Reflecting Telescopes Explained

Massive Reflecting Telescope

Massive Reflecting Telescope – via wikimedia

What is a reflecting telescope?

It’s a kind of telescope, invented by Isaac Newton around 1680 to fight against the problem of chromatic aberration, that was plaguing refracting telescopes at that time.

How a reflecting telescope works

This telescope, instead of using a lens, captures light through a main mirror and a second mirror, then reflects it to the eyepiece. Basically it uses a mirror to bend the light to the point of maximal focus. It is composed by two telescope mirrors, a primary and secondary one, an eyepiece and a tube which can be made in metal, plastic or wood.

The pattern of a reflecting telescope

The advantage of these telescopes, when facing comparison with refracting, is that they have a more reasonable size and good ratio between price and quality, making them the most diffused telescope model in the world.

There are 2 basic types of reflectors:

Newtonian telescope

The way took by light in a Newtonian goes from the parabolic primary mirror toward a small secondary mirror placed in an inclined position of 45 degrees. This redirects the light to the eyepiece, placed on the side of the tube, meaning a better looking position and an easier maintenance. Using a Newtonian can be more comfortable, because of the eyepiece position, and a simpler structure, which translates in lower costs on the market.

Newtonian Reflector

Newtonian Reflector

Take a look at our selection of reflecting newtonian telescopes:
Celestron 127EQ PowerSeeker

  • 3x Barlow Lens
  • German Equatorial Mount
  • 127mm Aperture
  • 1000mm Focal Length
  • Comes with aluminum tripod and accessory tray

 

Orion 09007 SpaceProbe 130ST Equatorial Reflector
  • This 5.1 inch aperture reflector telescope gathers an ample amount of light for great views of the planets and Moon, as well as brighter galaxies, nebulas, and star clusters
  • Short 24 inch long optical tube design for easy portability and fast f/5 focal ratio for pleasing wide-field performance makes the SpaceProbe 130ST EQ a very versatile telescope the whole family can enjoy
  • Sturdy EQ-2 equatorial telescope mount and adjustable tripod allows manual slow-motion tracking of celestial objects as they appear to migrate across the night sky
  • Complete assembled telescope weighs just 27 lbs. for convenient transport
  • Includes two 1.25 inch Sirius Plossl eyepieces (25mm and 10mm), 6×30 finder scope, 1.25inch rack and pinion focuser, tripod accessory tray, collimation cap, Starry Night astronomy software, and more!

 

Orion 09798 StarBlast 4.5 Equatorial Reflector

  • A wide-field reflector telescope with enough aperture to get great views of the Moon, planets, and many bright deep-sky objects
  • A fantastic general-purpose astronomical telescope – great for the beginner to test the waters with mirror optics large enough to keep you and your family busy viewing for years to come
  • Works amazingly well with the included Expanse telescope eyepieces which yield a very wide 66 degree apparent field of view – your first look at the Andromeda galaxy will knock your socks off!
  • Fast f/4 optics and a short focal length provide a very wide field of view, making it easy to locate celestial objects without having to hunt around
  • The EQ-1 equatorial telescope mount makes tracking night-sky objects extremely easy using the included slow-motion controls.

 

Orion 10012 SkyScanner 100mm TableTop Reflector

  • An ideal entry-level reflector telescope with 100mm parabolic primary mirror optics – no plastic lenses as found in some other telescopes made for beginners
  • See hundreds of craters on the Moon, detail on Jupiter and other planets, even when viewing from relatively bright city locations
  • A tabletop telescope big enough to find and observe objects in the night sky, but small enough to easily store in a closet or display on a desk
  • Perfect reflector telescope for wide-angle, low-power viewing of the Milky Way and other deep sky objects when viewing from relatively dark skies
  • Includes two 1.25 inch telescope eyepieces: 20mm (for 20 power magnification) and 10mm (for 40 power magnification), EZ Finder II aiming device, Starry Night astronomy software, and more!

 

Dobsonian telescope

Part of the same family are the Dobsonian telescopes, invented by the amateur astronomer John Dobson in the sixties. Definitely the most used configuration between amateur visualists astronomers, thanks to his mechanical and optical configuration. It is composed of very few pieces making it easy and fast to assembly and disassembly. The structure of the instrument is composed of a metal tube, that also acts as focal length.

There are two kinds of tubes, monolithic and truss. Monolithic tube is made of a single fixed frame, while truss can be closed thanks to his collapsible configuration.

