| The TeleVue TV-102 is a 102mm (4-inch) f/8.6 refractor that coaxes apochromatic performance out of an ED glass doublet objective lens. The scope body is ivory, with black trim, and is very solidly built. It has a retractable self-storing dewshield and a 2” rack-and-pinion focuser with helical-cut gears. The focuser has a silky-smooth motion and oversize knobs that make it easy to achieve sharp focus, even at very high powers. The TV-102 comes with a 2” Everbrite dielectric coated star diagonal with 99% reflectivity and a 1.25” accessory adapter. Focuser, diagonal, and 1.25” adapter are all equipped with non-marring brass clamp ring accessory holders. The supplied hardshell carrying case has cutouts to cradle the scope, diagonal, and a number of eyepieces. According to a Sky & Telescope review, “star images were almost textbook perfect. At 220x diffraction patterns were identical inside and outside of focus, with the outer fringes having a yellow-green tint outside and purple-magenta inside. The important test of color, however, is when the telescope is sharply focused. As such, only the most brilliant stars, such as Vega, show hints of a blue halo and momentary sparkles of color as the diffraction rings ripple in the seeing. Atmospheric turbulence is a factor in showing this false color, since I did not notice the halo under calm conditions. Furthermore, at magnifications of 175x and lower or when viewing fainter stars I discerned essentially no false color around any star, and the limb of the full Moon remained razor sharp and color free. ”One particularly memorable testament to the scope's color correction came with an observation of the well-known Double-Double, Epsilon Lyrae. Using a 3-mm Tele Vue Radian eyepiece yielding 293x, both pairs of stars were cleanly split in one field of view. They appeared like miniature versions of the colorful double Albireo, with the bright components appearing yellowish and contrasting nicely with the fainter bluish companions. ”The interior of the optical tube is covered with a flat-black textured material that is so effective at suppressing reflected light that there is no need for internal baffles. Even as I moved the full Moon around the field of view, the background sky remained a contrasty inky black with surprisingly faint stars visible near the lunar limb. ”The contrasty views were also great for the planets. It was easy to become so absorbed with the views of Jupiter and Saturn that minutes turned into hours. Shadow transits on Jupiter appeared as sharp black dots. On the evening of October 26th I had one of the finest views of a Galilean moon transit I've ever had with a scope this size. Europa's subtly brighter disk was easily seen against the planet's cloudtops. Even in average seeing, all four Galilean moons appeared as distinct disks; this was especially apparent when there were stars in the same field with which to compare them. Saturn always showed cloud bands on the planet's ball, and there were numerous times when I caught glimpses of ring detail usually reserved for views in much larger scopes.” From very low power to very high, there’s no drop-off in the TV-102’s performance. An optional 2” TeleVue 55mm Plössl has a magnification of 16x, a 3 degree field of view, and a 6.4mm exit pupil for wide-field scanning of large faint deep space objects such as Andromeda and the Veil Nebula. At the other end of the spectrum, an optional TeleVue 3mm Radian eyepiece gives a power of 293x and a field about 12.5 arc minutes across. While this magnification is well above the often-recommended upper limit of 50x-60x per inch of aperture, the Sky & Telescope review commented, “I frequently found myself using it for the Moon, planets, and double stars. Indeed, there were numerous occasions when I had satisfying views at 100x per inch of aperture. I'm not about to start a flap on the Internet news groups by admitting in print how far I pushed the magnification with this scope, but I will say that I had 5-, 4-, and 3-mm Radian eyepieces and a 5x Powermate amplifying lens available while testing the telescope.” The scope comes with a 4-inch tube ring that clamps around the tube and is drilled and tapped with a 1/4”-20 thread mounting hole. This allows the scope to be mounted on a camera tripod, but a better choice would be the very stable TeleVue Gibraltar altazimuth mount. Most observers wouldn’t normally consider an altazimuth mount with no slow motion controls for high power use. However, even the 3mm Radian has such a large field with the TV-102 that planets stay in view for more than 45 seconds when the telescope is stationary, so the nondriven Gibraltar mount shouldn't be ruled out. For spur-of-the-moment astronomy, with virtually no setup time, the TV-102 and Gibraltar mount form an attractive combination. For those who prefer an equatorial mount with motor drive capabilities, however, the Losmandy GM-8 or the Celestron CG-5 would be good choices. As the reviewer concluded in Sky & Telescope, “During my weeks of testing the Tele Vue-102 I was constantly impressed with how nice the view was through the eyepiece . . . conventional wisdom holds that you can't see detail smaller than the Airy disk. But that's not so. On the evening of November 8th the waxing gibbous Moon passed just north of 4.6-magnitude 33 Piscium. I could view the star and the Moon's southern highlands simultaneously with enough magnification to easily show the star's Airy disk. I could clearly see linear shadow detail on the Moon that was smaller than the Airy disk . . . Reviewing the Tele Vue-102 also made me rethink my position on using such a small aperture for deep-sky observing. Certainly this isn't the instrument if your primary mission is to hunt down 13th-magnitude galaxies in the Virgo Cluster. But, on the other hand, you can't dismiss this scope for serious deep-sky work. It does a very acceptable job on the popular deep-sky objects that most amateurs turn to first, such as those in the Messier and Caldwell catalogs . . . No matter how you look at it, the Tele Vue-102 is an impressive telescope that's sure to be appreciated by anyone who uses it.”
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