Pentax 10 - Manual (Page 17)

17
Viewing
Begin with lower power. Begin with lower power. Begin with lower power. Begin with lower power. Begin with lower power.
If you are not an experienced observer, use eyepieces in the 20-40 mm
focal length range to make finding objects easier. The wider field is
more likely to contain what you are looking for, and moving the scope
while viewing is much less critical.
Learn “which way is up”. Learn “which way is up”. Learn “which way is up”. Learn “which way is up”. Learn “which way is up”.
Newtonian optical systems produce an inverted and reversed image, so
when you move the scope, the image moves the opposite way. Think of
it as pushing the object, not the scope, and you will quickly adjust to
the reverse motions.
Learn to follow as the earth turns. Learn to follow as the earth turns. Learn to follow as the earth turns. Learn to follow as the earth turns. Learn to follow as the earth turns.
Objects will follow circular paths east to west. Remember that your
scope will need to move in that same direction to keep them in view.
Learn to move the scope along both axes as needed so that when you
release it, the object will slowly drift through the center of the field as
the earth rotates.
Areas of the Sky Areas of the Sky Areas of the Sky Areas of the Sky Areas of the Sky
Images of objects nearer the horizon will be adversely affected by the
increased travel of the light through the atmosphere. Objects are best
when viewed higher in the sky.
A special situation exists with the sky area directly overhead. This is
often referred to by users of altazimuth telescopes as “Dobson’s Hole”.
Movement of a telescope about it’s vertical (azimuth) axis is more
difficult here than other parts of the sky because the lever arm used to
turn it in azimuth is almost zero. Learn to twist, rather than push the
scope in this part of the sky, and you will reduce the difficulty. A firm
grasp in the opening of the secondary cage will help.
Recommended References
Nightwatch by Terrence Dickinson (Camden House; Camden East,
Ontario; revised edition, 1993)
The Sky: A User’s Guide by David H. Levy (Cambridge; New York;
1991)
The Universe From Your Backyard by David J. Eicher (Cambridge;
New York; 1988)
The Backyard Astronomer’s Guide by Terrence Dickinson & Alan
Dyer (Camden House; Camden East, Ontario; 1991)