6
solar system observing
Though optimized for wide-field astronomical viewing, you can
use higher-power eyepieces with the Express 80mm to enjoy
exciting views of the Moon, Sun, and planets.
A. The Moon
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 fascination. The best time to observe surface fea-
tures on 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.
Use an optional Moon filter to dim the Moon when it is very
bright. It simply threads onto the bottom of the eyepiece (you
must first remove the eyepiece to attach the filter). You’ll find
the Moon filter improves viewing comfort, and helps bring out
the subtle features in the lunar surface.
B. The Sun
You can change your telescope into a daytime Sun viewer
by installing an optional full-aperture solar filter over the front
opening of the Express 80mm. The primary attraction is sun-
spots, which change shape, appearance, and location daily.
Sunspots are directly related to magnetic activity in the Sun.
Many observers like to make drawings of sunspots to monitor
how the Sun is changing from day to day.
Important Note: Do not look at the Sun with any optical instru-
ment without a professionally made solar filter, or permanent
eye damage could result.
C. The Planets
The planets don’t stay put like stars do (planets don’t have
fixed R.A. and Dec. coordinates), so you will have to refer to
Sky Calendar at our website, www.OrionTelescopes.com, to
a desktop planetarium software package, to charts published
monthly in Astronomy, Sky & Telescope, or other astronomy ref-
erences to locate them. First find the planet using a low-power
eyepiece. Then raise the magnification as high as atmospher-
ic seeing will allow. Venus and Mercury will show distinct and
changing phases when viewed through the Express 80mm.
(Caution: do not attempt to view any planet when it is near the
Sun in the sky.) Mars’ apparent size varies greatly depending
on its orbital position relative to Earth; during close approach-
es you will be able to observe its polar ice caps and dark rocky
patches on its surface. Jupiter will display its distinctive cloud
bands and the constantly changing positions of its four largest
moons. Saturn’s system of rings and largest moon Titan will be
clearly visible. The planets Uranus and Neptune are too distant
to show significant detail even in very large telescopes, but
you will be able to pick them out from the background stars by
their amazing blue-green color.
using Filters
A wide variety of filters can greatly enhance your views through
the Express 80mm. For galaxies, star clusters, star fields and
dark nebulae, a broad-band light pollution reduction filter can
be a great benefit in skies brightened by city lights. Emission
nebulae will often be much more visible using narrowband neb-
ula filters, even in dark skies. A range of color filters will bring
out different subtle details in the planets. Moon filters provide
a more comfortable view of the dazzlingly bright Moon in its
fuller phases, and can also be useful when viewing Venus.
These filters are designed to screw into the threads at the bot-
tom of your eyepieces, and come in both 1.25" and 2" sizes.
The 1.25" eyepiece adapter included with the Express 80mm
is threaded to accept 2" filters. This is a great convenience
when using the 1.25" eyepiece adapter in a 2” diagonal, as you
no longer have to detach and re-attach the filter every time you
change 1.25" eyepieces.
Photography with the
Express 80mm
With an optional camera adapter, the Express 80mm becomes
a 480mm f/6 telephoto lens for a single-lens reflex camera with
a removable lens. This is known as the prime focus method of
photography through your telescope. A 2" camera adapter will
provide the most even field illumination across your camera’s
field of view. The camera adapter is secured directly to the
focuser drawtube in place of the diagonal. You will also need
a T-ring for your particular camera model. The T-ring attaches
to your particular camera model and threads onto the camera
adapter (Figure 4).
Many popular cameras do not have removable lenses. You
can get excellent pictures through your telescope with these
cameras if you use the afocal method. This method essentially
replaces your eye with the camera and requires the use of an
adapter, such as the Orion SteadyPix, to hold the camera up
to the eyepiece.
Whichever method of photography you use, be sure to secure
your camera and camera adapter to the telescope by tighten-
ing the thumbscrew on the focuser drawtube, or your camera
could fall to the ground! Use the telescope’s focuser to focus
the image. Tighten the focus lock thumbscrew on the under-
side of the telescope’s focuser to make sure the camera does
not slip out of focus. You will want to consider using a remote
shutter release instead of the manual shutter release on the
camera; touching the camera can vibrate the system and blur
the resulting photographic image. Also, be sure to use a solid
tripod.
2" Camera adapter
T-ring
Figure 4.
To connect a 35mm SLR camera to the Express 80mm,
you’ll need an optional camera adapter and T-ring.