80mm Bahtinov Pinpoint Focusing Mask / Fishbone Calibrator Mask (78-113mm)

An essential tool for Astrophotography and those determined to get the best view possible

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).

Details:

• Classic Fit (The three screws can be attached either via the outer diameter or the inner diameter.

• 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?

Measure across the dew shield.  In this case, it comes out at about 91mm.  I could get either the 60mm mask (which goes up to 93mm), or a 80mm mask (which falls between 78-113mm).  The 100mm version is unsuitable (as it starts at 98mm).  The most suitable is the 80mm mask.

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:

• 60mm Mask (fits 58-93mm diameter)
• 80mm Mask (fits 78-113mm diameter)
• 100mm Mask (fits 98-133mm diameter)
• 120mm Mask (fits 118-153mm diameter)
• 140mm Mask (fits 138-173mm diameter)
• 160mm Mask (fits 158-193mm diameter)
• 180mm Mask (fits 178-213mm diameter)
• 200mm Mask (fits 198-233mm diameter)
• 230mm Mask (fits 228-263mm diameter)
• 270mm Mask (fits 268-303mm diameter)

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. 

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