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TELESCOPE REVIEW Designed for portability and ease of use, this reflector features more than 3 inches of aperture. / / / BY PHIL HARRINGTON Backpack this scope These days, telescopes come in a variety of shapes and sizes. No matter which astronomical niche you’re interested in, there seems to be a telescope to fit your needs. That is, except for one. What about a telescope for the youngest astronomers? Even the smallest refractors and reflectors are usually too large and too heavy for small-fry stargazers to handle, which means they either have to rely on an adult to set up the telescope for them or do without. To help fill this gap, Celestron recently introduced the 3.1-inch f/6.9 ExploraScope, a miniature Newtonian reflector poised on a unique tabletop base. The ExploraScope weighs only 5 pounds and measures 14" long, making it small and light enough for a 7-year-old to carry. The ExploraScope’s gourd-like shape is reminiscent of Edmund Scientific’s venerable Astroscan, which can trace its own roots to amateur telescopes made more than 30 years ago. Overview The ExploraScope’s optics are enclosed in a white, molded-plastic tube assembly. Two wing-like bulges serve as grips for either holding or guiding the telescope. A carrying strap is attached between the wings. Realizing a conventional altitude-azimuth or equatorial mount would be too cumbersome for kids, Celestron placed the ExploraScope on a small, concave base. This design lets users aim the telescope in any direction simply by pointing. No axes need to be negotiated, and no screws lock or unlock. Just point the telescope, and let it go. Users who prefer a more conventional mount will find an adapter included for attaching the instrument to a photo tripod. Be sure to check the adapter connection, as I found it would work its way loose unless it was tightened down firmly. The ExploraScope comes with a 12.5mm eyepiece already mounted in the telescope’s cleverly designed helical focuser. The eyepiece threads into a collar that travels up and down a track inside the drawtube as an observer turns the black-plastic focusing ring. The eyepiece magnifies 44x. The ExploraScope provides a right-side-up view by employing a built-in lens at the focuser’s base. Focusing is smooth, without binding or dead spots. The ExploraScope is designed to let adult users collimate both the primary and secondary mirrors. To adjust the primary, pop off three plastic plugs located at the bottom of the tube assembly. Inside are three Phillips screws that adjust the main mirror. THE EXPLORASCOPE’S FOCUSER is a knurled, black ring located below the eyepiece. The front protective cover slides into place easily and keeps dirt out. ASTRONOMY: WILLIAM ZUBACK Another trio of Phillips screws allows adjustment of the secondary mirror, which is held in the tube by a three-vane spider mount. The ExploraScope’s instruction pamphlet includes some rudimentary instructions on aligning the telescope’s optics, but if you’re unfamiliar with collimation, seek a helping hand from an experienced amateur astronomer. Setup’s a snap The ExploraScope is ready to use right out of the box — no assembly is required. Just place the telescope in its base on a picnic table or other sturdy surface, and it’s set. For the test, I restricted my explorations to objects kids would be interested in viewing, such as the Moon and bright planets. Initially, I found images were not as crisp as in some other small, inexpensive telescopes I’ve used. Removing the screw-in eyepiece and looking into the focuser revealed both mirrors were slightly out of collimation. Once they were aligned properly, image sharpness improved somewhat but still left something to be desired. Part of the problem lies with the ExploraScope’s inexpensive eyepiece, and the inverter lens in the base of the focuser may be responsible for the remaining lack of sharpness. That leads to one of my disappointments with the ExploraScope. Although I like the focuser’s design, it’s just a little too small. The ExploraScope’s eyepiece looks like it has a standard 1¼" barrel that’s threaded for filters. But it’s not. It turns out the eyepiece barrel measures only about 1.2 inches, which means the focuser’s drawtube is 0.05" too small to accept 1¼" eyepieces. That’s really a shame because images could be improved by substituting even an inexpensive Plössl eyepiece. A 6mm Kellner eyepiece, which yields a magnification of 92x and which is sized for the ExploraScope, is available from Celestron dealers for $20. © 2009 Kalmbach Publishing Co. This material may not be reproduced in any form without permission from the publisher. www.Astronomy.com CELESTRON’S EXPLORASCOPE is