Astro-imaging Page Astrophotography is a combination
of art and science. Because the Earth is rotating during the exposure,
the telescope must be slewing at the same rate, but in the opposite direction
to keep the object being photographed in the center of the frame. This
is done by a drive motor attached to the telescope's mount which must be
exactly parrallel with the Earth's axis; a technique known as Polar
Alignment. Still, fine adjustments must be made constantly by the astrophotographer
to compensate for mechanical errors in the drive, changes in frequency
of the line voltage to the drive motor, and image shifting caused by the
shimmering effects of the atmosphere called Seeing.
This technique is called Guiding
and requires that the astrophotographer keep constant vigil at the guiding
eyepiece of the telescope for the duration of the exposure.
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Wes Schwarz Astro Images |