Adjustible Bahtinov Focus Masks
13 products
13 products
Not sure which mask fits your telescope? Try our Focus Mask Finder — match 191 telescopes to the right mask: Standard Bahtinov, Tri-Bahtinov, or Hyperstar/RASA variants.
Farpoint Adjustable Bahtinov Masks are the most versatile focusing tool for astrophotography — one mask fits a range of telescope sizes from 2.5" to 18". Each mask uses adjustable grommets and pegs to secure onto your dew shield or OTA, giving you a precise, reliable fit without being locked to a single telescope. Made from virtually indestructible ABS plastic and manufactured in the USA.
Universal Fit for Any Telescope
Unlike telescope-specific masks that fit one model, adjustable masks cover a range of diameters. If you own a refractor, an SCT, and a Newtonian — or plan to upgrade your scope in the future — one adjustable mask can serve them all. Simply measure the outside diameter of your dew shield or OTA and select the size range that includes your measurement.
Dew Shield or OTA Mounting
Adjustable masks work on both dew shields and OTAs. For OTA mounting without a dew shield, there must be nothing projecting from the end of your tube (like an SCT secondary holder). Mounting on the dew shield is often more convenient for astrophotography setups, especially when managing camera cords and accessories at the front of the scope. Distance from the optical train is not a critical factor — the mask works equally well at any position.
Available Sizes
- 2.5" to 4.5" — small refractors, guide scopes, ZWO Seestar S50
- 3.5" to 6.5" — mid-size refractors, small SCTs, popular with William Optics and similar OTAs
- 5.5" to 8.5" — 6" and 8" SCTs, common Celestron and Meade models
- 6.5" to 9.5" — 8" and 9.25" SCTs with dew shields
- 7.5" to 10.5" through 15" to 18" — larger SCTs, Newtonians, and Dobsonians
Who Uses Adjustable Masks
- Multi-telescope owners — one mask covers your whole fleet instead of buying a dedicated mask for each scope
- Astrophotographers building their setup — if you're likely to upgrade telescopes, an adjustable mask grows with you
- Astronomy clubs and lending libraries — adjustable masks work across many different members' telescopes, making them ideal for shared equipment programs
- Star party travelers — from dark sky preserves in the Appalachians and Great Lakes to observing sites in the Southwest deserts and California's Central Valley, one mask handles whatever scope you bring
Want the precision of an exact-fit mask? See our Telescope-Specific Bahtinov Masks. Need focus and collimation checking? See our Tri-Bahtinov Masks.
Note: Measure the outside diameter of your dew shield or OTA to select the correct size range. Watch our sizing video for help.