In a message dated 9/27/99 2:02:58 PM Eastern Daylight Time,
siddim01@xxxxxxxxxxxxxxx writes:
> Yes, that was my question...although I still don't get it.
OK, let's try it this way:
The earth rotates/stars move at 15 degrees per hour. With a 50mm lens, your
angle of view (diagonally) is about 47 degrees. So for a star to move from
one corner of the field to the other (about 43mmm at the film plane) takes a
little over 3 hrs.
For a 200mm lens which has an approximately 12 degree field (I think), the
star would move the 43mm from one corner of the field to the other in under
an hour (about 48 mins).
Does this make any sense?
Paul Schings
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