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Home > Forums > ASTRONOMY > Beginning Astronomy? > Message #836518

Re: barlow basics

Posted by Thomas Dey on 11/11/2017 4:45 PM in response to Re: barlow basics   (78 hits)
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Hi, Chris, Enjoying your good questions and interest in things astronomical/optical. Regarding mirror materials: Various glasses have been favored for a long time now. Desired properties are workability, homogenity, isotropy, low stress, thermal props, chem props, availability and COST. Fine-annieled Pyrex (i.e. borosilicate glass) is a nice choice, because it is relatively cheap, and much lower CTE than other glasses. Fused Silica (Quartz) is wonderful, but expensive. And exotics, like CERVIT, ULE, Zerodur... are used in optic test sets and satellites. Some exotic metal mirrors are used in satellites, e.g. beryllium, where mech, weight and thermal are paramount. For hobby-fab, I would recommend sticking to the available "standard" stuff, especially if starting out. Making mirrors at home is FUN! PS The BIG GUYS have spent vast $$$ and time developing ~cast mirrors~... with limited success. That would be great fun to experiment with, for a hobby. But, I would expect to have a lot of fun making something that very likely will not work well. But, that's no reason to not try! I highly recommend making a plain, vanilla 6-inch telescope mirror first! Tom

29-inch Dob in a dome
36-inch upgrade soon
LUNT 80/80 solar scope
FLI 6803 cam
APM 100mm APO Binos
JMI RB-16 Night Vision Binos
Zeiss 20x60 IS binos


Subject Posted By Date/Time Hits 
barlow basics Chris Kelly 10/28/2017 5:52 AM 119
Re: barlow basics Ed Blankenship 11/1/2017 9:04 PM 94
Re: barlow basics Ed Blankenship 11/1/2017 9:31 PM 66
Re: barlow basics Chris Kelly 11/2/2017 9:57 AM 84
Re: barlow basics Ed Blankenship 11/5/2017 3:51 PM 70
Re: barlow basics Ed Blankenship 11/5/2017 3:58 PM 77
Re: barlow basics Ed Blankenship 11/5/2017 4:31 PM 71
Re: barlow basics Chris Kelly 11/11/2017 8:19 AM 75
Re: barlow basics Thomas Dey 11/11/2017 4:45 PM 78
Re: barlow basics Chris Kelly 11/13/2017 6:44 AM 60

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