ANATOMY OF A CATADIOPTRIC

1 Visual back

The hole at the back of the telescope is threaded, meaning that a variety of accessories can be attached, including an eyepiece. A camera can also be added for astrophotography using adapters.

2 Spherical primary mirror

The catadioptric’s primary mirror is made to a spherical curve cross-section. The aberrations produced by this mirror can easily be corrected to give a good image.

3 Cooling fan

In larger MaksutovCassegrains, one or more cooling fans are built into the body of the instrument to get the glass to cool down faster. This stabilises and improves images.

4 Secondary mirror

The secondary mirror can be found on the reverse of the meniscus lens in MaksutovCassegrain telescopes. As in Schmidt-Cassegrains, this mirror reflects light from the primary mirror back down the tube to the focuser.

5 Meniscus lens

This is the lens found at the front of the telescope in Maksutov-Cassegrain instruments. This alters the light rays to compensate for any aberrations that are introduced by the spherical primary mirror.