TRI-Bahtinov Focus Mask - Celestron 52° FOV With an hour here and

With an hour here and an hour there trying to get polar aligned

you can make tension adjustments to keep the phone firmly in place

6 lb Tracking Rates Sidereal

Stepper motor with low power consumption

and weighs 11 lb

TRI-Bahtinov Focus Mask - Celestron 52° FOV With an hour here andWhat is the Tri Bahtinov? Essentially three Bahtinov masks in one, rotated over 120 degrees. It gives you three lines and three crosses to check focus and 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