a great first telescope for young astronomers. ASTRONOMY: WILLIAM ZUBACK www.astronomy.com 93 Life with the ExploraScope improved after I attached a small, red-dot, singlepower finder to the tube, and I’d recommend anyone buying the telescope do the same. Keep in mind, however, that because the tube is tapered, you’ll need to shim the finder (I used a washer) in order to make it parallel to the telescope’s optical axis. You try it THE EXPLORASCOPE’S TABLETOP BASE is included and provides a stable platform for observing. ASTRONOMY: WILLIAM ZUBACK Under the sky When I pointed the ExploraScope at the Moon, I saw a wealth of surface features, including the central peaks of the craters Tycho and Copernicus. The Straight Wall was plainly visible, as were countless small craters. Of the planets, Venus’ phase was evident, as were Jupiter’s four Galilean moons and Saturn’s rings. I could make out a hint of Jupiter’s two equatorial belts, but I couldn’t see the Cassini Division in Saturn’s rings. I also visited several bright deep-sky objects. While observing them, I measured the eyepiece’s true field of view at approximately 0.9°, close to Celestron’s stated value of 1°. The Pleiades (M45) cluster put on a nice show. The Orion Nebula (M42) showed its characteristic shape along with the four stars of the Trapezium buried inside. Several bright globular clusters — M13, M15, and M92 — were apparent, although the small aperture couldn’t resolve individual stars. Finally, some well-known double stars, such as Albireo (Beta [β] Cygni), were split easily. Observing quickly revealed the biggest shortcoming of a scope like this: It’s difficult to aim. The lack of a finder scope meant I had to scan back and forth until the target crossed the field of view. The Moon’s glare made it easy to acquire, but even Venus, blazing brilliantly in the morning sky, took some effort to locate. A LOOK INTO THE EXPLORASCOPE reveals a secondary mirror that can be collimated by adjusting three screws. ASTRONOMY: WILLIAM ZUBACK Phil Harrington is the author of the new observing guidebook Star Watch, which is published by John Wiley & Sons. 94 astronomy /// february 05 Of course, Celestron was not trying to appeal to me when it introduced the ExploraScope — the company designed the telescope for kids. With that in mind, I loaned the ExploraScope to my brother Steve and his family. He and his wife, Ann, have two kids: Lilia, who is 8, and Dan, 4. None has any working knowledge of telescopes (I just didn’t rub off on Steve during childhood), which probably makes them typical of those who will purchase ExploraScopes. What did they think of it? After using it during both the day and night, they came away with a few interesting points. Lilia especially liked being able to carry the telescope herself using the shoulder strap, and she thought setup was a snap. But the simple design of the telescope’s base also worked against it during use. Because there is no way to lock it in place, they found that it was easy to throw the telescope off its target when changing observers. Like many adults who are unfamiliar with viewing through an eyepiece, the kids grabbed the scope when viewing. And unless focusing was done gently, it threw off the telescope’s aim. Like me, the family members /// PRODUCT SPECIFICATIONS CELESTRON EXPLORASCOPE • 3.1-inch (80mm) Newtonian reflector • 550mm focal length at f/6.9 • 12.5mm eyepiece included • Carrying strap included • True field of view: 1° Length/weight: 14 inches/5 pounds Street price: $60 to $70 CONTACT INFORMATION: Celestron International 2835 Columbia St. Torrance, CA 90503 [t] 310.328.9560 [w] www.celestron.com had one problem: aiming the telescope. In the end, they entertained themselves by scanning the sky back and forth rather than selecting targets, save the Moon. Although there is no suggested minimum age on the box, I’d surmise the range is 7 to 10. A few parting remarks Most results from testing the ExploraScope were positive. On one hand, Celestron produced a lightweight telescope kids can carry and set up on their own. Images are reasonably sharp and easy to focus. On the other hand, the telescope lacks a finder scope and is easily knocked off target because it’s held in place by gravity alone. While the ExploraScope has some drawbacks, it is still better suited for young astronomers than any department-store telescope. As my friend Geoff Gaherty put it, “many small telescopes are really toys in disguise, but Celestron’s ExploraScope is actually a telescope disguised to look like a toy.” So, parents, if a small, portable telescope is on your child’s gift list, the ExploraScope just might be right for him or her. 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