Astrozap Focusing cap with built-in Bahtinov focusing mask for 8" Schmidt-Cassegrains and similar scopes


Availability: In stock

This Astrozap Bahtinov mask focusing cap fits most 8" Schmidt-Cassegrains, or any scope with an optical tube outer diameter between 216mm and 231mm . . .
Our Product #: FC8AZ
Astrozap Product #: AZ-408

Product Description

This Astrozap focusing cap with built-in Bahtinov focusing mask will fit most 8" Schmidt-Cassegrains, or any scope with an optical tube or lens shade measuring between approximately 216mm (8.5") and 231mm (9.1") in outer diameter. Check your optical tube diameter for certain before ordering.

The inside of the focusing cap is lined with soft foam to protect the finish on your scope or lens shade. Three nylon thumbscrews tighten onto your scope's front cell or lens shade to hold the focusing cap in place and allow the cap to fit the above range of scope diameters. When not used for focusing, the Bahtinov wheel can be closed as shown below allowing the focusing cap to be used as a dust cap for your scope.

The feature image below will show you a star's appearance in a Takahashi Epsilon 180 reflector as seen through the Bahtinov Mask. The difference in the focuser position between the almost-in-focus images and the sharply focused image shown below is very small, only a few tenths of a millimeter, showing the sensitivity of the Bahtinov focusing method.

Tech Details

Warranty 1 year


Review by:
It's hard to focus on stars accurately for deep sky astrophotography. The littlest bit off could kill hours of work. Definitely worth the investment! (Posted on 10/17/2019)
Review by:
This is one weird device and it does the job of getting you to an accurate focus. I made a special focusing system starting with a Meade zero image shift focuser and some custom electronics and when I tested it on this mask, it worked each time. I just wish the slots were 120 degrees apart to give more resolution but that might not be possible by Bahtinov's technique. If you spent a fortune on your scope, you should seriously consider this tool. By the way, I use it for visual astronomy so don't think it's only for astro photography. (Posted on 8/4/2017)
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