Baader UAG II telecompressor for SC telescopes

Baader UAG II telecompressor for SC telescopes

DESCRIPTION
The Baader Universal Alan Gee II (UAG II) is a telecompressor and field flattener designed for Schmidt-Cassegrain telescopes. It contains the optical elements of the Alan Gee Mark II (designed by Roland Christen) mounted inside a 2" nosepiece, with a T-2 thread on the telescope side. It can also be used for visual observation with EdgeHD telescopes.

The UAG II offers a variable focal reduction factor ranging from 0.59 to 0.35 depending on the optical distance. When used at a 121 mm distance from the eyepiece or sensor, it provides a 0.59× reduction. However, if the optical train increases the telescope’s backfocus (e.g., with a star diagonal or long optical path), the telescope’s effective focal length changes, and so does the actual reduction factor. This makes it impossible to give a single universal value, but the increase in field of view is clearly visible.

The UAG II is especially optimized for binocular viewing. It is directly compatible with Baader MaxBright II and Mark V binoviewers via their T-2 threads, as well as Baader T-2 star diagonals. A 7.5 mm T-2 extension tube (#1508155) is included for proper spacing in recommended setups. When used with a C8, Mark V binoviewer, and Baader 35 mm ED eyepieces, it delivers a field of view of about 1.2° (72 arcminutes) — equivalent to a 2" 40 mm eyepiece.

For monocular use, the UAG II can be mounted in front of a T-2 star diagonal using a T-2 eyepiece holder and extension tubes to achieve the desired reduction factor. To place the reducer closer to the telescope’s SC thread, Baader offers adapters such as the Rotatable Adapter 2"/SCTi to T-2a (#2408160) or the Adapter 2"/SCTa to T-2i (#2958242), which replaces the standard 2" nosepiece on Baader diagonals. This keeps the setup compact and limits the extension of the telescope’s focal length.

The UAG II can also be used for imaging with camera sensors up to APS-C size, maintaining a 121 mm backfocus. However, Baader recommends using the original Alan Gee (#2454400) for optimized astrophotography, as it was designed to be inserted inside the central baffle of SC telescopes.

TECHNICAL SHEET

• SKU: 2454405

• EAN: 4047825044303

• Brand: Baader Planetarium

• Net weight: 0.13 kg

• Optical design: Telecompressor and field flattener

• Optical coating: Multi-Coated (MC)

• Optical length: < 50 mm

• Compatible telescopes: Schmidt-Cassegrain (including EdgeHD)

• Mounting: 2" nosepiece with T-2 thread on telescope side

• Reduction factor: Variable from 0.59 to 0.35

• Recommended distance for 0.59×: 121 mm

• Visual use: Binocular (MaxBright II, Mark V), monocular possible

• Imaging use: Up to APS-C sensor size

• Included accessory: T-2 extension tube 7.5 mm (#1508155)