Celestron Firstscope 80 AZ Instruction Manual page 13

Your Celestron can be used for both terrestrial and astronomical photography. You
can use your telescope as a high power telephoto lens with the use of the optional T-
Adapter. The Firstscope can also be used as a stable mount by attaching a camera to
the photo adapter screw on the top of the tube ring. Celestron telescopes have fixed
apertures and, as a result, fixed f/ratios. To properly expose your subjects photo¬
graphically you need to set your shutter speed accordingly. Most 35mm cameras
offer through-the-lens metering which will let you know if your picture will be
under or over exposed. This is more of a consideration when doing terrestrial
photography where exposure times are measured in hundredths of a second. In
astrophotography, the exposures are much longer requiring that you use the "B"
setting on your camera. The actual exposure time is determined by how long you
keep the shutter open.
To reduce vibration when tripping the shutter, use a cable release. Releasing the
shutter manually can cause vibration, something that can produce unsharp photos.
A cable release will keep your hands clear of the camera and telescope, thus elimi¬
nating the possibility of introducing vibration. Mechanical shutter releases can be
used, though air type releases are best.
Photographing the
Moon
After looking at the night sky for a while you may want to try photographing it. If
you do, start with a nice, bright object like the Moon.
Load your camera with film that has a moderate-to-fast speed (i.e., ISO rating).
Faster films are more desir¬
able when the Moon is a
crescent. When the Moon is
full, and at its brightest,
slower films are more
desirable. If photographing
during the full phase, use a
yellow filter to reduce the
light intensity and to increase
contrast. To attach your
camera to the telescope you
will need the Celestron T-
Adapter (#93634-A) and the
T-Ring for your specific
camera.
Consult the Celestron
accessory catalog for a list of recommended exposure times. These exposure times
should be used as a starting point. Always make exposures that are longer and
shorter than the recommended time. Also, try bracketing your exposures. Take a
few photos at each shutter speed. This will ensure that you will get a good photo.
Keep accurate records of your exposures. This information is useful if you want to
repeat your results or submit them for possible publication in astronomical maga¬
zines!
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