Refracting Telescopes: Introduction
Given the mysterious beauty of the endless cosmos, there’s no doubt that telescopes are among the most fascinating instruments in the field of science. Telescopes are essential devices that have enabled the study of the universe by providing magnified images of distant objects and structures.
Interestingly, telescopes have undergone significant transformations throughout the centuries. The first type of telescope – the refracting telescope – was invented in the 17th century, with spectacle-maker Hans Lippershey being credited as the inventor of the telescope. We should note that it was Galileo Galilei who improved the magnification of the telescope and pointed it towards the skies, and Johannes Kepler made significant advancements in the field of optics. Over the centuries, notable scientists such as Christiaan Huygens, Isaac Newton, Chester Moore Hall, and William Herschel contributed to improving telescope usability and power.
Now there’s a wide variety of optical models that support both terrestrial and astronomical use. With the advancements in technology, powerful and computerized telescopes (including radio, infrared, and gamma-ray units) have enhanced the study of distant objects, such as nebulas, novae, and asteroids, by their emission or reflection of electromagnetic radiation. Amateur astronomy is also on the rise, with optics industry leaders like Celestron, Meade, Orion, and Vixen offering countless products for stargazing.
How to Choose a Refracting Telescope?
From looking at the stars at night to observing distant objects on land, telescopes are fascinating inventions in the field of science. There’s a wide range of magnifying units classified by the tasks they perform, such as theodolites, astrographs, and solar telescopes – with optical refracting telescopes for amateur astronomy being among the most popular instruments on the market. There are three main factors users should consider when choosing a telescope that can enhance the study of the heavens:
- Total cost
Requirements: With a variety of products on the market, choosing a telescope can be tedious. First of all, users should decide what objects they want to see and where they’ll be viewing them. Note that telescopes for amateur astronomy are highly popular, which can cover supernova, comet, and planets searches, as well as solar and lunar research. There are three types of optical telescopes that are ideal for astronomical use: 1) refracting telescopes that use lenses to bring light to a focal point; 2) reflecting telescopes that use mirrors to form an image; 3) catadioptric telescopes that employ both mirrors and lenses.
The refracting telescope, in particular, is the first type of telescope ever created. Such units consist of long tubes with eyepieces located at the back. Just like other optical telescopes, refracting telescopes gather light from the visible part of the electromagnetic spectrum to increase both the size and the brightness of distant objects. As light enters the tube, rays are directed through a lens and then focused on a single point to magnify objects. Refracting telescopes are easy to use and maintain; they are ideal for high-contrast viewing and imaging of double stars, planets, and deep-sky objects.
Specifications: Aperture and magnification are the two main specifications that should determine purchasing choices. Note that aperture refers to the diameter of the telescope’s main optical part through which light passes, as well as its resolving power. High levels of light-gathering can guarantee bright images, while high resolution can provide sharp images. Note that in refractor telescopes, different wavelengths end at different rates, which can cause chromatic aberration. Nevertheless, advances in technology have led to the development of apochromatic refractor telescopes that solve the problems of chromatic aberration (via extra-low dispersion or fluoride gas), which makes these units ideal for astroimaging.
Magnification is another vital characteristic to consider. Note that excess magnification can lead to blurry images, so the maximum useful magnification should be 50 times the unit’s aperture in inches or twice of its aperture in millimeters. To provide an example, a high-quality 4-inches telescope with magnification rates of 200X is considered a sufficient refracting unit. Note that low powers are ideal for viewing deep-sky objects (e.g., galaxies), while medium-high powers are ideal for observing bright objects (e.g., planets). For instance, a high-quality 80 mm refractor can be perfect for viewing the Moon, the Sun, and the planets in our solar system.
Total cost: Telescopes come in all shapes and sizes, with aperture and optical quality being among the most crucial factors to determine costs. The bigger the aperture, the better the image is. Units with a small aperture (e.g., 50-70 mm achromatic refractor) are affordable and ideal for amateur viewing. On the other hand, a high aperture (e.g., above eight inches) can provide impressive views of deep-sky objects, such as galaxies and star clusters. The materials used to make telescopes are also essential – sturdy material and waterproof exterior coating are a must.
Accessories, such as stands, mounts, focusers, camera adapters, and carry bags, can add more to the final cost. Note that a stand that’s both stable and light is essential to ensure accuracy and comfort. Mounts (altazimuth, equatorial, or motorized), on the other hand, allow users to align the unit and track celestial objects.
Best Refracting Telescopes
With a variety of products and competitors on the market, choosing a telescope can be a daunting endeavor. Based on different specifications and user reviews, here’s a list of the best refracting telescopes suitable for astronomical use, nature studies, and bird-watching.
