8 Inch Telescope Mirror Blank for grinding a Newtonian Reflector Grind your own For Sale
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8 Inch Telescope Mirror Blank for grinding a Newtonian Reflector Grind your own:
$35
8 inch plate glass mirror blank, 3/4 inch thick. Tested to be free of internal strain. Heard that plate glass blanks are inferior to Pyrex for telescope mirrors? Not true. When properly made and supported, plate glass blanks take
on and maintain every bit as accurate a parabola as borosilicate blanks
- but don't take my word for it. Sky and Telescope writes "the idea
that Pyrex telescope mirrors are better than those made from plate
glass" is "demonstrably incorrect and may have caused many a telescope
owner unnecessary effort, expense, or angst" ... and from the same
article... "our tests of six 8-inch Dobsonians (S&T: January 2000,
page 60) showed no correlation between glass types and optical
quality." Read the full article here:
Blanks may have minor surface scratches or
edge imperfections which will have no effect whatsoever on the grinding
of your mirror blank, or the final quality of your mirror
