Farpoint Tri-Bahtinov Focusing Mask - Celestron

The Tri-Bahtinov Mask is an advanced version of the Bahtinov mask that allows for even more precise adjustments and can also be used as a collimation tool.

It does NOT fit with the Hyperstar or Fastar camera installed. But if you look carefully, you will see a slit that goes almost all the way across one side. Just complete that slit and you can flex (twist) the mask to open it up to get around the camera.

Tri-Bahtinov Focus and Collimation Mask is an ingenious new way to easily focus a telescope. Pavel Bahtinov, a Russian amateur telescope maker and astronomer, created this simple, very intuitive method and the device has universally been named after him: The Bahtinov Mask.

The Bahtinov will produce Cross-shaped stars, with one clear line that moves along the cross as you focus. When the line is centered on the cross, you should have achieved perfect focus.

What is the Tri-Bahtinov?

It essentially three Bahtinov masks in one, rotated over 120 degrees. It gives you three lines and three crosses to check collimation, along three axis simultaneously.

In addition to focusing, the tri-Bahtinov so also indicates collimation status along three axis.

This is interesting for e.g. Schmidt-Cassegrain telescopes, where the collimation is done by push-pull screws of the secondary mirror along three axis.

When you position the tri-Bahtinov alongside these axis, it will give you insight not only per axis of the focus but also how different these focus points are for each axis.

Bahtinov mask is a less expensive method of getting focus on objects in the night sky compared to a standard motor focuser.

With the right mask and setup, it’s easy to get crystal clear focus on a star in less than 90 seconds.