Astrozap Focusing cap - Bahtinov focusing mask - Celestron 5" SCT or Astro-Tech AT115EDT


Availability: More on the way

This Astrozap Bahtinov mask focusing cap fits Celestron 5" SCT or Meade ETX125 Maksutov-Cassegrains, the Astro-Tech AT115EDT apo refractor, or any scope with an optical tube outer diameter between 136mm and 146mm . . .
Our Product #: FC125AZ
Astrozap Product #: AZ-405

Product Description

This Astrozap focusing cap with built-in Bahtinov focusing mask will fit the Celestron C5 5" SCT or 5" Meade ETX125 Maksutov-Cassegrain, the Astro-Tech AT115EDT apo refractor, or any scope with an optical tube or lens shade measuring between approximately 136mm (5.35") and 146mm (5.75") 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:
Bought this focusing mask from Astronomics a few months back. It was for a AT115EDT that I had purchased on CN. It is very convenient but does have a few drawbacks: It is not 100% dustproof. Some air can get around between the outer cover and the inner swivel. I suggest not leaving this on too long but it can be good for a preparing for an observing session (a few hours) and would probably be okay at a star party. I may modify with some felt so that it fits tighter and blocks more light for taking darks. The rotating mask can be hard to turn if the overall cover is pushed all the way in so be prepared to have it on a little loose loose. The screws are nylon so they do not mar. I'm very pleased with the construction. The aluminum is thick enough and the coating is good. Overall a good product and does what is expected. (Posted on 1/1/2019)
Review by:
Works well with my AT115. Easy to focus and also close up for taking darks. Its not sealed so I do not recommend it as a replacement for the real dustcap. (Posted on 12/31/2018)
Review by:
I use this astrocap with my AT115edt. It fits perfectly and works well as a focusing mask. It can also be used as a dust cap for taking darks or brief storage. Its not sealed so I do not leave it on the scope for extended storage, the factory dust cap is better for this. (Posted on 12/31/2018)
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