Refractors

More Information  · Supplied Accessories  · Recommended Accessories  · Images of Some Features Price $699.00 Shipping $19.95 Highest Useful Magnification 187x Visual Limiting Magnitude 12.0 Focal Length 560mm Focal Ratio f/7 Resolution 1.45 arc seconds Aperture 3.1" Weight 7.8 lbs. Warranty 2 years

• 80mm f/7 fully multicoated triplet apochromatic optics using an ED element and all Ohara glass
• split tube body design for binoviewing without a Barlow
• dual-speed rotating 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 ring 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 AT80EDTA. 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.

These are the same optics that are used in the 80EDTA’s carbon-fiber tube brother, the AT80EDT. A September 2008 Sky & Telescope review said of that scope that its “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 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."

The original September Sky & Tel review inadvertently gave the Astro-Tech 80mm triplet optics a three-star rating, despite all of the review’s glowing comments. However, the error was soon corrected by Sky & Tel on page 14 of their October, 2008, issue when the magazine said “Due to a production error, The S & T Rating for the AT80EDT refractor (September issue, page 39) should be four stars, not three." We appreciate the Sky & Tel correction that gives the Astro-Tech 80mm triplet optics the real four-star rating that its optics so rightly deserve.

    Those exceptional Astro-Tech optics are even more impressive when you consider that this feature-laden 80mm Astro-Tech 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, and for the exceptional performance you get, the AT80EDTA 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 AT80EDTA 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.

• Internal light baffles: Contrast-enhancing internal knife-edge light baffles and a specially flocked and 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 design: The optical tube of the AT80EDTA is made of two aluminum tube sections threaded together. You can unthread and remove one of the tube sections to reduce the body length of the AT80EDTA by 4.3". This lets you use a binoviewer at low powers in the AT80EDTA, without having to use a Barlow lens or image amplifier to reach focus as you have to do with other scopes. Using a Barlow in a binoviewer increases the magnification, reduces image brightness, and reduces the field of view, often rendering nebula and lunar vistas somewhat less than awe-inspiring. With the AT80EDTA in its binoviewer mode, you can see clear wide-angle binoviewer vistas that are unobtainable with other scopes that need a Barlow for the binoviewer to focus.

• Retractable dew shield: The self-storing retractable 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 18.9" long with the dew shield retracted (21.6" long with it extended), and a very short 14.5" with the dew shield retracted in the binoviewer mode (17.2" with it extended). A lock knob built into the dew shield lets you lock it firmly in place so it can’t slip while aiming at the zenith.

• Dual speed microfine rotating 2" Crayford-style focuser: The precision-made no-backlash gearless 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 on the top of the focuser allows you to rotate the focuser a full 360°. This lets you rotate the focuser to line up a camera in either a landscape or portrait orientation (or any orientation in between), as well as put a star diagonal and eyepiece into the most comfortable observing position, and then temporarily lock the focuser in that position.

• 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. As mentioned above, the tube is only 18.9" long with the dew shield retracted in its standard configuration (21.6" long with it extended). The drawtube has a scale marked in centimeters subdivided in 1mm increments. This lets you note individual focuser positions for easy return to the correct focus when switching between visual use and photography. A knob underneath the focuser lets you adjust the tension on the drawtube to accommodate varying eyepiece/photo accessory loads, as well as firmly lock in a 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 ring: The AT80EDTA has a felt-lined hinged split mounting ring with three 1/4"-20 thread holes to allow you to install the scope on any of a number of German equatorial mounts directly. You can also attach the ring to an optional dovetail plate, such as one of those from Losmandy or Vixen, and use the scope on the wide variety of equatorial and altazimuth mounts with heads that use a Losmandy or Vixen-style quick-release dovetail mounting system.

• Finderscope mounting hole: There is a hole drilled and tapped into the focuser at the upper left front. This allows the installation of an optional red dot finder, such as the Astro-Tech #ATF illuminated multiple reticle finder. The hole is sealed by a recessed screw if no finder is installed, to prevent the entrance of dust into the focuser.

• Shipping/storage case: The scope comes in a locking 22.5" 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 AT80EDTA triplet apo is protected by a two-year limited warranty against flaws in materials and workmanship (shipping case excluded).