Astronomy March2016 Delite Review.Pdf

EQUIPMENT REVIEW to help prevent an errant eyepiece from blue, and twin-lobed, somewhat reminis- falling to the ground. cent of the Little Dumbbell Nebula (M76), When I test eyepieces, it’s important to although the emphasis was on the lobes Select these eyepieces to enhance your observing me to use them in a variety of telescopes so rather than the center. without ruining your credit. by Tom Trusock I can understand what aberrations the tele- Finally, I took the time to check the scope adds to the design. Through the contrast with the Fetus Nebula (NGC We test years, I’ve seen amateurs blame specific 7008). With a bright star just off the edge of aberrations on eyepiece design that were this planetary nebula, its large size and low the fault of the telescope. Always remem- surface brightness can make it difficult to ber, we deal with an optical system. pick out the distinctive shape, but it was in Because of this, I’m careful to review eye- clear view through the DeLites. pieces in various telescopes I am already familiar with. For this review, I used an Comparing sizes Tele Vue’s DeLite 18-inch f/4.5 Newtonian reflector These are excellent eyepieces. But which (equipped with the Tele Vue Paracorr), a one did I prefer? I found that my favorite 3.6-inch f/7 apochromatic refractor, and a eyepiece depended greatly on the telescope 6-inch f/15 Maksutov reflector. I used it in. Overall, each DeLite performed My testing showed all three scopes per- similarly, so I matched magnification to formed similarly, so the comments in gen- sky conditions. I typically wound up using eral apply to all. My initial views came Paul Delechiaie designed the DeLite eyepiece between 100x and 200x for a given tele- line for Tele Vue Optics. His previous credits eyepieces during the daytime, and they impressed scope. In the two short focal length scopes, include the company’s popular Ethos and Delos me. When I scanned a field of view with eyepiece lines. COURTESY TELE VUE OPTICS I preferred the shortest focal length eye- objects at the same distance, the entire field piece and vice versa. yepieces are a visual astronomer’s was in focus, implying little, if any, field Tele Vue lists the field stops for each window to the universe. And his- curvature. Using conveniently placed local interchange eyepieces without touching eyepiece as 19.1mm (for the 18.2mm tory shows that Tele Vue led the landmarks, I found both rectilinear and focus. The DeLites are a good choice for DeLite), 11.7mm (for the 11mm), and revolution in high-quality wide- angular distortion to be well controlled, use in daytime spotting scopes. 7.5mm (for the 7mm). This is important if field eyepieces with its introduc- meaning parallel lines remained parallel you want to find the true field of view (in Etion of the Nagler line in the early 1980s. and objects kept their proportions Under the sky degrees). For any eyepiece/telescope combi- Company founder Al Nagler was the driv- throughout the field. At night, contrast was superb, enabling me nation, divide the field stop diameter by ing force and principal optical designer on Because of the 20 millimeters of eye to make out fine detail within the plan- the focal length of the telescope (in milli- all eyepieces until the introduction of the relief, the eyepieces were comfortable to etary bands of Saturn. And in the rings, the meters) and multiply the result by 57.3. So, Ethos line, when protégé Paul Delechiaie view through, and with proper use of the Cassini Division was obvious through the an 8-inch f/10 Schmidt-Cassegrain tele- stepped up to the plate. Delechiaie went on eye guard, I experienced no blackout. two smaller scopes. The eyepieces showed scope that has a focal length of 2000mm to design the Delos line and, most recently, Through the years, I’ve found some eye- no sign of scattered light or ghost images, will yield true fields of view around 0.55°, the DeLite line. pieces to be warm (yellow bias) and others and transmission was quite good. Also, 0.34°, and 0.21° for the 18.2mm, 11mm, Tele Vue targeted the DeLites, intro- cool (blue bias). Here, each DeLite eyepiece I noted no glare or internal reflections. and 7mm eyepieces, respectively. duced just before the 2015 Northeast particularly impressed me by its decidedly Although I tend to prefer using single eye- Astronomy Forum convention, at observers neutral color tone. pieces to achieve desired magnifications, Bottom line looking for an economical high-end eye- As I get older, I’m losing some of my that’s not always possible. So, it was good With the departure of the Tele Vue Radian piece that’s small and light yet provides visual accommodation. This difficult to learn that these eyepieces worked well line — a lightweight eyepiece with tons of diffraction-limited performance, high con- admission ironically makes it easier to with Barlow lenses. eye relief — many observers were hoping trast, and generous eye relief. check if eyepieces are parfocal (whether I then moved to other targets. Through for something to fill that void. With excel- each holds focus without touching the the 6-inch, the gold and blue of Albireo lent contrast, great eye relief, and a decent Details scope’s focuser). After establishing critical (Beta [β] Cygni) simply popped. Through apparent field of view, the DeLites do just These 1¼" eyepieces are initially available focus with the 7mm, I found that I could the 18-inch, the Hercules Cluster (M13) that. The only caveat is that they are cur- in three focal lengths: 7mm, 11mm, and was a jellyfish of suns against a deep-black rently available in only three focal lengths. 18.2mm. Priced at $250 each, they feature background, and stars were pinpoint out to While the range is well chosen for an a 62° apparent field of view, 20mm of eye PRODUCT INFORMATION the edge of the field. initial offering, users of shorter focal length relief, an adjustable locking eye guard, and Staying with the big eye, the Ring scopes will need to use a Barlow lens if they compatibility with Tele Vue’s astigmatism Tele Vue DeLite eyepiece line Nebula (M57) was a frosted doughnut, want to obtain high magnification. correction system, the Dioptrix. Focal lengths: 7mm, 11mm, and 18.2mm nicely showing striations in the center with However, I’d be surprised if the company The DeLites are well suited for use in Eye relief: 20mm barred spiral galaxy IC 1296 a fairly easy doesn’t address this down the road. large binoculars or binoviewers due to their Apparent field of view: 62° catch off to the side. The Blinking Tele Vue has once again created a line of reasonable weights, 7.3, 7.1, and 7.6 ounces Price: $250 each Planetary (NGC 6826) was also a treat. all-around excellent eyepieces, good for Tele Vue’s DeLite eyepiece (207, 201, and 215 grams, respectively). All Contact: Tele Vue Optics Distinctly bluish-green in color, both the both planetary and deep-sky work. Selling series offers significant sav- feature the Tele Vue barrel safety undercut 32 Elkay Drive inner and outer shells were well defined. points are long eye relief, a small and light ings over other high-quality Chester, NY 10918 If you’ve never seen planetary nebula design, and the relatively inexpensive cost. eyepiece lines. The com- Tom Trusock loves testing new equipment, [t] 845.469.4551 pany launched the DeLites NGC 7027 in a large scope, I highly recom- The DeLite line should be on your must- with three focal lengths. attending star parties, and observing for the fun [w] www.televue.com mend it. Viewing through the 18.2mm view-through list of eyepieces at the next COURTESY TELE VUE OPTICS of it from his home in Ubly, Michigan. DeLite eyepiece, the object appeared small, star party. 64 ASTRONOMY • MARCH 2016 WWW.ASTRONOMY.COMWWW.ASTRONOMY.COM 6565.

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