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Newtonian Telescopes – A Simple Guide to Reflector Telescopes

Newtonian Telescopes

Reflector Telescope
Bresser telescope Messier NT-150S/750 EXOS-1/EQ4

What is a Newtonian Telescope and why are reflector telescopes so good? Read on to find out why.

A Newtonian telescope is a simple telescope design usually on an equatorial mount. Consequently, they are great for beginners and professional astronomers alike. Newtonian’s are economical compared to other types of telescope. This popular design was invented by the famous Sir Isaac Newton – Hence the name.

The telescope comes in two parts. The optical tube assembly (OTA) and the mount – The tripod bit.

The optical part of the Newtonian telescope is the same as a Dobsonian telescope. It consists of a primary parabolic mirror and a flat secondary mirror. Both in an open-ended tube. Light enters the tube and reflects off of the primary mirror. Then the secondary mirror and as a result into the eyepiece on the side.

Newtonian Telescope
Credit Skywatcher

Benefits of the Newtonian telescope

The benefit of this type of optical arrangement is the Newtonian telescopes light gathering ability. Therefore, they gather more light, which means fainter objects can be seen.

Newtonian Reflector Telescopes have a big advantage over telescopes with lenses such as refractors and Cassegrain telescopes. Mirrors are a lot cheaper to make than lenses. Plus they can be a lot bigger!

You measure Newtonian’s by the size of the primary (big) mirror. Newtonian telescope sizes range from 6 to 10 inches in diameter. They can be many times larger and less expensive to produce than telescopes with lenses.

Equatorial Mount

The second part of a Newtonian Telescope is the mount. Usually Newtonian’s come with an equatorial mount.

Equatorial or EQ mounts enable the telescope to be adjusted and follow the movement of the Earth against the sky. When set up correctly you can track stars by turning knobs and adjusters quite comfortably. However this can take some getting used to and can be quite complicated for some people. This is where Dobsonian telescopes come in with their simple up and down/ left and right hand moved mounts.

Controlling the Telescope

Newtonian telescopes can also be moved by hand. Just loosen the tension knobs etc first so you don’t force the mounts mechanisms.

The mount is usually on top of a tripod with controls at the head. In addition to this, some manufacturers have put electronic GoTo systems with motors on some Newtonian mounts. This is critical for some long exposure astro photography. But not essential for visual observing as finding objects manually by star hopping or other manual methods helps you learn the sky better. It’s also more fun!

Reflector Telescope
Celestron Astromaster 130

Resist the urge to spend lots of money on small computerised scopes. They will probably get little use. They can be expensive and difficult to set up. In addition to this, you may not see much through them apart from the brightest objects such as the Moon. Due to small optics.

Alternatively, a Newtonian is a great all-around telescope, and are also available in all telescope stores. Please browse the excellent range of Newtonian Telescopes below. Tap on the images for more details.

Some good makes to look out for are Celestron, Orion and Meade. If you require any further help just ask Virtualastro on Twitter or Facebook.

Enjoy your new telescope.

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