Astro-Tech AT80EDT Apochromatic Refractor.

This Astro-Tech AT80EDT refractor has:
• 80mm f/7 fully multicoated triplet apochromatic optics using an ED element and all Ohara
glass
• light weight/high strength carbon fiber body
• collimatable lens cell
• dual-speed 2" Crayford focuser with 10:1 ratio fine focusing
• both 2" and 1.25" brass compression ring eyepiece holders
• retractable lens shade/dew shield with lock knob
• split mounting rings for installing on a German equatorial mount
• aluminum-frame shipping/storage hard case
• two-year warranty

Astro-Tech uses only premium Ohara glass and state-of-the-art optical multicoatings in the
apochromatic ED triplet optics of the AT80EDT. This results in images that are essentially
totally free of the annoying halo of unfocused violet light (chromatic aberration) that mars the
bright-object images of lesser scopes, despite the fast focal ratio, and even at very high
magnifications.

A Sky & Telescope review said the AT80EDT’s “essentially textbook-perfect diffraction
images of brilliant white stars showed a touch of green fringing outside of focus and magenta
inside. The in-focus images were clean, crisp, and color free. Indeed, observing with a 3-mm
eyepiece (187x), I easily spotted Mars’s polar cap and several surface features on the
planet’s small, 7-arcsecond-diameter disk. Likewise, the Cassini division of Saturn’s rings
was moderately easy to see despite the ring systems low angle. And the double star Rigel in
Orion was a breeze to split in a sky still bright with evening twilight."

The Sky & Tel review continued, “One of my favorite eyepieces with the scope is the TeleVue
17-mm Nagler Type 4. Yielding 33x, a field 2½° across, and sharp stars edge to edge, this
setup is perfect for cruising the Milky Way. I counted scores of star clusters during a casual
sweep from Auriga to Cassiopeia . . . Stars appeared appeared sharp and round across an
image circle about 21mm in diameter, which, at the scope’s 560-mm focal length, covers 2.1°
of sky. Daytime photographs are contrasty and free of color fringes, even with challenging
subjects like tree branches against a bright, blue sky. Since the OTA weighs just 5.7 pounds
(2.6 kg), the AT80EDT is an ideal travel scope, and one that I’d welcome for observing and
photography at any solar eclipse."

These exceptional Astro-Tech optics are even more impressive when you consider the
package they come in. The Astro-Tech AT80EDT has an advanced light weight/high strength
carbon fiber body and dew shield. Carbon fiber is the material being used for most of the body
structure of the new Boeing 787 Dreamliner passenger jet, so you know that carbon fiber has
an outstanding strength to weight ratio. The Astro-Tech AT80EDT has a dual speed 2"
Crayford focuser with a microfine 10:1 fine-focusing ratio. The supplied 2" and 1.25" eyepiece
holders use non-marring brass compression rings that won’t scratch your star diagonal or
eyepiece barrels. The AT80EDT has a retractable carbon fiber lens shade with a lock knob
and comes in a locking aluminum-frame hard shipping/storage case. It has dual split
mounting rings that fit directly onto a wide variety of German astronomical mounts.

This feature-laden 80mm Astro-Tech AT80EDT ED triplet apochromatic refractor is priced
hundreds of dollars less than competitive 80mm triplet scopes – and even less than many
competitive doublet systems! At the sensationally low price for an apochromatic triplet in a
state-of-the-art carbon fiber body, and for the exceptional performance you get, the AT80EDT
is surely one of the best buys in the astronomy!

Features of this telescope . . .

ED apochromatic triplet refractor optics: 80mm (3.1") aperture, 560mm focal length, f/7 focal
ratio three-lens optical system using an ED (Extra-low Dispersion glass) element to reduce
spurious color halos and fringing to vanishingly low levels. All three lens elements are
precision ground and polished under computer control from the finest quality Ohara glass.
Ohara is well-known as Japan’s premier manufacturer of specialized optical glass.

Fully multicoated optics: The AT80EDT triplet objective lens has the latest state-of-the-art
antireflection multicoatings on all air-to-glass surfaces for high light transmission and
excellent contrast. This can easily be seen by looking into the objective lens of the scope.
Virtually no reflection of your face will be seen. It’s a sure sign that the high transmission
coatings are doing their job, by letting virtually all the light enter the scope, rather than
reflecting some light back to your eye.

Collimatable lens cell: The push/pull lens cell is fully collimatable in the field for peak
performance. A simple optional Cheshire eyepiece and your own eyes are all you need.

Internal light baffles: Contrast-enhancing internal knife-edge light baffles, a glare-reducing
baffle at the front of the dew shield, and a specially darkened tube interior provide truly dark
sky backgrounds and high terrestrial contrast. The edges of the lenses are blackened to
reduce internal reflections and further improve image contrast.

Tube finish: The optical tube and dew shield of the AT80EDT are made of multiple layers of
high strength woven carbon fiber cloth encapsulated in a transparent high gloss epoxy. This
space-age material trims nearly a pound off the weight of the AT80EDT’s aluminum tube
predecessor, while still being dent-proof and exceptionally strong. The herringbone weave of
the carbon fiber cloth is easily seen through its clear epoxy coating. The narrow alternating
light and dark stripes of the weave seem to reverse their shades from light to dark and back
again as you move the tube. The carbon fiber cloth is laid down by hand during the
manufacturing process, so a subtle seam along the length of the tube is typically visible
where the edges of the herringbone weave cloth meet. The focuser and metal trim are black
anodized.

