Testing Sky-Watcher USA's New Refractor

$Testing Sky-Watcher USA's New Refractor$

EQUIPMENT REVIEW

Sky-Watcher USA’s ProED 120mm Doublet APO Refractor uses a 4.7-inch f/7.5 apochromatic doublet as its objective. The optical tube as- Testing sembly comes with a dovetail mounting plate. Sky-Watcher USA’s ALL IMAGES: ASTRONOMY: JAMES FORBES new refractor A nice package, great performance, and a reasonable price combine The ProED 120mm comes with a 2" star diagonal with a 11/4" adapter, 8x50 finder scope, and to make this 4.7-inch telescope a winner. by Phil Harrington a two-speed Crayford-style focuser.

ince they first hit the U.S. market they have the potential to minimize false mounting rings attached to a 14-inch-long eyepiece while trying to look through the 120mm includes two, a 20mm (that pro- latter’s supernova — fit into the 20mm eye- some 10 years ago, Sky-Watcher USA color caused by chromatic aberration (a (36cm) dovetail mounting plate. other. If this were my own telescope, I duces a magnification of 45x) and a 5mm piece’s field of view. telescopes have become synonymous defect where colors don’t focus at the same The 3-inch-wide (7.6cm) dovetail plate would likely add a separate finder base onto (180x). Nothing on the 20mm eyepiece Image contrast, so important to planet with great value. Whether you’re place) and maximize image contrast. But matches the standard used by both Los- the tube itself. identifies its optical design, although judg- watchers, was also exceptional. Fine details Stalking about refractors or reflectors, these how do they perform in actual use? mandy and Celestron. It’s the second most I’d make no change to the Crayford- ing by the apparent field of view, I suspect it in Jupiter’s many belts, for instance, showed high-quality instruments promise real bang common size in use today, usually reserved style focuser, which offers both coarse and is a Plössl. The 5mm carries the label “Sky- clearly. An oft-cited observing rule says not for your observing buck. The package arrives for carrying heavy telescopes. For this test, fine focusing. The left knob is for coarse Watcher 1.25" – 5mm UWA 58°.” The com- to exceed a magnification of 60x per inch of Sky-Watcher USA offers three instru- To answer that question, I recently tested the however, I substituted my own Vixen-style adjustment only, while the right also pany calls them the LE20mm and the aperture. Yet on rare nights of steady seeing ments in their line of ProED Doublet APO flagship version — the ProED 120mm Dou- bar, which is 1.75 inches (4.4cm) wide and includes a built-in 10:1 speed reducer for LE5mm, where “LE” stands for “long eye and given a high-quality eyepiece, the Refractors, with apertures of 3.2, 3.9, and blet APO Refractor. The telescope arrived the most common version. The ProED fine-tuning. You can lock the focuser in relief.” Both performed well, and I also ProED 120mm easily handled 50 percent 4.7 inches (80, 100, and 120 millimeters). well packaged in double cardboard boxes 120mm optical tube assembly weighs 11.3 position with the twist of a thumbscrew viewed through many of my own eyepieces. more magnification than the stated “limit.” “APO” stands for “apochromatic,” which and secured inside a custom-fit aluminum pounds (5.1 kilograms) and measures 37.79 threaded into the underside of the housing. Overall, Sky-Watcher USA’s ProED means the main optic has a high degree of carrying case measuring 40 by 9 by 12 inches inches (96cm) long. My medium-duty Ger- Looking at the other accessories, both Star light, star bright 120mm Doublet APO Refractor is a solid color correction built in. (102 by 23 by 30 centimeters). Together, they man equatorial mount carried it easily. the 2" star diagonal and 1¼" adapter use I put the scope to the test against some of performer. Apart from my minor comment At the heart of all three scopes are two- protected their delicate contents from any internal compression-style clamps to hold the targets in the midwinter sky. My first about finder placement, this scope deserves element objective lenses of extra-low dis- chance of damage during shipping. Fit and finish eyepieces securely while not marring their stop was the Moon. When viewed through high marks for optics, mechanics, and a persion (ED) glass. Each front element is When I opened the aluminum case, I The aluminum telescope tube sports a barrels’ finish. This feature is a nice touch, most achromatic refractors, the lunar limb great price point. Schott BK-7, while the rear element is FPL- saw the telescope nestled in a foam cradle, beautiful finish of high-gloss black paint and it speaks to the care the manufacturer (edge) likely contains tinges of blue, purple, 53, two of the most advanced types of glass along with the standard accessories Sky- speckled with gold flakes. It gives the took. Both the diagonal and the adapter or yellow. An apochromatic refractor like available. And Sky-Watcher USA gives both Watcher USA supplies with the instrument. impression of stars floating in a crystal- also have internal threads to accept filters. the ProED 120mm should eliminate this PRODUCT INFORMATION state-of-the-art multicoatings. Together, These include an 8x50 right-angle, erect- clear sky. Both the (nonsliding) dew shield While many upper-end telescopes these false color entirely. And in practice, it did. image finder scope with mount; a 2" dielec- and focuser are eggshell white, as are the days do not include eyepieces, the ProED Shadows covering crater floors were Sky-Watcher USA ProED 120mm Phil Harrington is a contributing editor of tric star diagonal with a 1¼" adapter; 5mm mounting rings and finder bracket. appropriately pitch black rather than a Doublet APO Refractor Astronomy and a longtime equipment guru. and 20mm 1¼" eyepieces; and a pair of tube Inside, the tube is well baffled and milky gray. Craters and mountain ranges Optical design: Apochromatic refractor painted a uniform flat black to minimize were all crisp and sharp. Very nice! Lens: Two elements, extra-low dispersion any stray light entering the optical path and My next stop, Sirius, is a notoriously Aperture: 4.7 inches (120 millimeters) washing out the view. unforgiving object for chromatic aberra- Focal length: 900 millimeters Sky-Watcher USA configured the 8x50 tion. I saw only minor evidence of false Focal ratio: f/7.5 right-angle finder scope to deliver an erect color through the supplied eyepieces. Weight: 11.3 pounds (5.1 kilograms) image, which makes star-hopping much I put the scope’s relatively short Includes: Two-speed 2" Crayford-style easier. The finder’s mount uses a spring- focal length (900mm) to good use focuser, 8x50 finder scope, 2" star diag- loaded piston combined with two thumb- as I enjoyed wonderful views of the onal with 1¼" adapter, 20mm (45x) and screws for a quick and easy alignment. Orion Nebula (M42), the Pleiades 5mm (180x) eyepieces, tube rings with My only complaint about the telescope (M45), and the Double Cluster in dovetail mounting plate, foam-lined concerns where the finder mount sits. Its Perseus (NGC 869 and NGC 884). aluminum carrying case slide-in base is cast into the focuser hous- Ursa Major’s dynamic galactic duo, Price: $1,549 ing, which puts the finder’s eyepiece close Bode’s Galaxy (M81) and the Cigar Contact: Sky-Watcher USA to the one on the telescope. With some eye- Galaxy (M82) — complete with the 475 Alaska Avenue pieces I tried, I found that my head hit one Torrance, California 90503 [t] 855.327.1587 The telescope’s light-collector is a 4.7-inch f/7.5 Sky-Watcher USA packs the ProED 120mm into apochromatic doublet lens with each element [w] www.skywatcherusa.com a foam-lined aluminum carrying case. made of extra-low dispersion glass.