Acer Victoria wrote:
> Grind mirrors? What's that?
> Oh, the prof/dept. chair mentioned he also had some Vivitar thingy for the
> scope (when I mentioned Tmount). I'll ask what that is too.
Unless the scopes are catadioptic (I doubt it with those small f
numbers) the scopes you are borrowing are probably Newtonian reflector
telescopes, I suspect on a "Dobsonian" altazamuth mount. These can be
wonderful telescopes to sweep the skies. With those large mirrors and a
low power eyepiece you'll even be able to see some deep sky objects such
as nebulae and nearby galaxies if you are in a dark place. Higher power
will give beautiful views of the planets (I think Jupiter and Saturn are
visible now). The mount, however, is not likely to have a clock drive to
track the stars. They should gather enough light to get good pictures
of the moon as the exposures will be short enough to arrest the apparent
motion of the moon. They may have a "moon" filter to enhance contrast.
As far as grinding a mirror, the main mirrors are made by carefully
grinding a parabolic shape into a blank of pyrex glass using
successively finer grades of carborundum and finally rouge then coating
the mirror with aluminum to make it reflective. It's amazing how good a
curve can be produced without any high priced equipment. Good amatures
will typically produce a curve accurate to within 1/4 wavelength of
light! Amature telescope making used to be a big deal with many people
still making their own instruments.
Jerry Liles
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