
astro-tech

AT90EDTfrom Astronomy Technologies
Thank you for choosing this
The images from its
of your AT90EDT is little short of astonishing.
This instruction sheet will provide you with information on how to get the most out of your new refractor, 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 AT90EDT | Mounting shoe for | Focusing | ||
Lock knob for 360° | optional finder | |||
rotatable focuser | scale on | |||
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| 2” |
| focuser | |
Lock knob for |
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eyepiece |
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focuser drawtube | 1.25” |
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holder |
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Retractable dew shield | eyepiece |
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| holder |
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| Fine |
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| Mounting shoe for |
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| optional finder | Left coarse |
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| Brass compression ring |
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Dust cover | focus knob | 2” |
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| coarse | |
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| 1.25” | focus | ||
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| 2” eyepiece |
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| lock knob |
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| 1.25” eyepiece | 1.25” |
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| lock knob |
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| eyepiece |
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| lock knob |
Aperture | 90mm (3.54”) | Finder | mounting shoe provided for optional | |||
Focal Length | 600mm | |||||
Focal Ratio | f/6.7 | Lens Shade |
| retractable | ||
Objective Type | collimatable | Lens Shade Outer Diameter | ....................... | 130mm | ||
| using Ohara | Objective Lens Cover | ||||
Optical Coatings | fully multicoated | Tube Diameter | 114mm o. d. | |||
Resolving Power (Dawes’ Limit) | 1.29 arc seconds | Tube Length (lens shade retracted) | 18.9” (480mm) | |||
Visual Limiting Magnitude | 12.3 maximum | Tube Length (lens shade extended) .... | 21.75” (552mm) | |||
Light Grasp (versus the eye) | 165x | Optical Tube Weight | 11.45 lbs. (5.2 kg) | |||
Field Stops | three | Case | ||||
Focuser |
| lockable hard case, with carrying handle | ||||
| with 11:1 reduction ratio fine focus; | Case Dimensions | 28” x 9” x 9” | |||
2” and 1.25” compression ring eyepiece holders; | Lowest Usable Power | 15x (40mm eyepiece) | ||||
360° rotating camera angle/observing angle adjuster | Highest Terrestrial Power | 85x (7mm eyepiece) | ||||
Focuser Travel | 4.7” (120mm) | Highest Practical Power | 150x (4mm eyepiece) | |||
with millimeter scale on drawtube for repeatable focus | Theoretical Maximum | 200x (3mm eyepiece) |