贴一篇ASTRONOMY今年9月份对TV76的评测

呵呵，这可是最新一期啊。
仅供参考，考虑到版权问题，请版主1周后删除

HAVE SCOPE WILL TRAVEL  

The Tele Vue 76 offers quality views with easy transport.

The Tele Vue 76 is A1 Nagler's newest entry in a long line of high-quality refractor telescopes. It offers quality views and ease of transport for those who must travel to their favorite dark-sky observing site. Just remember to pack your favorite equatorial mount, as the unit is sold separately from any accessories. But if excellence in a small package is your goal, the Tele Vue 76 may be the scope for you.


A Hands-On Survey
I recently put a Tele Vue 76 (TV 76) scope through its paces under Arizona's autumn and winter skies. Early on I decided that operating this instrument on a photographic tripod was cruel and unusual punishment for both the telescope and its operator. Thereafter, I piggybacked the TV 76 on my equatorially mounted 14-inch SCT as it tracked the westward motion of the sky above the high desert.

The TV 76 is compact. Its 21-inch (53-cm) long foamlined soft carrying case, which has cutouts for six eyepieces or adapters, will fit easily in an airliner's overhead compartment. Overall, the telescope weighs in at less than seven pounds (3 kg). Its maximum length, with lens hood extended and 2-inch diagonal at extreme back focus, is only 22 inches (56 cm). This compresses to 17 inches (43 cm) for packing in the case. Traveling observers must remember to bring a mounting.


Rich-Field Optics: A Wide-Angle View
The TV 76, as its name implies, has an objective lens 76mm (3 inches) in diameter and a focal length of 480mm, yielding a focal ratio of 6.3. This relatively short focal ratio qualifies it as a "rich-field" telescope. A rich-field scope produces spectacular low-power views of wide areas of the Milky Way and of objects such as the Pleiades star duster and the Andromeda Galaxy, all of which are too large in angular diameter to fit into the field of most larger telescopes. The TV 76's maximum theoretical field of view (with a long-focus eyepiece) is 5. For comparison, Orion's belt is only 3 across and the "pointer" stars in the bowl of the Big Dipper are 5* apart.

By timing the transit of a star on the celestial equator across the field of view, I determined empirically the telescope's true field of view in two different eyepieces. The Nagler 31mm Type 5 (lovingly known to its users as "the pineapple," or sometimes "the hand grenade") yields a field of view of 5 and a magnification of 15x. The 20mm Tele Vue P1ossl eyepiece -- supplied with the TV 76 kit -- provides a 2 field of view and a magnification of 24x. The four settings of the new 3mm-6mm Nagler Zoom eyepiece increased the view to the following magnifications: 6mm -- 80x; 5mm -- 96x; 4mm -120x; 3mm -- 160x.


Optical Test Grade: A
I tested the optical quality of the TV 76: Starting with inside-and-outside-of-focus star tests and split double stars, I then looked at bright stars and the moon for signs of internal glare and chromatic aberration. After that I performed a side-by-side comparison of the TV 76 against a friend's 76mmaperture, 600mm-focal length Takahashi refractor.

The 3-inch objective lens of the TV 76 is a multicoated two-element design whose exotic glasses give the optical performance of an apochromatic objective lens. Traditional two-element achromatic designs leave an annoying color fringe around bright objects because achromats often have difficulty bringing the different colors of light fully to a common focus. The TV 76 passes the bright-object test with (pardon the expression) flying colors. A look at the bright stars Vega and Capella, with magnifications ranging from 24x to 160x, revealed only a faint violet haze around the star.

I found an almost imperceptible glitch in the TV 76's field of view when using a low-power eyepiece such as the Nagler 3 lmm: The field appeared somewhat curved, leaving stars at the edge at a slightly different focus than stars in the center of the field. Only those wishing to do astrophotography will even notice this and should use Tele Vue's field-flattening lens.


The Moon
The moon seen through the TV 76 is tack-sharp at all magnifications, with no glare or false colors in the view. Stars near the bright limb of the moon are easily picked out because of the absence of glare in the telescope.


Double Stars and Planets
In-and-out-of-focus star tests, star diffraction patterns, and the ability to resolve various double stars reveal the TV 76's top-notch optical quality. If the atmospheric seeing permits, the TV 76 easily resolves doubles with a separation at the theoretical limit for a 76mm aperture scope of 1.6". Planetary views in the TV 76 are best seen through the higher magnifications offered by the 3mm-6mm Nagler Zoom eyepiece. Jupiter and Saturn reveal subtle color variations and both planets' retinues of moons are visible. When the seeing conditions are good, the TV 76 reveals atmospheric belts on Jupiter beyond the two prominent equatorial belts, as well as Cassini's division in the rings of Saturn.


In Its Element: The Deep-Sky
When used as a rich-field scope for deep-sky viewing, the TV 76 excels. With a long focus eyepiece in the 2-inch diagonal, the scope offers impressive views of "showpiece" objects that are too large in angular diameter to fit into the smaller fields of view of larger telescopes. Under a dark Arizona sky, the Andromeda Galaxy (M31) shows its full 3 extent, including its central dust lanes and two companion galaxies -- M32 and NGC 205. Dozens of stars in the Pleiades cluster look like sparkling diamonds scattered on black velvet.

The TV 76 "light cup" provides surprisingly good views of large nebular objects. I threaded Lumicon's UHC (Ultra High Contrast) filter into the "pineapple" eyepiece (i.e. the Nagler 3 lmm Type 5) and it yielded clear views of the full extents of the North America Nebula and of the Cygnus Loop, a supernova remnant in the summer Milky Way.


Evalutating Your Choices
The Tele Vue 76 is a fine choice for observers who require both high quality and extreme portability. It's easy to lug around without taking over your luggage. Drawbacks for some may include its fairly expensive price and the limited light gathering ability inherent in any 3-inch objective lens. But the high-quality telescope will deepen your appreciation of the wonders found in the night sky.

翻译一下，我英文不好，太专业了。

有趣的是作者提到与76MM TAKAHASHI (假设是FC-76) 做了比较，但既没有过程，也没有结论，似乎忘了这回事，或是在编辑时删去了?
没有比较，使可读性降低不少。