Telescope Information Request:
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Seme
Posted:
Thu Apr 12, 2007 3:02 am
Joined: 12 Apr 2007
Posts: 1
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Telescope Information Request:
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If the aperture is the diameter of the objective, what is the name for the opening at the front of a reflector telescope which allows the light to enter the barrel or tube of the telescope, and what is the formulation of the size of this opening relative to the aperture?
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Marc
Site Admin
Posted:
Sun Apr 15, 2007 10:33 am
Joined: 24 Oct 2003
Posts: 108
Location: Ireland
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Unless you're planning to create some kind of collapsible tube the diameter of the opening would be the same as the aperture. For definitive answer see the next reply
I must admit, I have no idea what the name is, if there is one, for the opening at the top of reflector telescopes!
Last edited by Marc on Sun Apr 15, 2007 2:26 pm; edited 1 time in total
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ray cash
Posted:
Sun Apr 15, 2007 2:18 pm
Joined: 15 Apr 2007
Posts: 1
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The "inside diameter" of the tube of a Newtonian reflector must be 1-1/2" larger than the objective mirror. This space around the primary (around 3/4", in other words) is needed as a boundary layer to insulate the optics from "tube currents"--optically harmful waves caused by temperature differences from the ambient air and the tube material.
Ray Cash
San Francisco
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