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Test Bench: Telescopes
Stargazing can be easy. We trial the home instruments that open up the night sky
The night sky has been a source of fascination for thousands of years and studying it is a surprisingly approachable hobby. Basic “backyard astronomy” can involve merely a pair of good binoculars, but if you are at all serious then a proper telescope is a must.
Be wary of cheap gadget-shop offers. Some may look like telescopes but they are more suited to picking out yachts from the harbourside than relishing Saturn’s rings, and nothing kills an interest in the stars faster than a wobbly telescope with poor optics.
A common misconception is the benefit of high magnification. A good telescope is about collecting light, not merely magnifying it, and this necessitates a large-aperture lens or mirror. Without one, your telescope may magnify an image 400 times but it will be too dim to see.
There are three main categories of telescope: the refractor, the reflector and hybrid designs that mix the two. The refractor is what you probably think of when you hear the world telescope – a tube with a lens at one end that gathers light from the stars, and an eyepiece at the other to magnify it. With a reflector design, light is gathered by a concave mirror at the bottom of the tube and then reflected to a second mirror at the top, which reflects it to an eyepiece.
Hybrid telescopes combine mirrors with lenses to enhance the image and reduce distortion. Within these categories there are many variations, but don’t worry if you don’t know your Dobsonian from your Schmidt-Cassegrain.
Which is best? Reflector models are generally cheaper than refractors and offer the best value for novices. Because they tend to have a wider aperture they provide a brighter image than a similarly priced refractor. On the downside, their more basic design has its limitations. Stars at the edge of the image can often appear distorted, with a comet-like trail known as a coma appearing. Most modern reflectors include “coma correction” technology to reduce this.
Enthusiasts are more likely to opt for a refractor. They are pricier but well suited to looking at planets, though they can create faint fringes of colour around brighter space objects such as stars.
The main tube of a telescope is not the whole story. Many packages include a tripod and one or more eyepieces that provide different degrees of magnification. A stable mount is vital, as even slight movements will be magnified intolerably.
There are two basic types: the simpler altazimuth mount enables a telescope to be moved vertically or horizontally; alternatively, a fancy equatorial mount compensates for slight movements caused by the Earth’s spin to give a steadier view and these sometimes employ a small motor to keep objects squarely in view. This is helpful for astro-photographers who attach an SLR (single-lens reflex) camera or a webcam to their telescope to shoot the heavens.
Attaching a computer-aided positioning system to your mount will help you easily locate the planets and deep-sky objects outside our solar system such as star clusters. The easiest is known as a GoTo system; one is featured on the Celestron scope tested here. This sort of point-and-shoot astronomy is ideal for newcomers.
Generally speaking, bigger telescopes are better, but they are more complex to handle and cumbersome to pack up, especially if you want to flee the light pollution of the city for the weekend.
Research supplied by Astronomy Now magazine
Reviews adapted by Stuart Andrews
Prices include Vat and delivery
JARGON BUSTER
GPS (Global positioning system) Satellite-based technology that enables a gadget to plot its location. More commonly employed by in-car sat navs
GoTo mount Tool that can be added to some conventional telescope mounts to locate stars and planets automatically, using GPS technology
Equatorial mount Telescope mount that compensates for slight movements caused by the Earth’s spin. More advanced than the basic altazimuth style of mount
Reflector Telescope in which light is gathered by a concave mirror at the bottom of the tube and reflected to a second mirror at the top, where it reflects into an eyepiece
Refractor Traditional style of telescope consisting of a tube with a lens at one end to gather light coming from the stars and an eyepiece at the other to magnify it
STARGAZER’S ALLY
Celestron NexStar 6 SE – typically £699, or £679 from www.telescopeplanet.co.uk
Computer-aided controls and solid optics
Newcomers to astronomy can struggle to recognise heavenly objects but this reflector-style scope has a computerised GoTo mount that aims it at a specific constellation if you enter the name or coordinates. A GoTo mount can be fiddly to set up but this one was easy. The views were good, with the great globular cluster in Hercules a fabulous sight. The Celestron struggled with deep-sky objects and its field of view is narrow, which makes it less suited to observing huge star fields. Keen astronomers can be sniffy about GoTo mounts, but this model is a smart companion for a foray into the night sky.
DEEP SPACE OBSERVER
William Optics FLT 132mm refractor – typically £2,899, or £2,799 from www.iankingimaging.com
Serious money, for serious kit
Astronomy buffs will be agog at this potent refractor-style telescope. Its tube felt solidly hewn, the classy paint finish was resilient to knocks, and it comes in a smart aluminium case. The image quality was superb and even deep-space objects such as nebulae looked crisp with great contrast levels. Colour purity was excellent and the star Vega shone like a diamond. The wide field of view proved well suited to capturing sensational photographs. The price does not include a mount or eyepieces, which push it a tad above £3,000, but this still represents good value, given the quality on offer, and the instrument will give years of pleasure.
SUN WORSHIPPER
Coronado PST – typically £429, or £399 from www.telescopehouse.com
Affordable solar specialist
The sun is the most dynamic object in our solar system, but it’s impossible to view through a conventional telescope without expensive add-on filters. The Coronado PST is designed for solar observation, using filters to block out all light except hydrogen emissions given off by the sun. It was easy to aim and focus and you can tune the wavelength of the filters to keep the most interesting solar phenomena visible. You must factor in the cost of a mount (from £80) and an eyepiece (about £70) and you will need another telescope for the rest of the galaxy. Still, this is a relatively inexpensive way to observe the sun.
PLANET WATCHER
Orion Optics OD150L Deluxe Dobsonian – typically £499, or £399 from www.orionoptics.co.uk
Great views of smaller, close-by objects
This specialist scope is optimised for observing the moon and the planets in our own solar system in detail. It is a reflector model and its mirrors are Hilux-coated to improve contrast and reflectivity. The Orion also has a high focal ratio and a narrow field of view, which helped relatively small objects such as a planet fill the viewing frame. It delivered astonishing lunar sights and – in the right conditions – detailed views of Mars, Jupiter and Saturn. At well over 3ft tall, it is less portable than some models, but it excels at the job of studying our planetary neighbours.
BEGINNER’S BARGAIN
Sky-Watcher Explorer 130PM – typically £199 or £155 from www.acecameras.co.uk
Ideal starter scope for casual stargazers
Proper astronomy need not cost the earth. This reflector-tube design costs less than £200 and comes with a motorised equatorial mount. It offered excellent views of the moon, surface markings on Mars, plus the rings or moons around Saturn – and even a few deep-sky objects. True, the Explorer 130PM was less efficient at gathering light than pricier models. The eyepieces were unimpressive and the mount less than beefy, but this is acceptable at the price and there’s room to upgrade. As a way to dip a toe into the waters of celestial observation, this is excellent.
GUIDING STAR
Meade mySKY – £299 from www.scopesnskies.com
Clever tool flawed by inconsistency
The mySKY is not a conventional telescope but can still help novices explore the night sky. This pistol-shaped gadget bills itself as a personal planetarium with a 2in screen. Point it at the heavens and it uses GPS to identify what you’re looking at and provide images or information on its screen, along with audio via headphones, and even video clips. When the Meade worked it was fantastic, and its GoTo function can help find specific objects. Unfortunately, it was not always correct and sometimes struggled to secure a GPS signal. It’s hard to recommend as anything other than an expensive, albeit sophisticated, toy.
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