Celestron 21034 Ambassador 80 mm Refractor Telescope
- Aperture: 80 mm
Celestron 21034 Ambassador 80 mm Refractor Telescope is an elegant unit with a brass optical tube, a wooden altazimuth mount with mahogany finish, and a vintage design. With fully coated optics and an 80 mm aperture, this unit is suitable for both terrestrial and astronomical use. Note that the tripod this unit comes with can be adjusted, which makes it suitable for both children and adults. Celestron 21034 Ambassador 80 mm Refractor Telescope is a beautiful tool and a chic present choice for anyone who wants to take a peek beyond the horizon.
Sky-Watcher ProED 80 mm Doublet APO Refractor Telescope
- Aperture: 80 mm
Sky-Watcher ProED 80 mm Doublet APO Refractor Telescope is one of the best refractor telescopes on the market. It comes with a doublet apochromatic lens system, extra-low dispersion Schott glass, and photon anti-rejection metallic high-transmission coatings to reduce chromatic aberrations and improve contrast, color rendition, and brightness. Note that the telescope has an 80 mm aperture and a 600 mm focal length. With a two-speed Crayford-style focuser, Sky-Watcher ProED 80 mm Doublet APO Refractor Telescope is ideal for both professional and amateur stargazers.
Orion 10013 GoScope 80 mm TableTop Refractor Telescope
- Aperture: 80 mm
Orion 10013 GoScope 80 mm TableTop Refractor Telescope is a portable tabletop unit that comes with an 80 mm aperture and two 1.25-inch eyepieces (20 mm and 10 mm) to enable terrestrial and astronomical viewing. Note that because of its lightweight design, this unit can be easily mounted on a tripod with a 3/8 inch or ¼-20 threaded post. With a variety of settings, Orion 10013 GoScope 80 mm TableTop Refractor Telescope is a wonderful refracting instrument.
Gskyer AZ70400 Telescope
- Aperture: 70 mm
Gskyer AZ70400 Telescope is a sophisticated telescope kit that comes with two replaceable eyepieces (16X and 40X), a 5X24 finderscope with a mounting bracket, and a carry bag. The unit is made of high-quality optics covered in a special green film and an aluminum base. With a 70 mm aperture and a 400 mm focal length, Gskyer AZ70400 Telescope is ideal for beginners, children, and outdoor enthusiasts.
Gskyer 60 mm AZ Refractor
- Aperture: 60 mm
Gskyer 60 mm AZ Refractor is another popular telescope kit, which is ideal for observing animals, studying scenery, and viewing the night sky. The unit has a 60 mm aperture and a 350 mm focal length; its maximum magnification is 105X. Note that this telescope features a 1.5X erecting eyepiece and a 3X Barlow lens. With a variety of accessories and its portable design, Gskyer 60 mm AZ Refractor is a great tool for beginners and astronomy lovers.
Celestron PowerSeeker 80EQ Telescope
- Aperture: 80 mm
Celestron PowerSeeker 80EQ Telescope is a wonderful refracting telescope with an aperture of 80 mm and a focal length of 900 mm. With its high-quality German equatorial mount, the unit can enhance both astronomical and terrestrial use. Additionally, the telescope features two eyepieces (20 mm and 4 mm), an erect image diagonal, a finderscope, an aluminum tripod, an accessory tray, and a 3X Barlow lens. One of the many extra features it comes with is BONUS Starry Night Basic Edition astronomy software with information on 36,000 celestial objects and printable sky maps. Celestron PowerSeeker 80EQ Telescope is simply ideal for navigating the mysteries of the night sky.
Celestron 21061 AstroMaster 70AZ
- Aperture: 70 mm
Celestron 21061 AstroMaster 70AZ is another product that comes with an altazimuth mount, two eyepieces (10 mm and 20 mm), and an erect image diagonal. Note that the unit is easy to set up and use. With coated glass optics, a permanently mounted StarPointed finderscope, and a sturdy stand, Celestron 21061 AstroMaster 70AZ is ideal for viewing, tracking, and centering celestial objects.
Orion 9534 ED80T CF Triplet Apochromatic Refractor Telescope
- Aperture: 80 mm
Orion 9534 ED80T CF Triplet Apochromatic Refractor Telescope is a powerful triple apochromatic refractor that features an 80 mm aperture and lightweight design. Its Crayford focuser enhances sharp wild field images, with the smaller fine focus knob being able to adjust the focus level at a rate of 11:1. Note that Orion 9534 ED80T CF Triplet Apochromatic Refractor Telescope excels in visual applications, which makes it ideal for astroimaging.
