Sponsored by A supplement to Astronomy magazine Special advertising section HOW TO BUY YOUR FIRST TELESCOPE INSIDE THIS HANDBOOK, you’ll find the main telescope types, answers to common questions, descriptions of eyepieces and accessories, and what you should look at first. By the editors of Astronomy magazine : Jay Smith; background: Tony Hallas; product shots: Celestron 618261 © 2011 Kalmbach Publishing Co. This material may not be reproduced in any form without permission from the publisher. www.Astronomy.com Telescopes 101 Buying your first telescope is a big step, especially if you’re not sure what all those terms mean. So, to help you understand what to look for in a quality telescope, the editors of Astronomy To see objects through magazine answer 11 of the most-asked questions. your scope in their normal orientation, you’ll need an accessory called an image I know telescopes make I’m interested in observing. erector. Celestron 1 things appear bigger, but 3What should I do first? what exactly do they do? Learn all you can about telescopes: what Why are objects through my A telescope’s purpose is to collect light. types are available, the best accessories, and 5telescope upside-down? This property lets you observe objects what you’ll see through them. This publica- Because of the way a telescope focuses light, much fainter than you can see with your tion is a good start because you’ll see a wide the top of what you’re looking at is at the eyes alone. Italian astronomer Galileo Gali- range of options. bottom as it enters the eyepiece, and vice- lei said it best when he declared that his If a telescope interests you, visit www. versa. You can re-flip the image with an telescopes “revealed the invisible.” Celestron.com to read more about it. You’ll accessory called an “image erector,” but also find telescope reviews online at www. you’ll lose a bit of the object’s light. And for Will my telescope be complete, Astronomy.com/equipment. You’ll learn faint sky objects, you want the maximum 2or will I need additional items what’s important to veteran observers when amount of light possible to reach your eye. to make it work? they use a telescope. You’ll also get a feel for Besides, there’s no up or down in space, and Most Celestron telescopes are complete mechanical quality, ease of use (including with most objects, you won’t even know systems, ready for the sky as soon as you portability), and extra features. they’re upside-down. unpack and assemble them. A few models are “optical-tube assembly only.” This Should I buy binoculars Can I use my telescope for means all you’re buying is the optics in the 4before I buy a telescope? 6views of earthly objects? tube with no tripod or accessories. No. The view through binoculars — espe- Absolutely! Many nighttime observers cially near a city — won’t be what you (usually those with smaller telescopes) also expect. They are, however, a valuable acces- use their telescopes for bird-watching or sory at a dark site. Star clusters look great other daytime nature-watching activities. through them, as do the Milky Way, meteor Here’s where the image erector (see #5) trails, and the Moon. Learn more about comes in most handy. binoculars on page 11. Celestron’s AstroMaster 70AZ is a complete system. It comes with the telescope, a tripod, two eyepieces, and more. Celestron 6" Your telescope also can give you great nature views, like the one of this painted bunting, in 3" the daytime. Howard B. Cheek Objective Eyepiece Any mirror (or lens) twice as large as another captures four times as much light. Light rays To eye So, a 6-inch mirror Aperture collects four times the light as one 3 inches across. fo fe Astronomy: Roen Kelly Objective Eyepiece focal length focal length Telescopes flip the view of your target, which doesn’t matter at all if you’re looking at an object in space. Astronomy: Roen Kelly HOW TO BUY YOUR FIRST TELESCOPE 2 high winds, but a poor mount will transfer vibrations even in a light breeze. So, be sure Celestron’s your scope sits on a high-quality mount. NexStar SLT Computerized Is a “go-to” scope better Mount is 9 than one without go-to? compatible with Yes. A go-to telescope is one with a motor many of the company’s or motors controlled by a built-in com- telescopes. puter. Once set up for an evening’s observ- Celestron ing, a go-to scope will save you lots of time by moving to any sky object you select and then tracking it. Even experienced observ- A local astronomy club’s observing session, or ers prefer go-to scopes because they leave a star party like the one pictured here, is a great more time to observe the sky. place to “test-drive” a telescope. Celestron If I use my telescope outside, Is there a way for me to 10 does it need electricity? 7 “test-drive” a telescope? Only if it has a motorized drive. In most Yes. Look in your area for an astronomy cases, telescope drives use direct current, club and visit one of its meetings, which which means you can use batteries (includ- usually occur monthly. There, you’ll find ing the one in your car). others who enjoy the hobby and are willing Adapters available from to share information and views through the manufacturer will their telescopes. At one of the club’s stargaz- let you plug your ing sessions, you’ll be able to look through scope into an electri- many different telescopes in a short period cal outlet. and ask all the questions you like. What’s Apart from quality optics, 11 the best 8 what’s the most important telescope for me? thing in a telescope system? It’s the one you’ll use the most. If it takes The mount, which is what the telescope’s an hour to set up a scope, or if your scope tube sits on. You can buy the finest optics is large, heavy, and difficult to move, you on the planet, but if you put them on a low- might observe only a handful of times quality mount, you won’t be happy with each year. If, on the other hand, your scope your system. No telescope can function in is quick to set up, you may use it several times each week. A small telescope that’s used a lot beats a big scope collecting dust Celestron’s FirstScope is an ideal “grab and go” in a closet every time. telescope: It’s small, light, and sets up on any level surface. Celestron A go-to mount, like the one included with Celestron’s NexStar 4SE telescope, makes observing easier. The mount’s computer contains a database of nearly 40,000 celestial objects. Celestron This adapter will let you power your scope from a car’s cigarette lighter. Celestron 3 Sponsored by Celestron All about refractors THINGS YOU 3 SHOULD KNOW here light is concerned, the word First, the overall quality of refractors has • Refractors use a lens system to refract means “to bend.” A refract- risen dramatically. Second, better lenses produce images. Wing telescope (usually called a have made shorter tubes possible. Finally, • Refractors require the least refractor) does this with a carefully made lighter materials mean small models now maintenance of all telescopes. lens system. If the surfaces of the lenses transport more easily. Not only does this • Many small refractors are light have the proper shape, the light will come simplify travel to your favorite viewing site, enough to mount on a sturdy to a focus. Placing an eyepiece at that “focal but it also helps you decide whether or not camera tripod, making them the point” will let you see what you have to set your scope up in the backyard for a ultimate grab-and-go scopes. pointed the telescope at. quick view of the Moon or Jupiter. Dutch eyeglass-maker Hans Lipperhey made the first telescope (a refractor) in 1608. His patent application described “an Lens shade instrument for seeing faraway things as Eyepiece though nearby.” The tube magnified objects Light about three times. Italian inventor Galileo Telescope tube enters Lens here Galilei was the first to use the telescope to study celestial objects, and what he saw revolutionized astronomy forever. Focuser Two words you’ll see when reading about today’s refractors are achromat and A refractor uses a lens (a combination of two to apochromat. Each is a lens system combin- four polished glass pieces) to bring light to a ing different types of glass. Achromat focus. Astronomy: Roen Kelly, after Celestron means “not color dependent.” Such a lens has two pieces of glass and does a pretty good job of bringing all colors of light to the same focus. Apochromatic lenses are also available. They are the top of the Celestron’s PowerSeeker line, and their front lenses com- 60AZ is an example of a bine up to four pieces of glass. small, low-priced refractor. Into the 1960s, refractors topped It has a 2.4-inch lens, sits all telescopes in terms of numbers sold. on a simple mount, and produces right-side-up Then, as manufacturers began making large images with the supplied scopes of other designs, sales of traditional diagonal. Celestron refractors fell. In recent years, however, refractor sales have made a dramatic come- back due to several factors you may want to consider when you buy a telescope.