astro-tech
www.astronomytechnologies.com
from Astronomy Technologies, 680 24th Avenue SW, Norman, OK 73069
© 2007 by Astronomy Technologies
Specifications, features, and descriptions are effective 7/1/2007, but are subject to correction and/or modification without notice and/or obligation.
Your
Astro-Tech AT66ED
refractor is usable for day and night
viewing, simply by adding a 1.25” star diagonal and eyepiece. Any
brand of 1.25” eyepiece can be used, from a 40mm for the lowest
possible magnification (10x), down to a 3mm (133x) for high power
use. Removing the Astro-Tech’s 1.25” eyepiece holder reveals a
Schmidt-Cassegrain rear cell thread on the focuser drawtube, allowing
you to add a thread-on SCT-type 2” diagonal for 2” eyepiece use.
The focal length of the AT66ED is ideal for low to medium power
wide-angle views of nebulas, open star clusters, large galaxies, and
comets. Crisp views of the Moon and planets are also routine at
magnifications of 100x to 133x when seeing conditions permit.
To calculate the magnification of your telescope and eyepiece
combination, divide the telescope focal length in mm by the eyepiece
focal length in mm. For example, a 4mm eyepiece in the AT66ED will
give you a magnification of 100x (400mm/4mm = 100).
Astronomical Observing:
The theoretical maximum usable power
available from this telescope is 133x, although this requires a 3mm
eyepiece that provides a narrow and dim 0.5mm exit pupil. A more
practical maximum magnification for astronomical viewing with the
AT66ED would be 100x, using a 4mm 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 133x. Under less
than ideal conditions, lower powers in the 65x to 100x range provide
more consistently usable and pleasing images.
The widest possible field of view with a 1.25” eyepiece is about
4.2°, which can be achieved with a 10x (40mm) Plössl eyepiece.
While the AT66ED has not been specifically designed for astro-
photography, it does an outstanding job as a wide-field astrograph
for casual 35mm and CCD imaging. A chrome thumbscrew under the
focuser lets you lock in a sharp focus for photography.
The focuser can be rotated a full 360° for the best photographic
composition, or to put the star diagonal in the most comfortable
observing position. Loosening the knurled lock ring on the scope
barrel by turning it counterclockwise lets you rotate the focuser. Turning
the ring back clockwise locks the focuser at the chosen angle.
Terrestrial Observing:
The AT66ED works well for daytime birding,
nature studies, sweeping the landscape from the home with a view,
etc. It is also a very good 400mm (8x) f/6 telephoto lens for terrestrial
photography. Generally speaking, the maximum usable daytime power
with any terrestrial scope is about 1x per mm of aperture (67x for the
AT66ED with a 6mm eyepiece). Attempts to push the daytime power
beyond this point often magnify the heat waves, dust, and “mirage” in
our atmosphere to the point where the images become blurry and
unusable. A 40x (10mm) to 50x (8mm) eyepiece is usually more
satisfying for everyday high power terrestrial use than a 67x eyepiece.
Mounting the AT66ED:
A stable tripod or astronomical mount is
essential for best viewing. The AT66ED is light enough to be used on
any good quality camera tripod with a 7 to 8 pound payload capacity.
The scope’s L-shaped mounting foot has two 1/4”-20 thread holes
for direct connection to a standard photo tripod head. The front
mounting hole provides a better balance when the scope is used
with a 1.25” star diagonal and eyepiece. The rear mounting hole
provides a better balance when the scope is used with a heavier 2”
diagonal and eyepiece, or a camera.
The mounting foot is shaped like the dovetail used to connect optical
tubes to the Astro-Tech Voyager altazimuth, Celestron CG-5 Advanced
Series, Meade LXD-75, and Vixen Sphinx and Great Polaris German
equatorial mounts. This allows you to install the AT66ED directly on
any of these mounts with no other adapter required.
Optional Astro-Tech Accessories:
The adjustable-height Astro-
Tech Voyager altazimuth mount has automatic-clutch worm gear
manual slow motion controls in both altitude and azimuth to make
tracking terrestrial and astronomical objects smooth and easy. The
Astro-Tech 1.25” star diagonal has state-of-the-art 99% reflectivity
dielectric coatings to provide the maximum brightness and planetary
detail contrast possible from your AT66ED. The Astro-Tech 45° image-
erecting 1.25” diagonal is available to provide correctly-oriented
terrestrial images. An inexpensive Astro-Tech non-magnifying
multireticle illuminated finder is also available for your AT66ED.
Caring for Your Scope Optics:
Never store the telescope in a
damp or humid environment. Avoid leaving it in a hot environment
(exposed to direct sunlight on a window sill, 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 which
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, clean the lens as follows.
First, 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). Using canned or compressed
air is not recommended, as the propellant in the can may spit out and
leave difficult-to-remove deposits on the lens. Also, the expanding
compressed air drops in temperature as it leaves the can. The cold
air coming out of the tiny tube that most compressed air cans use to
direct the air flow has been known to chill a lens to the point of cracking
the glass if pointed at the same spot on the glass for too long.
Second, moisten a cloth with a few drops of a photographic-quality
optical cleaning solution designed for multicoated camera and
binocular lenses. A well-worn cotton handkerchief works well and
Zeiss and Kodak make suitable lens cleaning fluids. Do not drip the
cleaning fluid directly on the lens. Use the barely damp (not wet)
cloth to gently wipe the lens surface 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. Start with 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 (which are 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.
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:
Depending on the tube color, the
AT66ED is either fully anodized or finished in a combination of durable
paint and a liquid-anodize high gloss finish. The painted surfaces will
rarely show dirt or fingerprints. If they do, a clean soft cloth slightly
dampened with plain water should be enough to clean them.
The very durable anodized surfaces can be easily smudged with
fingerprints, but these will not harm the anodized finish. As with the
painted areas, 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 clean the surface. 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 the telescope in the rain or in conditions where it may
get wet. The telescope is not waterproof. If the telescope accidentally
gets caught in the rain, immediately wipe off all water using a clean
and dry soft cloth. If the 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.
Caution! Never directly view the Sun with your telescope!
Never
aim your AT66ED at the Sun without having a professionally-
manufactured solar filter mounted over the objective lens. Viewing
the Sun through the scope without the proper protection for even a
moment may result in permanent severe damage to your eyes, and
can even cause blindness. Contact your Astro-Tech dealer if you are
interested in purchasing a compatible professional solar filter.
