The Baader Universal Alan Gee II Telecompressor is a Schmidt-Cassegrain reducer and flatfield corrector, primarily designed for use with the MaxBright II and Mark V Binoviewers. Originally designed by Roland Christen of Astro-Physics, the UAG II puts the optical elements of the Alan Gee telecompressor into a regular 2" nose piece with an additional T2 (M42 x 0.75) thread for direct connection on the telescope side.
The UAG II has a variable focal length reduction factor depending on the distance between it and the eyepiece, with 0.59x at a distance of 121mm. Although designed for visual use primarily, it can also be used for photography with sensors up APS-C.
The UAG II can be attached directly to all Baader T2 star diagonals with the included Baader T2 7.5 mm Extension Tube. Although a binoviewer could mechanically also be attached to a 2" star diagonal with a Schmidt-Cassegrain, instead it is recommended to use a short adaptation with a T2-prism and Baader T Adapter for SC and MAK Telescopes BA2408160, so that the ideal focus point doesn't change too much from the original design.
The UAG II can also be installed in front of a T2 star diagonal with a T2 eyepiece clamp and – depending on the desired distance/reduction factor – a T2 extension. The UAG should be as close to the telescope as possible, so we recommend the optional Baader T Adapter for SC and MAK Telescopes BA2408160 to attach it to the telescope's SC-thread. If your telescope is equipped with a 2" ClickLock eyepiece clamp (BA2956220 for C8/C925 or BA2956233 for C11 and C14), you can also use this with the 2" nose piece of the UAG.
|Optical design||Field flattener, telecompressor
||0.59 x at 121mm backspacing
||< 50 mm
||M42 x 0.75 (T2), 2" barrel