16 I ENGLISH
CELESTIAL OBSERVING TIPS
This section covers visual observing hints for both solar system and deep-sky objects as well as general observing
conditions which will affect your ability to observe.
MAGNIFICATION
You can change the magnification of your telescope by simply changing eyepieces. Both telescopes and eyepieces have focal lengths
that are measured in millimeters. To calculate the magnification of a given telescope and eyepiece combination, take the focal length of the
telescope and divide it by the focal length of the eyepiece. The resulting number is the magnification factor.
For example, the AstroMaster 90EQ has a focal length of 1000 mm. Using the 20 mm eyepiece:
1000 mm
=
____________
= 50x
20 mm
Focal length of Telescope
Magnification =
_________________________
Focal length of Eyepiece
With the Moon visible in the sky, set up your telescope
with the 20mm eyepiece installed.
The best and easiest target for you to try to view first is the Moon. Try observing the Moon at different points in its phase cycle. The best time to view the Moon is from two days
after a New Moon up to a few days before a Full Moon. During this period, you will be able to see the most detail in the craters and lunar mountain ranges.
Move the telescope so that it is roughly pointing
toward the Moon.
Look through the finderscope and locate the red dot.
Continue moving the telescope until the red dot
appears over the Moon.
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YOUR FIRST NIGHT OUT - THE MOON
Look through the telescope’s 20mm eyepiece. Gently turn
the focus knobs to adjust the sharpness of the image.
You can view many other celestial objects, such as planets,
star clusters and nebulae using this same technique if you
know where to find them in the night sky.
To get a closer view of the Moon, loosen the thumbscrews on
the focuser and remove the 20mm eyepiece. Replace it with
your 10mm eyepiece and tighten the thumbscrews to secure
it in place. The 10mm eyepiece will give you significantly more
magnification, making the Moon appear much larger.
NOTE: You may need to adjust the focus knobs when you
change eyepieces to make sure you are getting the
sharpest image possible.
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CONGRATULATIONS!
YOU HAVE NOW OBSERVED YOUR
FIRST CELESTIAL OBJECT!
44
55
10mm
20mm
20mm Eyepiece
Focus Knobs
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