TRI-Bahtinov Focus Mask - Celestron Guidescope 5") Inside Dimensions 432mm x

5") Inside Dimensions 432mm x 273mm x 273mm (17" x 10

Easy dovetail connection

178 LCD: Red backlit 4 Line LCD CPU: STMicro ARM 32-bit Cortex™-M3 CPU Software and Firmware: Fully upgradable RS-232 Port: PC connectable for software/firmware upgrades

more true field

A review of calibration frames     85

TRI-Bahtinov Focus Mask - Celestron Guidescope 5") Inside Dimensions 432mm xWhat 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