160mm Bahtinov Mask / Fishbone Calibrator (158-193mm)



160mm Bahtinov Focusing Mask for Visual or Astrophotography

In Focus Results

  • Invented in 2008 by Pavel Bahtinov, these “fishbone calibrators” or “Bahtinov Mask” work by showing a very distinct visual pattern when pointed at a bright star and when you have adjusted to perfect focus.
  • Astro Dog’s Bahtinov Masks are light, won’t rust (made of light, hard plastic, CNC machined in a factory – not 3d printed from poor quality materials that will melt / degrade etc..)
  • Precisely engineered and form a lovely, clear and distinct intersecting 3 line pattern when in focus. Top quality, no need to get an expensive brand. You’ll love it.
  • This has been independently tested by the SRAA (Scenic Rim Astronomy Association) and been verified as performing the same as much more expensive brands.
  • Available in 60mm,80mm, 100mm, 120mm,140mm and 160mm, 180mm, 200mm, 230mm and even 270mm fits (see other listings).


  • Classic 160mm Fit (The three screws can be attached either via the outer diameter (small sizes from 158mm) or the inner diameter to to even fit larger sizes up to 193mm).
  • Measure your inner and outer diameter. If the sizes above fall between one of those ranges, you’ll be right! Feel free to send us a message if your unsure – we will help you!
  • Compatible with correctors and barlow lenses
  • POSTAGE – We really care. Note that we pack this in a heavy square fortified cartboard box with padding and is sent as a tracked parcel. This is NEVER shipped as a ‘letter’ or flimsy plastic bag. The fortified box also serves as storage for your mask when not in use.

Yep – I want one, how do I figure out which one I need?

Check the product gallery, one of the pictures demonstrates how to measure the mask.

Measure across the dew shield.  In this case, it comes out at about 96mm.  I should get the 80mm mask.  The 100mm version will be too much of a fit, and the 60mm mask only goes to 93mm and won’t fit. 

How to use it:

  • Attach the mask to the telescope. It is usually attached to the outer diameter, but it can be attached to the inner diameter if you wish.
  • Select a medium star with medium brightness and position it in the outer third to get optimal sharpness across your field of view.
  • Turn on your camera your camera and watch the star in “live view” mode, or “eyeball it”.
  • If not in focus, the central line is shifted. Adjust your focuser until it sits precisely between the other two lines
  • Your done! Remove the mask and start exposing your object.

Need a different sizes?  We have the following Sizes:

Some of these masks overlap in sizes.  That’s okay – simply pick the one that falls nicely into the range.

One other suggestion – pick up some parfocal rings (1.25″ / 2″).  These are rings that tighten around your eyepieces exactly where you want it – so, once you have used the bahtinov mask, all your eyepieces (even different types) will be perfectly in focus.

Additional information

Weight .5 kg
Dimensions 28 × 18 × 10 cm


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