Orion 9024 AstroView 90 mm Equatorial Refractor Telescope
- Aperture: 90 mm
Orion 9024 AstroView 90 mm Equatorial Refractor Telescope is a sophisticated refracting telescope. It has a 90 mm aperture, a 910 mm focal length, an equatorial mount, two Sirius Plossl 1.25-inch eyepieces (25 mm and 10 mm), and a 6X30 finderscope. Additionally, the unit comes with a smooth-adjusting 1.25-inch rack and pinion focuser and a 90-degree mirror diagonal for comfortable nighttime performance, as well as Starry Night astronomy software. With numerous advanced features, Orion 9024 AstroView 90 mm Equatorial Refractor Telescope is powerful, practical, and affordable all at the same time.
Meade Instruments 209006 Infinity 102 mm AZ Refractor Telescope
- Aperture: 102 mm
Meade Instruments 209006 Infinity 102mm AZ Refractor Telescope is a powerful model that comes with a red-dot viewfinder, a focal length of 600 mm, and an aperture of 102 mm. The unit is equipped with low (26 mm), medium (9 mm), and high (6.3 mm) magnification eyepieces and a 2X Barlow lens to double the magnifying power of each eyepiece. Note that there’s an altazimuth mount included, which is equipped with slow-motion controls to track celestial objects. Meade Instruments 209006 Infinity 102 mm AZ Refractor Telescope is a great choice for anyone interested in astronomy.
Celestron 60 LCM Computerized Refractor Telescope
- Aperture: 60 mm
Celestron 60 LCM Computerized Refractor Telescope is a computerized refractor with an aperture of 60 mm and a focal length of 700 mm. With its GoTo mount, the unit can help users automatically locate celestial objects. The telescope also comes with high and low-power eyepieces, an erect image diagonal, a red-dot viewfinder, and a computerized altazimuth mount with a database of more than 4,000 celestial objects. Celestron 60 LCM Computerized Refractor Telescope is ideal for camping, parties, and backyard observations.
Taking Care of a Telescope
Given the fact that telescopes are invaluable instruments in the field of science (for both terrestrial and astronomical use), there’s no surprise that buying a telescope can be a rewarding investment. Yet, proper use and maintenance are essential to guarantee a long life.
- One of the main requirements is to handle telescopes with care. Users should always consult instruction manuals regarding assembling and use.
- Transporting telescopes is also essential. Therefore, a comfortable and reliable carry bag is a must-have accessory.
- As dust, heat, and moisture can damage telescopes, proper storage is also paramount. Optics should be covered when not in use; for instance, a dust cap for the tube and a plastic bag for the focuser can prevent damage and incidents.
- Cleaning telescopes (including eyepieces, filters, and main optics) can be challenging. Note that cleaning the optics of a telescope is required only if the unit is covered with excessive dirt or dust, as frequent cleaning can only damage the unit. Users should never touch lenses or mirrors directly with their hands but use compressed gas or air instead. Surgical cotton, lens tissues, and solution can help be utilized as well.
- Users should avoid dissembling their units. In fact, the design of a refracting telescope consists of a closed tube, so it is unlikely that dirt will be deposited on the telescope’s primary lens.
- Last but not least, any user should practice using their new telescope during the day to familiarize themselves with the unit and its features. Never look directly at the sun to prevent severe eye damage! Additionally, users should invest some time in studying maps of the night sky to familiarize themselves with all the objects and phenomena in the cosmos in order to know what they are viewing.
Refracting Telescopes: Conclusion
Telescopes are invaluable instruments in the field of science. With a variety of features and competitors on the market, choosing a telescope can be tedious. Users should consider three major factors before purchasing a telescope: requirements (what objects they want to see and where they’ll be observing them), specifications (e.g., aperture, magnification, lenses, stands), and total costs (including accessories, such as trays and carry bags). Note that units with high aperture are suitable for high-contrast viewing and imaging of deep-sky objects, while units with low aperture are ideal for observing bright celestial objects.
Refracting telescopes, in particular, are the first type of optical telescopes ever invented. These instruments are suitable for both terrestrial and astronomical use. As stated above, refractor units consist of long tubes with eyepieces located at the back and use lenses to bring light to a focal point to magnify objects. Although different wavelengths can end at different rates, advanced apochromatic refractor telescopes eliminate the problems of chromatic aberration. Computerized models, on the other hand, are ideal for beginners with little knowledge about the night sky as they allow automatic tracking of celestial objects and easy use. Although refractor telescopes are relatively easy to maintain, users should take proper care of their equipment to ensure both proper use and long life.