Astro-Tech AT8 IN Quick Start Manual

astro-tech A T 8 IN
8" f/4 Imaging Newtonian from Astronomy Technologies
Thank you for choosing the 8" f/4 Astro-Tech AT8IN
imaging Newtonian optical system.
Unique baffling, a fast focal ratio, and a large aperture
optimize your AT8IN for short exposure, high contrast,
wide field deep space imaging. You can use a 35mm
camera, DSLR, web-cam, DSI-type camera, or a large
THE PARTS OF YOUR AT8IN
8 x 50mm finder
in quick-release
bracket
2" dual-speed
Crayford
focuser
Aperture .................................................... 200mm (8")
Focal Length .................................................... 800mm
Focal Ratio ............................................................... f/4
Optical Type .................................. Newtonian reflector
Mirrors .... B270 "water white" optical crown glass (BK7
equivalent), aluminized and overcoated with quartz
Baffle System ................ 15 internal knife-edge baffles
Diagonal Mirror Obstruction ................... 70mm m.a.,
35% by diameter, 12.25% by area
Resolving Power
(Dawes' Limit)
Limiting Magnitude
(visual)
Tube Diameter ............................... 8.98" (228mm) o. d.
Mounting the AT8IN: Die-cast aluminum hinged split tube mount-
ing rings are standard equipment. Each ring has a flat boss on its
underside with a 1/4"-20 thread mounting hole for installing the ring
on a Losmandy-style "D-plate" or Vixen-style dovetail mounting plate.
This lets you mount the scope on virtually any equatorial mount. The
1/4"-20 hole is flanked by two 4mm metric holes on 30mm centers.
In addition, there is a flat boss with a 4mm metric hole on the top of
each ring. This allows you to install a separate dovetail rail on top of
the optical tube for mounting photoguide rings and a guidescope or
similar accessories piggyback on top of the AT8IN. Loosening the
locking knobs on the cradle rings allows the optical tube to rotate in
the felt-lined rings to bring the focuser and finder to the most com-
fortable operating position.
At a weight of just under 22 pounds with rings and finder, your
AT8IN requires a stable equatorial mount with a minimum payload
capacity of 30 pounds or greater.
2" x 35mm
extension
tube
Astro-Tech AT8IN Imaging Newtonian Specifications
.......... 0.58 arc seconds
..................... 14 maximum
format CCD camera. Excellent deep space visual observ-
ing is also possible with 1.25" and 2" eyepieces, as is
very acceptable solar system observing and imaging.
Please use this instruction sheet to familiarize yourself
with your scope's parts and functions before operating it
for the first time.
8 x 50mm finder in
quick-release bracket
Mounting bosses for optional
accessory dovetail
Spider vanes
(2 of 4)
Tube
rings
Secondary
collimation
screws
Dust
cap
1.25" accessory
adapter
Battery pack
for mirror fan
Tube Length
(including collimation knobs)
Tube Weight ....................... 18 lbs. (8.18 kg) tube only;
21.6 lbs. (9.82 kg) with rings and finder
Tube Mounting System ....... dual 9" hinged split rings;
one 1/4"-20 mounting hole on bottom, flanked by two
4mm metric holes; and one 4mm metric hole on top
Focuser ... 34mm (1.35") travel 2" dual-speed Crayford
with 2" compression ring accessory holder
Finderscope .......... 8 x 50mm in quick-release bracket
Supplied accessories ............. 1.25" compression ring
accessory holder, 2" diameter by 35mm long focuser
drawtube extension, cooling fan with battery pack
The Crayford Focuser: The backlash-free Crayford focuser has
dual-speed focusing. There are two coarse focusing knobs, as shown
in the illustration on the next page. One knob also has a smaller
concentric knob with a 10:1 reduction gear for microfine focusing.
The focuser drawtube terminates in a non-marring 2" compression
ring accessory holder. A 35mm long x 2" diameter compression ring
extension tube is provided to match different back focus requirements
for visual and photographic use. Additional optional Astro-Tech ex-
tension tubes in 35mm, 50mm, and 80mm lengths are available from
your Astro-Tech dealer to accommodate any other back focus require-
ments you might have. A 1.25" compression ring accessory adapter
is supplied to hold 1.25" eyepieces and camera adapters.
The 35mm extension tube and the 1.25" adapter are both threaded
to accept standard 2" light pollution or color filters. The 2" focuser
drawtube and 35mm extension tube have internal anti-reflection
threading to improve contract.
2" accessory
holder
1.25"
accessory
adapter
Tube ring
lock knob
Primary mirror
center spot donut
...... 32" (812mm)
Focus
knob