 

Take a look at our selection of Dobsonian telescopes:

Orion 10014 SkyQuest XT4.5 Classic Dobsonian

  • Compact and lightweight – a perfect Dobsonian reflector telescope for traveling or easy trips to the backyard at home
  • 4.5″ aperture and 900mm focal length provide clear views of lunar craters and plains on the Moon, planets, bright nebulas and galaxies
  • Sturdy and portable Dobsonian base and handy navigation knob allow for effortless maneuvering of the reflector optical tube
  • Collects a whopping 260% more light than a typical beginner-level 60mm refractor telescope – which means hundreds more objects will be visible through the Orion SkyQuest XT4.5 Classic Dobsonian
  • Includes two eyepieces (25mm and 10mm focal length Sirius Plossl), 6×30 finder scope, 1.25″ rack and pinion focuser, collimation cap, eyepiece rack, Starry Night astronomy software, and more!

 

Celestron S11700 Sky-Watcher 8-Inch Dobsonian

  • Collapsable Tube Design For Easy Storage and Transportation, 8″ (200 mm) Dobsonian-style Newtonian
  • 1200 mm focal length (f/6), 2″ Crayford-style focuser with 1.25″ adaptor, 4-element Plossl 25 mm and 10 mm 1.25″ eyepieces
  • 8×50 RA viewfinder, Solid rocker-mount with Teflon bearings and tension clutch

 

Meade 1005-05-03 LightBridge 10-Inch Truss Tube Dobsonian Reflector, Open Truss

  • Open truss tube design with new anti-reflection coatings on trusses and castings
  • 10-inch aperture and a focal length of 1270-millimeters
  • Focal ratio is f/5
  • Laminated base features roller bearings on the azimuth axis
  • Comes with a 1-year limited warranty

 

Catadrioptic telescope

Catadioptric telescopes are hybrid telescopes, partly refractors and partly reflectors. Invented by german astronomer Bernhard Schmidt during the thirties, these telescopes have a primary mirror at the end of the tube and a corrective lens to fix issues caused by chromatic aberration. The eyepiece and the secondary mirror are absent.

Widely used by astrophotographers to take pictures of the sky, they insert a film or a sensor on the focus of the main mirror. The most popular catadrioptic model is the Schmidt-Cassegrain telescope, which introduces a second mirror that reflects the light of the main mirror into a hole drilled in the primary itself.

Cassegrain reflector pattern

Cassegrain reflector pattern

 

Take a look at our selection of Catadioptric/Cassegrain telescopes:

Orion 10022 StarMax 90mm TableTop Maksutov-Cassegrain

  • This grab-and-go TableTop Maksutov-Cassegrain telescope provides powerful views of the Moon and bright planets such as Jupiter, Saturn, and Mars
  • Weighing just 6.5 lbs. assembled, this compact telescope and base can be taken just about anywhere to provide great views of the night sky while on road-trips, camping, or the short trip out to the backyard
  • 90mm aperture Maksutov-Cassegrain telescope gathers enough light for beautiful views of brighter deep space objects like globular clusters, nebulas, and many bright galaxies
  • Nifty tabletop base provides a stable viewing foundation you can set on any sturdy table, or even attach it to a field tripod with a 3/8″ or 1/4″-20 threaded post
  • Includes two 1.25″ eyepieces (25mm and 10mm focal lengths), EZ Finder II reflex sight for easy aiming, 90 mirror diagonal for comfortable night sky viewing, and more!

 

Celestron NexStar 5 SE

  • 5-inch Schmidt-Cassegrain telescope; StarBright XLT high transmission coatings come standard
  • StarPointer finderscope to help with alignment and accurately locating objects
  • Quick-release fork arm mount, optical tube, and accessory tray for no-tool setup
  • SkyAlign allows you to align on any three bright celestial objects, making for a fast and easy alignment process
  • Nearly 40,000-object database with 200 user-definable objects and expanded information on over 200 objects

 

Celestron 11084 Omni XLT – 127

  • High quality optics start with each lens and/or mirror being hand selected so only the finest grade of optical glass is used
  • StarBright XLT coatings provide maximized light transmission
  • 25mm multi-coated eyepiece, 20mm eye relief, 50 deg FOV
  • 1.25 star diagonal (except #31057)
  • CG-4 German Equatorial Mount with setting circles and slow motion controls to accurately locate and track sky objects

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