astro-tech AT66ED
from Astronomy Technologies
Thank you for choosing this Astro-Tech AT66ED high-
quality compact apochromatic refractor.
you’ll find that the optical performance of your AT66ED is
little short of astonishing.
While some observers might doubt that apochromatic
performance can be had in a 66mm scope that costs as little
as the AT66ED, we can say only that seeing is believing.
The images from its 400mm f/6 ED (Extra-low Dispersion
glass element) air-spaced doublet optics are virtually color-
free, even at high magnifications. At its low price, we believe
This instruction manual 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.
Locking collar for 360°
Mounting point for
optional finder
PARTS OF THE AT66ED
rotatable focuser
Retractable dew shield
Focusing
Thread-on
scale on
1.25”
focuser
eyepiece
drawtube
adapter
Astro -Tech
1/4”-20 thread
tripod mounting holes
in base of bracket
Lock knob
for focuser drawtube
underneath body
Fine
focus
knob
Left coarse
focus knob
Combined equatorial mount
dovetail and L-bracket
Right
Dust cover
coarse
focus
knob
Dust
cap
tripod mounting shoe
Brass compression ring
1.25” eyepiece
lock knob
1.25” eyepiece
lock knob
Thread-on 1.25”
eyepiece
adapter
Astro-Tech AT66ED Apochromatic Refractor Specifications
Aperture ................................................... 66mm (2.6”) Objective Lens Cover............................. slip-on metal
Focal Length ....................................................400mm Tripod Mount ... removable combination L-bracket and
Focal Ratio ...............................................................f/6
ObjectiveType .... air-spaced doublet with ED element
Optical Coatings................................ fully multicoated
dovetail with 1/4”-20 thread mounting holes for photo
tripod use as well as direct mounting on Celestron,
Meade, and Vixen German equatorial mounts
Resolving Power (Dawes’ Limit) ...... 1.75 arc seconds Tube Diameter............................................ 75mm o. d.
Visual Limiting Magnitude.................. 11.6 maximum Tube Length (lens shade retracted) ..... 11.5” (292mm)
Light Grasp (versus the eye) ................................. 89x Tube Length (lens shade extended)..... 14.4” (366mm)
Field Stops .... 10 glare-reducing baffles in optical tube OpticalTube Weight............................ 3.9 lbs. (1.8 kg)
Focuser ............................... dual-speed Crayford-type Case.................................. aluminum-frame foam-fitted
with 11:1 reduction ratio fine focus;
lockable hard case, with carrying handle
360° rotating camera angle/observing angle adjuster; Case Dimensions .............................15” x 9.5” x 6.25”
and thread-on 1.25” compression ring eyepiece holder Lowest Usable Power........ 10x (with 40mm eyepiece)
FocuserTravel ......................................... 2.4” (60mm) HighestTerrestrial Power ... 67x (with 6mm eyepiece)
with millimeter scale on drawtube for repeatable focus Highest Practical Power.... 100x (with 4mm eyepiece)
Lens Shade .................................................retractable Theoretical Maximum........ 133x (with 3mm eyepiece)
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