Orion NEWTONIAN ASTROGRAPH 9527 - Manual (Page 5)

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is centered on the crosshairs of the finder scope and in the
telescope’s eyepiece, the finder scope is aligned and ready to
be used for locating objects.
The finder scope alignment should be checked before every
imaging or observing session. This can easily be done at night,
before viewing through the telescope. Choose any bright star
or planet, center the object in the telescope eyepiece, and
then adjust the bracket’s alignment screws until the star or
planet is also centered on the finder’s crosshairs.
Focusing the Finder Scope
If the image in the finder scope appears out of focus, you will
need to refocus the finder scope for your vision. First, loosen
the lock ring located behind the objective lens cell on the body
of the finder scope
(Figure 3). Back the lock ring off by a few
turns. Then refocus the finder scope on a distant object by
rotating the objective lens cell clockwise or counterclockwise.
Once the image appears sharp, retighten the lock ring behind
the objective lens cell. The finder scope’s focus should not
need to be adjusted again.
Operating the 8" f/4.0
Newtonian Astrograph
Your 8" f/4.0 Newtonian Astrograph is designed primarily for
astro-imaging, but it makes a fine visual instrument as well.
For visual use, we recommend using high-quality eyepieces
to take full advantage of the instrument’s exceptional optical
quality. For imaging applications, the telescope is optimized
for use with an APS-C size sensor, found in such cameras as
the Orion StarShoot
™ Pro, Orion Parsec ™ , and many DSLRs.
Cooling the Telescope
All optical instruments need time to reach “thermal equilibri-
um.” The bigger the instrument and the larger the temperature
change, the more time is needed. Allow at least 30 minutes
for your telescope to cool to the temperature outdoors. In very
cold climates (below freezing), it is essential to store the tele-
scope as cold as possible. If it has to adjust to more than a
40°F temperature change, allow at least one hour. You can
use the telescope while it’s cooling down, just note that you
may see “tube currents,” which interfere with the telescope’s
ability to resolve a sharp image. Tube currents are essential-
ly heat waves exiting both the optical components (such as
the primary mirror) and the telescope itself. The effect seen
through the eyepiece is much like looking above a hot surface
or fire.
Mirror Cooling Fan
The 8" f/4.0 Newtonian Astrograph comes with a cooling fan
installed on the rear of the primary mirror cell
(Figure 5).
Using the fan reduces the amount of time required for the pri-
mary mirror to reach thermal equilibrium with the ambient air.
The fan is powered by 12-volts DC. The included battery hold-
er holds eight AA alkaline batteries (not included). Plug the
cable from the battery holder into the fan’s power jack located
on the rear cell. Alternatively, the fan can be powered by a
12-volt DC field battery, such as the Orion Dynamo Pro.
You can run the fan prior to starting your imaging or observing
session, then turn it off, or keep it running during the ses-
sion, as there should be no noticeable vibration. However, it
is probably not necessary to run the fan continuously for long
periods of time, unless the temperature is changing continu-
ously and rapidly.
Figure 5. Rear of telescope
showing the installed cooling fan
and six collimation adjustment
knobs (three black collimation
knobs and three white lock knobs).
Black collimation
knob (x3)
White lock
knob (x3)
Power jack
Cooling fan
Back of
primary mirror