Providing telescope mirror blanks in 4, 6, 8, 10, and 12 inch diameters. Our mirror blanks are made from 3/4 inch annealed plate glass, individually tested for internal strain. We also provide 5, 7, 9, 11, 13, and 14 inch telescope mirror blanks upon request.
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 our 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: Plate vs. Pyrex .
Benefits of thin mirror blanks
There are advantages to using thin plate glass mirror blanks for grinding your telescope mirror:
* Thin mirror blanks are less expensive, allowing more people to afford the hobby of grinding their own telescope mirror.
* Choosing a thin mirror blank gets you more aperture for your dollar.
* Telescope mirrors made from thin mirror blanks take less time to thermally equalize with the surrounding air when moving your telescope out of your house or car, or from the ongoing falling temperatures experienced after nightfall while observing. This is important because faster temperature equalization means less time your telescope mirror spends "warped" from the rising and falling temperatures around your scope.
* Thin plate glass mirror blanks are lighter than standard mirror blanks, which allows you more flexibility in designing your telescope tube assembly and mount.
* When grinding a telescope mirror, you will find that plate glass takes less time to grind and polish than a mirror made from borosilicate glass.
Please see our Buy Telescope Mirror Blanks page for our extremely low prices on plate glass mirror blanks.