The self-storing retractable carbon fiber dew shield slows the formation of dew on the lens
in cold weather to extend your undisturbed observing time. It also improves the contrast,
similar to the effect of the lens shade on a camera lens, when observing during the day or
when there is excessive ambient light at night, such as a neighbor’s backyard security light.
The tube measures a compact 19" long with the dew shield retracted (22" long with it
extended). A lock knob built into the dew shield lets you lock the firmly in place so it can’t
slip while aiming at the zenith.

The carbon fiber tube and dew shield have excellent thermal characteristics. The dew
shield is oversized, with a 124mm o.d. compared to the 80mm lens diameter and 90mm tube
diameter. This assures that tube currents, which typically follow the walls of a telescope
tube, will be out of the converging 80mm light path for the most part and will have only a
minimal effect on your images as the AT80EDT cools down to ambient temperature. You can
begin serious observing sooner with an AT80EDT than you can with an aluminum tube 80mm
triplet with a conventional dew shield design.

Dual speed microfine 2" Crayford-style focuser: The precision-made no-backlash focuser has
dual-speed focusing. There are two coarse focusing knobs. The right knob also has a smaller
concentric knob with 10:1 reduction gear microfine focusing ratio. This provides exceptionally
precise image control during high magnification visual observing and critical 35mm or CCD
imaging. The focus knobs have ribbed gripping surfaces so they are easy to operate, even
while wearing gloves or mittens in cold weather. A knob underneath the focuser lets you
adjust the tension on the drawtube to accommodate varying eyepiece/photo accessory loads,
while a second knob firmly locks in your photographic focus.

Long focuser travel: The long 80mm (3.1") travel focuser drawtube helps keep the overall
scope length as short as practicable for convenient travel and storage. The tube measures
only 19" long with the lens shade retracted, and 22" long with it extended. The drawtube has
a scale marked in centimeters subdivided in 1mm increments and in inches subdivided in
1/16th inch increments. This lets you note individual focuser positions for easy return to the
correct focus when switching between visual use and photography. A lock knob underneath
the focuser lets you lock in your photographic focus.

Compression ring eyepiece holders: The focuser’s drawtube terminates in a 2" eyepiece
holder that uses a non-marring soft brass compression ring to hold a 2" star diagonal and/or
accessories in place. The compression ring won’t scratch the barrel of your star diagonal and
accessories as an ordinary thumbscrew can.

A supplied 1.25" accessory adapter slips into the 2" eyepiece holder to let you use a 1.25"
star diagonal, image erecting diagonal, or photographic accessories. Like the 2" eyepiece
holder, the 1.25" adapter also uses a non-marring soft brass compression ring to hold 1.25"
star diagonals and accessories in place. If you are partial to 1.25" eyepieces and need an
outstanding diagonal for this scope, consider the 99% reflectivity Astro-Tech 1.25" dielectric
diagonal #AT1D. It's a Sky & Telescope Hot Product for 2007.

An Astro-Tech 2" dielectric star diagonal #AT2D will give you the same 99% reflectivity
performance with 2" eyepieces.

Mounting rings: The AT80EDT has two 90mm felt-lined hinged split mounting rings to allow
you to install the scope on any of a number of German equatorial mounts directly, or on a
telescope mount dovetail plate, such as one of those from Losmandy or Vixen. The rings are
drilled and tapped with 1/4"-20 thread holes on the top as well as the bottom so you can
mount an accessory plate on top of the AT80EDT.

Finderscope mounting holes: There are two holes drilled and tapped in the focuser at the 10
o’clock and 2 o’clock positions. These allow the installation of an optional red dot finder, such
as the Astro-Tech #ATF illuminated multiple reticle finder, on the most comfortable side of the
scope for the way you view. The holes are sealed by screws if no finder is installed, to prevent
the entrance of dust into the focuser.

Shipping/storage case: The scope comes in a locking 23.5" x 7.5" x 9" aluminum-frame
foam-lined hard shipping/storage case with carry handle. Astro-Tech is one of the very few
manufacturers to provide a case at no charge for protection during shipping and as a storage
convenience when the scope is not in use. Unfortunately, FedEx, UPS, and the Postal
Service are very good at treating packages roughly. Occasionally, your scope can arrive in
perfect condition, but with the walls of the shipping case dented in transit from rough
handling, or the aluminum frame sprung, rendering the appearance of the case less than
pristine. Damage to the shipping case in such instances is not covered by warranty.

Two year warranty: As an expression of the confidence Astronomy Technologies has in the
quality of their products, the Astro-Tech AT80EDT triplet apo is protected by a two-year
limited warranty against flaws in materials and workmanship (shipping case excluded).
The Sky & Telescope review concluded, “Because of their versatility for casual and serious
observing, as well as day and night photography, there are lots of reasons to like today’s 80
-mm short-focus refractors. The AT80EDT wraps many of their best features into a neat,
compact, attractively priced package."

Supplied Accessories:
Split and hinged felt-lined mounting rings; dust covers; carbon fiber body; self-storing carbon
fiber dew shield with lock knob; 2" dual speed Crayford-style focuser with 2” and 1.25” brass
compression ring eyepiece holders; aluminum-frame hard case.

See The Review In The September 2008 Issue Of Sky & Telescope.

Price - £469.00 + £10.00 shipping & insurance.

The Astronomy Shop

1 Tone Hill. Wellington

Somerset TA21 0AU

United Kingdom

Telephone: +44 (0)1823 665510