two angled spikes forming an X, plus a third central spike that's offset to one side or the other when the scope is out of focus. As you adjust the focuser, the central spike moves across the X. When it lands perfectly centered and symmetrical, you've hit optimum focus. Lift the mask off and start shooting.
A star coming into focus through a Bahtinov mask
Free software for precise focus measurement
If you want machine-precise focus instead of eyeballing the spike pattern, free open-source software can analyze the diffraction image automatically:
- Bahtinov-Collimator — a Windows tool that quantifies focus error directly from your image. Available on GitHub.
- APT (Astro Photography Tool) — Bahtinov mask analysis is built into APT's image-capture workflow.
Bahtinov-Collimator analyzing a star image for precise focus measurement
Want collimation help too?
The Tri-Bahtinov mask uses three different grid patterns to reveal both focus AND collimation errors in a single exposure — same drop-in design, more capability. We don't currently offer a custom-fit Tri-Bahtinov for the Celestron 9.25" Classic, but our adjustable line covers it. See all Tri-Bahtinov masks →
Related guides
- Focus Masks Buyer's Guide — material comparison, when to use which type, why custom-fit beats adjustable
- Telescope Collimation Guide — full walkthrough on collimating your scope
The unmistakable diffraction spike pattern at perfect focus
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