Cassegrain Telescopes

Cassegrain Telescopes are made with a combination of a primary concave mirror and a secondary convex mirror. Their design consists of these two mirrors so that the tube can have a larger aperture while staying to a shorter length front to back. Make your selection from a wide array of high-quality Cassegrain Telescopes from name brands such as Meade, Celestron, Takahashi and many more.

The Cassegrain is a type of reflecting telescope which employs a combination of a primary concave mirror and a secondary convex mirror into its design. In the classic Cassegrain telescope a parabolic primary mirror has a hole placed in its center.  While this may seem like a very strange thing to do, the incoming electromagnetic waves are actually captured by the parabolic mirror’s edges and re-directed to the hyperbolic secondary mirror where they converge.  The light (or wave) is then refocused back towards the hole where it converges to a focal point – the eyepiece.  This “folding” technique makes for a very compact design which delivers longer focal lengths and permits higher magnification factors. It emerged over time as one of the most popular designs in the world because it offered major improvements over original refractor designs. Their sharp, high contrast images on any subject make the Schmidt-Cassegrain Telescope (SCT), Maksutov-Cassegrain (spot) Telescope (Mak), or a Maksutov-Cassegrain (sub-aperture, like the Vixen VMC) a good choice for the intermediate to more experienced observer.

Simple Cassegrain light path.

Maksutov-spot-Cassegrain light path.

Maksutov-Cassegrain-sub-aperture light path.

Advantages: Using a mirror at the back and then again towards the front of the telescope folds the light path, making the tubes shorter and easier to transport from place to place. For example, an 8-inch Cassegrain telescope can be around 45 cm long which is a third of the length of an 8-inch Dobsonian telescope. They are great for both deep sky and planetary observing and imaging. Most of these telescopes come with computerized GoTo functionality or motor-driven tracking which is great if you're looking for a telescope that can do it all. And lastly, they are nearly maintenance free, only requiring collimation from time to time. 

Disadvantages: Motorized tracking and GoTo functionality are great features to have for your telescope but they have an added cost. This typically makes them more expensive than other similar telescopes like Newtonian Telescopes. The telescope itself is compact and small but the mounts are normally a bit on the heavy side making them together  somewhat more difficult to transport.