AT102ED - First light
I received my AT102ED earlier this week and achieved first light last night under a partly cloudy, somewhat hazy sky with seeing that ranged from mediocre to pathetic.
Initial impressions of the scope are quite positive: It looks good, is fairly light, and can be mounted on a smallish alt-az or equatorial affording good stability and grab-and-go capability. I mounted the scope on an Orion VersaGo II with home-made maple legs substituting for the thin aluminum originals. The short damping time allowed for the easy use of high powers. The gloss white tube has a few minor irregularities visible on close examination, but at the telescope's price point, is satisfactory. The r@p focuser has a nicely calibrated draw tube with smooth motion over most of its range, but there is a glitch once every rotation of the coarse focus know where turning effort increases by about 50 percent. There is also some "wander" of the image unless the focuser is clamped to a high-effort setting. I'm trying to adjust the unit for better operation.
Optically, I would have to rate the AT102 as very good - about as capable as one might expect from an FPL-51 equivalent doublet. Color correction is adequate for visual use, but there is a slight red excess that shows at higher magnifications. Spherical aberration is well controlled.
My only disappointment was the view of Venus as it descended in the evening sky. The disc of the planet was very sharp at 89 and 119x, but the poor seeing conditions created annoying flashes of red and violet as the focus shifted.
Jupiter, however, was another story. In moments of decent seeing, the planet was loaded with high-contrast detail with many irregularities in the NEB, and well-defined Great Red Spot and RSH, and some fleeting details in both polar regions. All four Galilean moons were pinpoint sharp at powers from 119 to 143x.
Certainly, the image displayed somewhat superior contrast and color saturation with my Takahashi FC-100D, but the AT did acquit itself well and showed no visible false color.
Double star resolution of the AT proved to be excellent. Despite the poor seeing, the telescope easily and neatly resolved Epsilon Lyrae, Izar, RasAlgethi, Porrima, and the tough Delta Cygni. Airy discs were hard and sharp, and the delicate first diffraction rings at 143x showed good optical correction. However, orange or red stars did display an excess of red tint, the price to be paid for the scope's optical components.
Overall, the AT102ED is quite impressive for its low price point: Not perfect optically or mechanically, but a large step up from an achromat.
I'll be providing more observations in the future when the Western New York weather cooperates.