Astro-Tech AT8M Quick Start Manual

astro-tech
A T 8 M
Thank you for choosing the 8" f/12 Astro-Tech AT8M
Maksutov-Cassegrain catadioptric optical system.
The folded optics of your AT8M provides the high con-
trast and spurious color-free images typical of a costly
apochromatic refractor on solar system objects and the
brighter deep space objects, but at only a fraction the
cost of a premium refractor. Your AT8M images compare
quite favorably with those of 7" apochromatic refractors
THE PARTS OF YOUR AT8M
8 x 50mm finder
in quick-release
bracket
Dust cap
Aperture .................................................... 200mm (8")
Focal Length .................................................. 2400mm
Focal Ratio ............................................................. f/12
Optical Type .......... Rumak-type Maksutov-Cassegrain
Mirrors ............................................. BK7 optical glass,
aluminized and overcoated with quartz
Corrector Lens ............ BK7 optical glass, multicoated
Secondary Mirror Obstruction ..... 57mm in diameter,
Resolving Power
(Dawes' Limit)
Visual Limiting Magnitude .................... 14 maximum
Your Astro-Tech AT8M Maksutov-Cassegrain is usable for astro-
nomical viewing simply by installing it on a suitable mount and add-
ing a star diagonal and eyepiece. Any brand of eyepiece can be used,
from a 2" 55mm for the lowest practical magnification (44x) to a
7.5mm (320x) for very high power use. Both 2" and 1.25" accessory
adapters are supplied to let you use optional 2" or 1.25" star diago-
nals, image erecting diagonals, photo accessories, etc. A threaded
adapter that emulates the 2" rear cell thread of a Schmidt-Cassegrain
telescope is also included, to let you take advantage of the wide
variety of available visual and photographic SCT accessories.
The focal length of your AT8M is ideal for high resolution/high power
views of the Moon, planets, binary stars, and globular star clusters.
Excellent views of the brighter nebulas, galaxies, and comets are also
routine over a wide range of magnifications.
2" accessory
adapter
Astro-Tech AT 8M Maksutov-Cassegrain Specifications
38% by diameter, 14.4% by area
.......... 0.57 arc seconds
from Astronomy Technologies
five and six times the very reasonable AT8M price.
This instruction sheet will provide you with informa-
tion on how to get the most out of your new Maksutov-
Cassegrain, and how to properly maintain your telescope
so it can give you a lifetime of observing and imaging
enjoyment.
Please familiarize yourself with your scope's parts and
functions before operating it for the first time.
Collimation
screw covers
1.25" accessory adapter
SCT accessory adapter
Vixen-style dovetail
SCT accessory adapter
Tube Diameter ............................... 8.63" (220mm) o. d.
Tube Length
Tube Weight
Mounting System ........... 22" long Vixen-style dovetail
Focuser ............... 19-turn knob moving primary mirror
Finder .................... 8 x 50mm in quick-release bracket
Supplied adapters ....... 1.25" and 2" compression ring
accessory holders, plus SCT rear cell adapter
Lowest Usable Power ............... 44x (55mm eyepiece)
Highest Practical Power ........ 320x (7.5mm eyepiece)
Theoretical Maximum ............... 480x (5mm eyepiece)
To calculate the magnification of an eyepiece used with your AT8M,
divide the scope's focal length in mm by the eyepiece focal length in
mm. For example, a 15mm eyepiece in your AT8M will give you a
magnification of 160x (2400mm/15mm = 160).
Astronomical Observing: The theoretical maximum usable power
available from this telescope is 480x, although this requires a 5mm
eyepiece that provides a narrow and very dim 0.42mm exit pupil. A
more practical maximum magnification for astronomical viewing with
the AT8M would be 320x, using a 7.5mm eyepiece. Keep in mind that
seeing conditions play an important role in how high a magnification
you can use on any given night. Only very good seeing conditions
(clear skies and calm air) will support viewing at 240x and above.
Under less than ideal conditions, lower powers in the 100x to 150x
range provide more consistently usable and pleasing images.
8 x 50mm finder in
quick-release bracket
(with 2" accessory adapter)
(with 2" accessory adapter)
2" accessory
adapter
Focus
knob
1.25"
accessory adapter
.. 27.25" (692mm)
...... 22 lbs. (10 kg)