The main application is surely photography. Here, the focal length can be reduced down to 35% of its original value. If you, for instance, have a classical 200/2000mm SC telescope, you can turn it into a fast system with a focal length of 700mm. We recommend using this extreme factor only in conjunction with small CCD cameras. With DSLR cameras similar sized CCDs, a reduction down to 60% of the original focal length has proven best.

Find a photo of M31, made with a C8 and the Alan Gee, in the "user reports" folder.

Telescopes without main mirror focusing are limited in their ability of focal reduction. The bigger the distance between AlanGee and sensor (and therefore the reduction factor) is, the further the focal plane moves into the telescope. At a certain point, focusing is not possible any more. This is also the reason why the Alan Gee does not work with Newtonian telescopes.

The Alan Gee can also be used for visual observation.
The image remains sharp and contrasty. Especially telescopes with long focal lengths are worth a try.

How does the variable focal reduction work?
The Alan Geeer Alan Gee consists of a compressor lens system and a couple of spacers. The bigger the distance between reducer and sensor, the bigger is the reduction factor. The maximum useful reduction factor is reached when the image becomes vignetted or cannot be focused any more.

We recommend to experiment with several spacer combinations in order to find out the best reduction factor for your telescope / camera combination. Then, the configuration can be noted for later reference.