A Bahtinov mask with a special pattern for reflecting telescopes. It allows easier focusing and collimation control at the same time.

This mask fits on the Celestron C8 telescope. Is it based on my design for GSO RC8 and was co-developed with a owner of Celestron C8 telescope.

The special feature of the mask is that it can be stored under the cover of the telescope, which is very convenient.

The pattern of the mask is calculated according to an improved formula and brings better illumination, see the discussion on Cloudy Nights forum and the original design on GitHub.

The mask was calculated for the 2000mm focal length. It additionally has two handles to make it easier to take it out and cut offs on the side for better fitting. It still fits under the cover and can be stored that way so that you do not need additional box for it and never forget it 😉

Please note that:

• the mask is created in two parts, which are then glued. Traces of glue along the border between the parts are possible. But this does not affect the function of the mask.
• the mask is 3D-printed and the material of the mask is sensitive to heat. It starts deforming at temperatures above 50˚C. The mask should not be left in the sun, for example. Well, this should not be a problem for astrophotography 😉