Astro-Tech AT72ED II Quick Start Manual

Thank you for choosing this Astro-Tech AT72ED II high-
quality compact ED doublet refractor.
The images from its f/6 ED (FPL-53 Extra-low Dispersion)
air-spaced doublet optics are virtually color-free. We believe
you'll find the optical performance of your AT72ED II to be
exceptional, particularly in view of its reasonable price.
USER-ADJUSTABLE PARTS OF THE AT72ED I I
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1.- 1.25" accessory adapter lock knob
2.- 2" accessory adapter lock knob (1 of 3)
3.- Rotating focuser grip ring
4.- Rotating focuser tension screws
(Teflon, 1 of 5)
5.- Rotating focuser lock knob
6.- Coarse focus knob
7.- Fine focus knob
8.- Focuser drawtube lock knob
(under focuser)
Astro-Tech AT72ED II Apochromatic Refractor Specifications
Aperture .................................................. 72mm (2.83")
Focal Length ....................................................432mm
Focal Ratio ...............................................................f/6
Objective Type .............................. air-spaced doublet,
with one element of FPL-53 ED glass
Optical Coatings ................................fully multicoated
Resolving Power
(Dawes' Limit)
Visual Limiting Magnitude .................. 11.8 maximum
Light Grasp
(versus the eye)
Lowest Usable Power ......~11x (with 40mm eyepiece)
Highest Terrestrial Power ...72x (with 6mm eyepiece)
Highest Practical Power ....108x (with 4mm eyepiece)
Theoretical Maximum .......144x (with 3mm eyepiece)
Your Astro-Tech AT72ED II refractor is usable for day and
night viewing, simply by adding an appropriate star diagonal or
image erector and an eyepiece. Any 1.25" or 2" eyepiece can be
used, from a 40mm or 41mm focal length for the lowest practical
magnification, to a 3mm for high power use.
The AT72ED II has a dual speed 2" rack-and-pinion focuser with
camera angle adjuster, a non-marring 2" compression ring accessory
adapter for use with 2" star diagonals, 2" eyepieces, or 2" photo
accessories. Also supplied is a 1.25" compression ring accessory
adapter for use with 1.25" star diagonals, terrestrial image erectors,
astro-tech AT 72ED I I
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9.- Mounting points for optional finder
(2 per side)
10.- Split hinged tube rings
11.- Vixen-style dovetail
12.- Retractable dew shield
13.- Focusing scale on drawtube
14.- 1.25" accessory adapter
15.- Compression ring
16.- Split tube ring mounting points
for
......... 1.61 arc seconds
.....................................106x
from Astronomy Technologies
This instruction sheet will provide you with information on
how to get the most out of your new telescope, and how to
properly maintain your telescope so it can give you a lifetime
of observing enjoyment.
Please familiarize yourself with your telescope's parts and
functions before operating it for the first time.
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options
Field Stops .... 2 glare-reducing baffles in optical tube,
plus 15 micro-baffles in the focuser drawtube
Focuser ........ dual-speed 2" rack-and-pinion, with 10:1
reduction ratio fine focus, camera angle adjuster,
and 1.25" and 2" compression ring accessory holders
Focuser Travel ....................................... 3.38" (86mm)
Lens Shade ..............................retractable, 88mm o.d.
Objective Lens Cover ............................. slip-on metal
Tripod Mount ... dual split rings, 6" Vixen-style dovetail
Tube Diameter ............................................84mm o. d.
Tube Length
Tube Length
Weight
(w/rings, dovetail, 1.25" adapter)
and 1.25" eyepieces and photo accessories.
The 432mm focal length of your AT72ED II is ideal for low to
medium power wide-angle views of nebulas, open star clusters,
large galaxies, and comets. Crisp views of the Moon, planets, binary
stars, and globular clusters are also routine at magnifications of
108x to 144x 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, an 8mm eyepiece will
give you a magnification of 54x (432mm/8mm = 54).
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............... 12" (305mm)
(lens shade retracted)
.............. 15" (381mm)
(lens shade extended)
... 4.65 lbs. (2.11 kg)
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