Astro-Tech AT-80 User Manual

astro-tech A T-80
Thank you for choosing this Astro-Tech AT-80 high-quality
short tube achromatic refractor.
Noted refractor designer Thomas M. Back called it a "high
quality achromat." He said of the AT-80's optics, "The first
thing I noticed was the excellent multicoatings. The
reflectivity was very low, noticeably better than any other
standard achromat I've seen. On my optical test bench, the
wavefront was well above average. No coma, astigmatism,
zones, and the spherical correction was corrected well beyond
the diffraction limit. Contrast was also very high, making
PARTS OF THE AT-80
1/4"-20 thread
tripod mounting holes
L-bracket mounting shoe
Dust cover
on a white-finish AT-80, as it
can become difficult to remove. A light touch is all that is
needed to keep the dust cover in place.
Aperture ................................................... 80mm (3.1")
Focal Length .................................................... 480mm
Focal Ratio ............................................................... f/6
Objective Type ................crown and flint glass doublet
Optical Coatings ................................ fully multicoated
Resolving Power (Dawes' Limit) ...... 1.45 arc seconds
Visual Limiting Magnitude .................. 12.0 maximum
Light Grasp (versus the eye) ............................... 131x
Lens Shade ................................................. retractable
Field Stops .... 10 glare-reducing baffles in optical tube
Focuser ............................... dual-speed Crayford-type
with 11:1 reduction ratio fine focus speed;
360° rotating camera angle/observing angle adjuster;
and 2" compression ring eyepiece holder
Focuser Travel ....................................... 3.15" (80mm)
with millimeter scale on drawtube for repeatable focus
Retractable dew shield
Lock screw
for focuser drawtube
Brass compression ring
Dust cover note: The
dust cover is a snug fit on
the white tube AT-80, due
to the textured paint finish.
Do not press the dust cover
onto the dew shield too firmly
Astro-Tech AT-80 Achromatic Refractor Specifications
from Astronomy Technologies
this lens excellent for not only wide field views, but lunar
and planetary work." That's high praise indeed from someone
renowned for designing apochromatic refractors costing as
much as $92,990.
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.
Lock knob for 360°
rotatable focuser
Mounting point
for optional finder
Coarse focus knob
2" compression
ring eyepiece holder
1.25" eyepiece
lock knob
Supplied 1.25" Adapter ........... compression ring type
Objective Lens Cover ............................. slip-on metal
Tripod Mount ............................. removable L-bracket,
Tube Diameter ............................................ 90mm o. d.
Tube Weight ........................................ 5.5 lbs. (2.5 kg)
Tube Length (lens shade retracted) ... 15.25" (385mm)
Tube Length (lens shade extended) ... 17.75" (450mm)
Optical Tube Weight ............................ 5.5 lbs. (2.4 kg)
Case ................... zippered nylon soft case, foam-fitted,
Case Dimensions ................................... 18" x 11" x 6"
Lowest Usable Power ........ 12x (with 40mm eyepiece)
Highest Terrestrial Power ... 80x (with 6mm eyepiece)
Highest Practical Power .... 120x (with 4mm eyepiece)
Theoretical Maximum ........ 160x (with 3mm eyepiece)
1.25" eyepiece
1.25"
eyepiece
adapter
with 1/4"-20 thread mounting holes
with carrying handles and shoulder strap
Focusing
scale on
focuser
drawtube
Fine
focus
knob
2" eyepiece
lock knob
lock knob