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Terrestrial Viewing
The 45° diagonal provided with the ShortTube 80mm provides a
correctly oriented image. If, instead of the 45° diagonal, you use an
optional 90° "star diagonal," which is preferred for astronomical use,
the view will be right-side up but backwards.
It's best to start observing with the lower-power (25mm) eyepiece,
because it offers the wider field of view. With the eyepiece inserted
and secured in the 45° diagonal, simply point the telescope at the sub-
ject you want to observe and center it on crosshairs of the finder scope
(which you've previously aligned with the main telescope, as explained
in the preceding section). Then look into the eyepiece and the subject
should be in the center of the field of view. If the view is blurry, adjust
the focus with the focus knob until the image appears sharp.
If you want higher magnification, switch to the 10mm eyepiece and
readjust the focus as necessary. Remember, increasing the magnifi-
cation decreases the field of view and the image brightness.
astronomical Viewing
When selecting a location for nighttime stargazing, make it as far
away from city lights as possible. Light-polluted skies greatly reduce
what can be seen with a telescope. A grass or dirt surface is prefer-
able to asphalt, because asphalt radiates more heat, which disturbs
the air and compromises your view.
To find celestial objects with your telescope, you first need to become
reasonably familiar with the night sky. Unless you know how to rec-
ognize the constellation Orion, for instance, you won't have much
luck locating the Orion Nebula. A simple planisphere, or star wheel,
can be a valuable tool for learning the constellations and seeing
which ones are visible in the sky on a given night.
A good star chart or atlas can come in very handy for helping find
objects among the dizzying multitude of stars overhead. Except for
the Moon and the brighter planets, it's pretty time-consuming and
frustrating to hunt for objects randomly, without knowing where to
look. You should have specific targets in mind before you begin
looking through the eyepiece.
The Moon, with its rocky, cratered surface, is one of the easiest and
most interesting subjects to observe with your telescope. The myriad
craters, rilles, and jagged mountain formations offer endless fasci-
nation. The best time to observe the Moon is during a partial phase,
that is, when the Moon is not full. During partial phases shadows
cast by crater walls and mountain peaks along the border between
the dark and light portions of the lunar disk highlight the surface
relief. A full Moon is too bright and devoid of surface shadows to
yield a pleasing view.
Under dark skies, you can also observe a number of brighter deep-
sky objects, including gaseous nebulas, open and globular star
clusters, and different types of galaxies. Most deep-sky objects are
very faint, so it is important that you find an observing site well away
from light pollution. Take plenty of time to let your eyes adjust to
the darkness. Don't expect these subjects to appear like the photo-
graphs you see in books and magazines; most will look like dim gray
smudges. (Our eyes are not sensitive enough to see color in deep-
sky objects except in few of the brightest ones.) But as you become
more experienced and your observing skills get sharper, you will be
able to see more and more detail.
For astronomical observing, you may wish to replace the 45°
diagonal with an optional 90° star diagonal, which provides a more
comfortable viewing angle for observing objects overhead, and also
yields slightly better image resolution.
Photography with the ShortTube 80mm
With an optional camera adapter, the ShortTube 80mm becomes a
400mm f/5 telephoto lens for a single-lens reflex (SLR) camera. For
long-distance terrestrial or astronomical photography, you need only
a T-ring for your particular camera model. The T-ring screws onto
the threads on the ShortTube's focuser drawtube, coupling the cam-
era body to the telescope. For closer-range terrestrial photography,
you need both a T-ring for your camera and a T-Adapter (Orion item
#5264), which provides the extra focus travel needed.
Care & Maintenance
Give your telescope reasonable care and it will last a lifetime. Store
it indoors or in a dry garage. Do not leave the telescope outside
except when using it. The optical tube is aluminum and has a
smooth painted surface that should resist scratches and smudges.
If a scratch does appear on the tube, it will not harm the telescope.
If you wish, you can apply some white auto touch-up paint to the
scratch. Smudges on the tube can be wiped off with standard
household cleaners such as Windex or Formula 409.
Any quality optical lens cleaning tissue and optical lens cleaning fluid
specifically designed for multi-coated optics can be used to clean
the telescope's objective lens as well as the lenses of the eyepiec-
es and finder scope. Never use regular glass cleaner or cleaning
fluid designed for eyeglasses. Before cleaning with fluid and tissue,
however, blow any loose particles off the lens with a blower bulb
or compressed air, or lightly brush the lens with a soft camel-hair
brush. Apply some cleaning fluid to a tissue, never directly on the
optics. Wipe the lens gently in a circular motion, then remove any
excess fluid with a fresh lens tissue. Oily fingerprints and smudges
may be removed using this method. Use caution; rubbing too hard
may scratch the lens! On larger lenses, clean only a small area at a
time, using a fresh lens tissue on each area. Never reuse tissues.
Also, do not take eyepieces apart to clean them.
Specifications
Optical tube length: 15"
Objective lens: 80mm glass achromat
Focal length: 400mm
Focal ratio: f/5
Finder scope: 6x magnification, 30mm aperture, correctly oriented
image
Mount type: 1/4"-20 threaded receptacle
Eyepieces: 25mm (16x) and 10mm (40x) Kellner, 1.25"
Weight of optical tube assembly: 3 lbs., 7 oz.
One-Year Limited Warranty
Orion ShortTube 80mm
materials or workmanship for a period of one year from
the date of purchase. This warranty is for the benefit of the
original retail purchaser only. During this warranty period
Orion Telescopes & Binoculars will repair or replace, at
Orion's option, any warranted instrument that proves
to be defective, provided it is returned postage paid to:
Orion Warranty Repair, 89 Hangar Way, Watsonville, CA
95076. Proof of purchase (such as a copy of the original
invoice) is required.
This warranty does not apply if, in Orion's judgment, the
instrument has been abused, mishandled, or modified,
nor does it apply to normal wear and tear. This warranty
gives you specific legal rights, and you may also have
other rights, which vary from state to state. For further
warranty service information, contact: Customer Service
Department, Orion Telescopes & Binoculars, P. O. Box
1815, Santa Cruz, CA 95061; (800) 676-1343.
is warranted against defects in
™
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