The Difference Between Newtonian and Ritchey Chretien Telescopes

TPO offers a wide collection of premium reflector telescopes providing optimized views and astrophotography equipment to capture the night sky in incredible detail.

There are three types of telescopes, reflector, refractor, and catadioptric. Each telescope type has a variety of other telescopes that fall under each main type. TPO telescopes come in two types of reflectors, Newtonian and Ritchey Chretien.

What are Reflector Telescopes?

Reflector telescopes use one or more curved mirrors to reflect light captured from space and form an image, resulting in images that are free of chromatic aberration. One of the main benefits of the reflector design is that it enables a very wide diameter objective. Its wide diameter objective makes reflectors capable of being made much larger than comparable refractors. It also makes this design of reflectors easier to gather light. Remember to collimate and realign your telescope periodically to get the best views and images.

Advantages of Reflecting Telescopes

• Free of chromatic aberration
• Crisp and clean images and views
• Lower cost for reflector
• Mirrors have one reflective surface making them easier to construct

TPO telescopes come in two designs, Newtonian telescopes or Ritchey Chretien telescopes. Both offer incredible light-capturing abilities. Learn more about their differences below!

What are Ritchey Chretien Telescopes?

The Ritchey Chretien Telescope (RC) design is used in some of the most famous telescopes like Hubble, SLOAN Digital Sky Survey, and LORRI on board the New Horizons spacecraft. RC Telescopes, as they are commonly referred to, only use hyperbolic mirrors to eliminate optical errors like coma and chromatic aberrations off-axis while producing the flattest focal plane possible without lenses. Since they only use two reflective surfaces, Ritchey Chretiens are also very efficient with light compared to most other telescope systems that use 4, 6, or event more surfaces that will reduce the amount of light hitting the focal plane.

The lack of refractive lens elements allows this telescope design to detect wavelengths broader than the visual spectrum making them very useful for measurements in the ultraviolet (UV), near-infrared (NIR), and infrared (IR) wavelengths. RC telescopes are also very modular, field flatteners are available for expanding the corrected image circle, reducers can be integrated for faster focal ratios, and barlows can be used for longer focal lengths. With all these properties within one telescope, it’s easy to see why RCs are extremely desirable among researchers and advanced astrophotographers.

Advantages of Ritchey Chretien Telescopes

Advantages:

• Produce high quality images with little distortion
• Flat field of view providing sharper objects to the edges of the image
• Shorter exposure times because of faster focal ratios
• Used for research and advanced imagers

What are Newtonian Telescopes?

Newtonian telescopes, invented by Sir Isaac Newton, are often less expensive than other astronomy optic designs that have the same size aperture. They provide wide field views due to their short focal length and are very efficient with light gathering because of their fast focal ratios. Newtonians, as they are commonly called, are generally much more portable than the larger Dobsonian telescopes, which have the same optics design. They also make for fantastic imaging telescopes because their fast focal ratios and because they are free of chromatic aberrations. Not only are these telescopes used for astrophotography, they are also great for visual astronomers as well.

Advantages of Newtonian Telescopes

Advantages:

• Yield large aperture for a lower cost
• Very wide field of view making them excellent for imaging and observing deep sky objects
• Cooldown time is short because they usually have an open tube
• They almost always have a short focal length which means fast focal ratios

Whether you decide to purchase a Newtonian or Ritchey Chretien, TPO telescopes provide great value as astrophotography or visual scopes.

What is your preferred telescope to use, and for what purpose? Let us know below! Clear skies!