Bahtinov focus mask for camera lenses with 77mm filter threads. Snaps into the threads of an inexpensive 77mm UV filter (one-time install). From there, screw the filter onto your lens for a focus check, then unscrew it to shoot — quick and tool-free. Made in our own shop in the USA — American materials, American machinery, by Americans.
Works with any DSLR or mirrorless camera lens that takes a 77mm front filter. UV filter sold separately — any inexpensive one will do.
Why a Farpoint DSLR lens Bahtinov
- Mounts in a 77mm UV filter. Snaps cleanly into the filter threads of any inexpensive 77mm UV filter — focus by screwing the filter on, shoot by screwing 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, 77mm filter thread
- Instructions for use
What you'll need
An inexpensive 77mm UV filter, sold separately at any camera shop or online retailer. The Bahtinov mask snaps into the filter's threads — you only have to do this once. From then on, the filter-and-mask combo is what screws on and off your camera lens whenever you need to nail focus.
How a Bahtinov mask works
With the mask snapped into your UV filter, screw the filter onto the front of your lens 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 lens is out of focus. As you adjust the focus ring, the central spike moves across the X. When it lands perfectly centered and symmetrical, you've hit optimum focus. Unscrew the filter and start shooting.
Threading tip: only thread the filter on about half a turn once the threads grab. That's enough to hold it secure for focusing, and makes it quick to remove without overtightening.
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
Need a different filter thread size?
We make Bahtinov masks for filter threads from 52mm up to 82mm, plus square versions for Cokin P/Z holders and other large filter systems. See all DSLR lens Bahtinov masks →
Related guides
- Focus Masks Buyer's Guide — material comparison, custom-fit vs adjustable, choosing the right type
The unmistakable diffraction spike pattern at perfect focus
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