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SPECIFICATIONS
Specifications:

ETX-90AT Astro Telescope

Optical design . . . . . . . . . . . . . . . . . . . . Maksutov-Cassegrain
Primary mirror diameter . . . . . . . . . . . . . . . . . . . 96mm (3.78”)
Clear aperture. . . . . . . . . . . . . . . . . . . . . . . . . . . . 90mm (3.5”)
Focal length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1250mm
Focal ratio (photographic speed). . . . . . . . . . . . . . . . . . . f/13.8
Near focus (approx) . . . . . . . . . . . . . . . . . . . . . . 11.5 ft (3.5m)
Resolving power. . . . . . . . . . . . . . . . . . . . . . . . . . 1.3 arc secs
Super multi-coatings (EMC). . . . . . . . . . . . . . . . . . . . standard
Limiting visual stellar magnitude (approx.) . . . . . . . . . . . . 11.7
Image scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.16°/inch
Maximum practical visual power . . . . . . . . . . . . . . . . . . . 325X
Optical tube dimensions
(dia. x length). . . . . . . . . . . 10.4cm x 27.9cm (4.1” x 11”)
Viewfinder. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 x 21mm
Secondary mirror obstruction (dia.; %) . . 27.9mm (1.1”); 9.6%
Telescope mounting. . . . . . . . . . . . . . . . fork type; double tine
Setting circle diameters . . . . . . . . . . . . . . . Dec.: 3.5”; R.A.: 7”
Input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 volts DC
MotorDrive System DC servo motors

with encoders,both axes

Bearings:
Altitude. . . . . . . . . . . . . . . . . . . . . . . UHMW polyethylene
Azimuth. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . PTFE
Materials:
Tube body. . . . . . . . . . . . . . . . . . . . . . . . . . . . . aluminum
Mounting . . . . . . high-impact ABS, aluminum-reinforced
Primary mirror. . . . . . . . . . . . . . . . . . . . . . . . Pyrex®glass
Correcting lens . . . . . . . . . . . BK7 optical glass, Grade-A
Telescope dimensions:
. . . . . . . . . . . . . . . . 38cm x 18cm x 22cm (15” x 7” x 9”)
Telescope net weight:
(incl. Autostar & batteries) . . . . . . . . . . . . 3.5kg (7.8 lbs)
Telescope shipping weight. . . . . . . . . . . . . . . . 5.8kg (12.8 lbs)
Battery Life (approx.):
with Autostar. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 hrs
Specifications:

ETX-105AT Astro Telescope

Optical design . . . . . . . . . . . . . . . . . . . . Maksutov-Cassegrain
Primary mirror diameter . . . . . . . . . . . . . . . . . . 116mm (4.56”)
Clear aperture. . . . . . . . . . . . . . . . . . . . . . . . . . 105mm (4.13”)
Focal length . . . . . . . . . . . . . . . . . . . . . . . . . . 1470mm (57.8”)
Focal ratio (photographic speed) . . . . . . . . . . . . . . . . . . . . f/14
Near focus (approx). . . . . . . . . . . . . . . . . . . . . . . . 4.6m (15 ft)
Resolving power. . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 arc secs
Super multi-coatings (EMC). . . . . . . . . . . . . . . . . . . . standard
Limiting visual stellar magnitude (approx.) . . . . . . . . . . . . 12.1
Image scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.99°/inch
Maximum practical visual power. . . . . . . . . . . . . . . . . . . . 420x
Optical tube dimensions
(dia. x length) . . . . . . . . 12.4cm x 32.8cm (4.88” x 12.9”)
Viewfinder. . . . . . . . . . . . . . . . . . . . . . . . 8 x 25mm right-angle
Secondary mirror obstruction (dia.; %). . . 3.3cm (1.32”); 9.4%
Telescope mounting. . . . . . . . . . . . . . . . fork type; double tine
Setting circle diameters. . . . . . . . . . . . . Dec.: 3.81”; R.A.: 7.8”
Input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 volts DC
Motor Drive System. . . DC servo motors with encoders, both axes