
astro-tech AT66ED

from Astronomy Technologies
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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
you’ll find that the optical performance of your AT66ED is little short of astonishing.
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.
PARTS OF THE AT66ED | Locking collar for 360° | Mounting point for |
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| rotatable focuser | optional finder |
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Retractable dew shield |
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| Focusing | |
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| scale on | |
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| 1.25” | |
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| focuser | |
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| eyepiece | |
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| drawtube | |
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| adapter | |
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Lock knob |
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| Fine | ||
tripod mounting holes | for focuser drawtube | Left coarse | |||
focus | |||||
in base of bracket | underneath body | ||||
focus knob |
| knob | |||
Combined equatorial mount |
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| Right | |||
Dust cover | dovetail and |
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| Dust | coarse | |||
| tripod mounting shoe | ||||
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| cap | focus | ||
| Brass compression ring |
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| knob | |
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| 1.25” eyepiece |
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| 1.25” eyepiece | |
| lock knob | ||||
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lock knob | eyepiece |
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| adapter |
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Astro-Tech AT66ED Apochromatic Refractor Specifications
Aperture | 66mm (2.6”) |
Focal Length | 400mm |
Focal Ratio | f/6 |
Objective Type ....
Optical Coatings | fully multicoated |
Resolving Power (Dawes’ Limit) | 1.75 arc seconds |
Visual Limiting Magnitude | 11.6 maximum |
Light Grasp (versus the eye) | 89x |
Field Stops .... 10
Focuser | ............................... |
| with 11:1 reduction ratio fine focus; |
360° rotating camera angle/observing angle adjuster; and
Focuser Travel | 2.4” (60mm) |
with millimeter scale on drawtube for repeatable focus
Lens Shade | retractable |
Objective Lens Cover .............................
Tripod Mount ... removable combination
Tube Diameter |
| 75mm o. d. | |
Tube Length (lens shade retracted) | ..... 11.5” (292mm) | ||
Tube Length (lens shade extended) | ..... 14.4” (366mm) | ||
Optical Tube Weight |
| 3.9 lbs. (1.8 kg) | |
Case | |||
lockable hard case, with carrying handle | |||
Case Dimensions |
| 15” x 9.5” x 6.25” | |
Lowest Usable Power | 10x (with 40mm eyepiece) | ||
Highest Terrestrial Power | ... 67x | (with 6mm eyepiece) | |
Highest Practical Power .... | 100x | (with 4mm eyepiece) | |
Theoretical Maximum | 133x | (with 3mm eyepiece) |