Thank you for choosing this
Astro-Tech AT90EDT
high-performance apochromatic ED triplet refractor.
The images from its fully-collimatable 600mm f/6.7
ED (Extra-low Dispersion) air-spaced triplet optics are
virtually color-free, even at high magnifications, thanks
to its use of advanced Ohara FPL-53 ED glass. At its
price, we believe you’ll find that the optical performance
Aperture
............................................ 90mm (3.54”)
Focal Length
...............................................600mm
Focal Ratio
...................................................... f/6.7
Objective Type
........... collimatable air-spaced triplet
using Ohara FPL-53 ED glass
Optical Coatings
........................... fully multicoated
Resolving Power
(Dawes’ Limit)
....... 1.29 arc seconds
Visual Limiting Magnitude
.............. 12.3 maximum
Light Grasp
(versus the eye)
.............................. 165x
Field Stops
.......................... three knife-edge baffles
Focuser
.......................... dual-speed rack and pinion
with 11:1 reduction ratio fine focus;
2” and 1.25” compression ring eyepiece holders;
360° rotating camera angle/observing angle adjuster
Focuser Travel
.................................. 4.7” (120mm)
with millimeter scale on drawtube for repeatable focus
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.
Astro-Tech AT 90 EDT Apochromatic ED Triplet Refractor Specifications
Finder
................mounting shoe provided for optional
Astro-Tech multiple reticle finder or similar finder
Lens Shade
............................................ retractable
Lens Shade Outer Diameter
.......................130mm
Objective Lens Cover
.........................slip-on metal
Tube Diameter
.................................... 114mm o. d.
Tube Length
(lens shade retracted)
...... 18.9” (480mm)
Tube Length
(lens shade extended)
....21.75” (552mm)
Optical Tube Weight
...................11.45 lbs. (5.2 kg)
Case
............................. aluminum-frame foam-fitted
lockable hard case, with carrying handle
Case Dimensions
................................ 28” x 9” x 9”
Lowest Usable Power
............ 15x (40mm eyepiece)
Highest Terrestrial Power
.......85x (7mm eyepiece)
Highest Practical Power
........ 150x (4mm eyepiece)
Theoretical Maximum
........... 200x (3mm eyepiece)
Retractable dew shield
Lock knob for
focuser drawtube
Lock knob for 360°
rotatable focuser
PARTS OF THE AT 90EDT
Left coarse
focus knob
Fine
focus
knob
Focusing
scale on
focuser
drawtube
1.25”
eyepiece
holder
1.25” eyepiece
lock knob
Dust cover
1.25” eyepiece
lock knob
Brass compression ring
Right
coarse
focus
knob
1.25”
eyepiece
holder
Mounting shoe for
optional finder
2” eyepiece
lock knob
2”
eyepiece
holder
2”
eyepiece
holder
1.25”
eyepiece
holder
astro-tech
AT 90 EDT
from Astronomy Technologies
Mounting shoe for
optional finder
