Faroint Tri-Bahtinov Focus Mask, FP410RT - fits Celestron 8″ RASA. — Open-Box, 28% Off

Farpoint Bahtinov Masks are one of the best tools for manually focusing your telescope available to astrophotographers. 

Tri-Bahtinov is 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. 

In 2005, Pavel Bahtinov, a Russian amateur telescope maker and astronomer detailed a new way to focus your DSLR, CMOS or CCD camera for astrophotography by adding a mask that matches the diameter of your telescope.

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

How it Works 

These mask will work equally as well on the end of a scope or on the end of a dew shield on top of that the mask itself does not need to be perfected centered on the scope this is due to the angle of the slits themselves. Select a bright star as your guiding object. Place the Bahtinov focusing mask on your telescope's lens and secure it into place using the rubber tabs. The slits in the mask design create a set of diffraction spikes on the star that will assist in the accuracy of your focus. It will appear on your screen or computer as an "X" with a line through the center (when in focus). 

The diffraction spike pattern from a bright star using a Bahtinov mask As you adjust the focuser of your telescope, the central spike will move in and out of the X-pattern. If you are using capture software be sure to compensate for the lag time between exposures on the screen, typically 5 seconds. The same process applies using Live view display on your DSLR camera.

Who We are We at Farpoint Astro are a California based manufacturer of astrophotography filters, scopes, and tools.