Baader Planetarium Alan Gee Mark II Telecompressor

This telecompressor is specifically designed for Schmidt-Cassegrain telescopes (SCTs). It is optimized to work with f/10 systems, reducing them to f/5.9, so it may not provide the intended results on other optical designs.

Yes, it is designed for both. It provides a wider, flatter field of view that is excellent for deep-sky imaging, while also serving as a high-contrast tool for visual observation, particularly when paired with binocular viewers.

By reducing your focal ratio from f/10 to f/5.9, this accessory significantly widens your field of view. This allows you to fit larger celestial objects into the frame or eyepiece that would otherwise be cropped out at the native focal length.

Installation is straightforward, but it requires placing the lens elements deep within the telescope's baffle tube. The kit includes the necessary lens cell and spacer tubes to ensure proper positioning for your specific optical train.

The 35mm clear aperture is designed to maximize the field size for standard 1.25-inch eyepieces and most common imaging sensors. While it is quite large, heavy vignetting can still occur if you are using very large format sensors or wide-field 2-inch eyepieces.

The Alan Gee Mark II is unique because it is specifically optimized for use with binocular viewers, allowing you to achieve focus that standard reducers often cannot accommodate. Its air-spaced doublet design also prioritizes high-contrast, sharp imagery across the entire field.