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10
Image orientation as seen with the
unaided eye & using erecting devices
on refractors & Newtonians
Inverted image, normal with
Newtonians & as viewed with
eyepiece directly in a refractor
Reversed from left to right, as
viewed using a Star Diagonal on a
refractor
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The image orientation changes depending on how the eyepiece is inserted into the telescope. When using a star
diagonal with refractors, the image is right-side-up, but reversed from left-to-right (i.e., mirror image). If inserting
the eyepiece directly into the focuser of a refractor (i.e., without the diagonal), the image is upside-down and
reversed from left-to-right (i.e., inverted). However, when using the AstroMaster refractor and the standard erect
image diagonal, the images is correctly oriented in every aspect.
Newtonian reflectors produce a right-side-up image but the image will appear rotated based on the location of the
eyepiece holder in relation to the ground. However, by using the erect image eyepiece supplied with the
AstroMaster Newtonians, the image is correctly oriented.
Figure 3-3
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To focus your refractor or Newtonian telescope, simply turn the focus knob located directly below the eyepiece
holder (see Figures 1-1 and 1-2). Turning the knob clockwise allows you to focus on an object that is farther than
the one you are currently observing. Turning the knob counterclockwise from you allows you to focus on an object
closer than the one you are currently observing.
Note: If you wear corrective lenses (specifically glasses), you may want to remove them when observing with an
eyepiece attached to the telescope. However, when using a camera you should always wear corrective lenses to
ensure the sharpest possible focus. If you have astigmatism, corrective lenses must be worn at all times.
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The Star Pointer is the quickest and easiest way to point your telescope exactly at a desired object in the sky. It's
like having a laser pointer that you can shine directly onto the night sky. The Star Pointer is a zero
magnification pointing tool that uses a coated glass window to superimpose the image of a small red dot onto
the night sky. While keeping both eyes open when looking through the Star Pointer, simply move your
telescope until the red dot, seen through the Star Pointer, merges with the object as seen with your unaided eye.
The red dot is produced by a light-emitting diode (LED); it is not a laser beam and will not damage the glass
window or your eye. The star pointer is powered by a long life 3-volt lithium battery (#CR1620) see Figure 3-4.
Like all finderscopes, the Star Pointer must be properly aligned with the main telescope before it can be used.
The alignment procedure is best done at night since the LED dot will be difficult to see during the day.