Telescope ABC’s
What do the following terms mean?
Diagonal:
A mirror that deflects the ray of light 90 degrees. With a horizontal
telescope tube, this device deflects the light upwards so that you
can comfortably observe by looking downwards into the eyepiece.
The image in a diagonal mirror appears upright, but rotated
around its vertical axis (mirror image).
Focal Length:
Everything that magnifies an object via an optic (lens) has a
certain focal length (FL). The FL is the length of the path the light
travels from the surface of the lens to its focal point. The focal
point is also referred to as the focus. In focus, the image is clear.
In the case of a telescope, the FL of the telescope tube and the
eyepieces are combined.
Lens:
The lens turns the light which falls on it around in such a way
so that the light gives a clear image in the focal point after it has
traveled a certain distance (focal length).
Eyepiece:
An eyepiece is a system made for your eye and comprised of one
or more lenses. In an eyepiece, the clear image that is generated
in the focal point of a lens is captured and magnified still more.
There is a simple formula for calculating the magnification:
Focal length of the telescope tube / Focal length of the eyepiece =
Magnification
You see: In a telescope, the magnification depends on both the
focal length of the telescope tube and the focal length of the
eyepiece.
Magnification:
The magnification corresponds to the difference between
observation with the naked eye and observation through a
magnification apparatus (e.g. a telescope). In this scheme,
observation with the eye is considered “single”, or 1x
magnification. Accordingly, if a telescope has a magnification
of 30x, then an object viewed through the telescope will appear
30 times larger than it would with the naked eye. See also
“Eyepiece.“
Troubleshooting:
Mistakes:
Help:
No picture
Remove dust protection cap
and sun-shield from the
objective opening.
Blurred picture
Adjust focus using focus ring
No focus possible
Wait for temperature to
balance out
Bad picture
Never observe through a
glass surface
Viewing object visible
Adjust finder
in the finder, but not
through the telescope
Despite using star
The star diagonal prism
diagonal prism
should be vertical in
the picture is “crooked”
the eyepiece connection
DISPOSAL
Dispose of the packaging materials properly,
according to their type (paper, cardboard, etc).
Contact your local waste disposal service or
environmental authority for information on the
proper disposal.
Please take the current legal regulations into
account when disposing of your device. You
can get more information on the proper dis-
posal from your local waste disposal service
or environmental authority.
Customer Service Questions:
1-866-252-3811
Customer Service: Call 1-866-252-3811
40mm AZ Telescope Manual
National Geographic’s net proceeds
support vital exploration, conservation,
research, and education programs.
© 2016 National Geographic Partners LLC. All rights reserved.
NATIONAL GEOGRAPHIC and Yellow Border Design are trademarks of
the National Geographic Society, used under license.
