Being able to easily port your telescope around with you everywhere you go is ideal for many scientists and astronomy-enthusiasts. The Cassegrain telescope is one of the best in terms of portability. Between its compact design and excellent optical quality, the Cassegrain telescope is a great all-purpose telescope.
The Cassegrain scope’s portability is due to its genius design, it uses both a concave mirror and a convex mirror. The primary concave mirror is placed at the back of the tube while the secondary convex is placed at the front.
At the center of the primary mirror is a hole. This hole allows for the electromagnetic waves to be captured by the primary mirror’s edges and redirected to the secondary mirror. It is at the secondary mirror that the waves converge and are then refocused to the back of the primary mirror.
This design places the focal point behind the primary mirror, and the secondary mirror adds a telephoto effect, which results in a longer focal length. Together, these two mirrors cause the optical path to fold back onto itself. This folding makes the telescope much more compact and small.
Cassegrain scopes are great options for more serious stargazers. They are great for planetary and sky viewing and astrophotography, but they can cost more than other amateur-favorites such as the Newtonian telescope.
Above is a basic description of a Cassegrain telescope, but there many variants to this model. Here are some modern Cassegrain telescope variations:
- Classic Cassegrain: The classic Cassegrain scope uses a parabolic primary mirror and a hyperbolic secondary mirror.
- Ritchey-Chretien: The Ritchey-Chretien is a specialized Cassegrain that uses two hyperbolic mirrors. It is best for wide field and photographic observations.
- Dall-Kirkham: The Dall-Kirkham is a specialized Cassegrain that uses a concave elliptical primary mirror and a convex spherical mirror.
- Catadioptric Cassegrains: These Cassegrain telescopes use both mirrors and lenses. Schmidt-Cassegrain, Maksutov-Cassegrain, Argunov-Cassegrain, and Klevtsov-Cassegrain are all examples of Catadioptric Cassegrain scopes.
Of these variants, the Ritchey-Chretien telescope is probably the most effective and useful for stargazing purposes. The Ritchey-Chretien uses two hyperbolic mirrors. This design causes the scope to be free of coma and spherical aberration on a flat focal plane. This fact makes the scope ideal for a wide field and photographic observations. The most known Ritchey-Chretien scope is the Hubble Space telescope.