Astro-Tech AT72ED II Quick Start Manual page 2

Astronomical Observing: The theoretical maximum usable
power available from this telescope is 144x, although this requires
a 3mm eyepiece that provides a narrow and dim 0.5mm exit pupil.
Still higher power is occasionally possible, given excellent seeing
conditions. 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 144x or higher. Under less than ideal conditions,
lower powers in the 72x to 108x range provide more consistently
usable and pleasing images.
The widest practical field of view with a 1.25" eyepiece is about
4°, which can be achieved with an 11x (40mm) TeleVue Plössl
eyepiece. A 2" wide field eyepiece such as the 40mm Explore
Scientific 68° or TeleVue 41mm Panoptic will deliver an immense
field of view (6.3° @ 10.8x with the Explore Scientific and 6.45°
@ 10.5x with the TeleVue), making the AT72ED II its own best
finderscope when used with either of these eyepieces.
The AT72ED II also does an outstanding job as a wide-field
astrograph for DSLR and CCD imaging. A mm scale on the focuser
drawtube lets you note and quickly return to the best photographic
focus, while a chrome lock knob under the focuser lets you lock
in that sharp focus.
Terrestrial Observing: The AT72ED II works very well for
daytime birding, nature studies, sweeping the landscape from the
home with a view, etc. It is also a very good f/6 432mm (8.6x)
telephoto lens for terrestrial photography. Generally speaking, the
maximum usable daytime power with any terrestrial scope is about
1x per mm of aperture (72x with a 6mm eyepiece). Attempts to
push the daytime power higher often magnify the heat waves,
dust, and "mirage" in our atmosphere to the point where the
images become blurry and unusable. A 17x (25mm) to 54x (8mm)
eyepiece is usually more satisfying for everyday terrestrial use than
a 72x eyepiece.
Mounting the AT72ED I I: A stable photo tripod or astronomical
mount is essential for best viewing. The 4.65 pound AT72ED II is
light enough to be used on any good quality camera tripod with a
minimum payload capacity of 7 to 8 pounds. The scope's supplied
Vixen-style dovetail has a 1/4"-20 thread hole for direct connection
to a standard photo tripod head.
Finder Mounting Points: There are four mounting holes on
the focuser available for installing an optional finder (such as the
optional Astro-Tech illuminated multiple reticle finder or the Astro-
Tech 8x50mm right angle dark crosshair finder). The mounting
hole positions (two per side) are shown on the illustration on the
front page. The holes are sealed by hex head bolts when no finder
is installed.
Camera Angle Adjuster (CAA): The AT72ED II is equipped
with a combined camera angle adjuster/2" accessory holder. To
rotate the CAA to adjust the camera angle for the best photographic
composition, loosen the chrome lock knob at the side of the CAA
body (shown in the illustration on the front page). Rotate the CAA
to the desired angle and tighten the lock knob to hold it in position.
There are five Teflon rotation tension screws around the rotation
mechanism. If the rotation is too stiff or becomes loose due to use
or temperature extremes, you can adjust these screws slightly and
evenly to tailor the rotation tension to suit your preference. These
should rarely need adjustment, however, and should be turned only
in small increments. Excessive or uneven tightening of these screws
can damage them, a problem not covered by warranty.
A chrome lock knob under the rack-and-pinion focuser body lets
you lock the focuser drawtube at a sharp focus for photography.
Optional Astro-Tech Accessories: The adjustable-height
Astro-Tech Voyager I I altazimuth mount has worm gear manual
slow motion controls in both altitude and azimuth to make tracking
terrestrial and astronomical objects smooth and easy. The Astro-
astro-tech
© 2017 by Astronomy Technologies
www.astronomytechnologies.com
from Astronomy Technologies, 680 24th Avenue SW, Norman, OK 73069
Specifications, features, and descriptions are effective 11/1/2017, but are subject to correction and/or modification without notice and/or obligation.
Tech 1.25" and 2" star diagonals have state-of-the-art 99%
reflectivity dielectric coatings to provide the maximum brightness
and planetary detail and contrast possible from your AT72ED II.
45° viewing angle image-erecting 1.25" diagonals are available to
provide correctly-oriented terrestrial images.
Caring for Your Scope Optics: Never store your telescope in a
damp or humid environment. Avoid leaving it in a hot environment
(exposed to direct sunlight on a windowsill, in a car trunk, etc.) If
you must store it in high humidity conditions, put a few packets of
desiccant (silica gel or the equivalent, available from most camera
stores) in with the telescope to absorb excess moisture. If not
properly stored in a humid environment, the telescope may develop
mildew that can damage the optics.
If dew has formed on the scope after a night's observing, allow
the scope optics to air dry at room temperature before putting the
lens cover on the scope and storing it away.
If the front lens surface becomes dusty, smeared, or shows
fingerprints or any other surface build-up, you can clean the lens
as follows. Gently blow away any surface dust or particles with a
clean air blower (a child's ear syringe or a photographer's camel's
hair brush with attached blower bulb, for example).
Moisten a soft cloth with a few drops of an optical cleaning
solution designed for multicoated camera and binocular lenses. A
well-worn cotton handkerchief works well and Canon, Nikon, and
Zeiss make suitable lens cleaning fluids. Do not drip cleaning fluid
directly on the lens. Use the barely damp (not wet) cloth to gently
wipe the lens clean, turning the cloth frequently to always keep a
clean portion of the cloth in contact with the lens.
Blot the lens dry with a dry portion of the cleaning cloth or a
separate cloth. Use a clean cloth each time cleaning is needed.
Avoid overcleaning your scope. The multicoatings on the lens are
quite hard and durable. However, frequent overzealous cleaning
can scratch the coatings if all the dust particles (often tiny flecks
of windborne rock) are not removed before you start pushing a
damp cloth around the lens surface. A few specks of debris on the
lens will not be visible in your images, as they are not in the focal
plane and don't block enough light to measure, let alone be seen.
Fingerprints should always be cleaned off promptly, however,
as they can etch the coatings on your lens if not removed before
storing your scope.
As a rule, though, clean your optics only when absolutely
necessary. If you take proper care of your scope, cleaning should
rarely be needed.
Caring for Your Scope Finish: Your AT72ED II is finished in
baked-on automotive paint, with portions hard anodized. These
very durable surfaces can become smudged with fingerprints during
use, but these will not harm the finish. A clean soft cloth slightly
dampened with plain water (or a little moisture from your breath
and a quick wipe with a clean handkerchief) is generally enough to
remove the fingerprints. Avoid harsh chemical cleaners or organic
solvents like benzene, alcohol, etc., as these may ruin the finish.
They can certainly affect the optical coatings if they accidentally
drip or splash on the objective lens.
Never use your AT72ED II terrestrially in the rain or in conditions
where it may get wet. Your telescope is not waterproof. If your
scope accidentally gets caught in the rain, immediately wipe off
all water using a clean and dry soft cloth. If your telescope gets
totally soaked in water, or submerged, immediately contact your
dealer for service instructions. Do not disassemble or attempt to
repair your telescope yourself, as this violates the warranty terms
under the limited product warranty, and negates any guarantee.