RE: [Utah-astronomy] Lasers and collimation questions
Couldn't one collimate with a centered secondary with a center dot then simply offset afterwards the required amount, or will that screw-up the collimation? -----Original Message----- From: Chuck Hards [mailto:chuckhards@yahoo.com] Sent: Tuesday, August 12, 2003 9:00 PM To: Visit http://www.utahastronomy.com for the photo gallery. Subject: RE: [Utah-astronomy] Lasers and collimation questions Someone earlier in this thread mentioned a secondary mirror template for center-dotting purposes. Remember that if you have a fast system, the diagonal will not be centered. It must be off-centered slightly in order to provide an evenly illuminated focal plane. Hopefully the template will take this into account, I'm not familiar with the book mentioned. C. __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com _______________________________________________ Utah-Astronomy mailing list Utah-Astronomy@mailman.xmission.com http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy
The diagonal is actually shifted in the plane of it's reflecting surface, so unless your secondary holder is constructed specifically to allow that 'sliding' motion, in the plane of the secondary ONLY, collimation will suffer. I've never seen a commercial diagonal holder with such adjustment capability. What is usually done is to de-center the spider by the required amount, then move the diagonal axially toward the primary until it's back in the proper plane. Looking through the focuser, the diagonal will appear off-center (it is, physically) even though the telescope is fully collimated. Can be a conceptual stumbling-block. C. --- Kim Hyatt <khyatt@smithlayton.com> wrote:
Couldn't one collimate with a centered secondary with a center dot then simply offset afterwards the required amount, or will that screw-up the collimation?
-----Original Message----- From: Chuck Hards [mailto:chuckhards@yahoo.com] Sent: Tuesday, August 12, 2003 9:00 PM To: Visit http://www.utahastronomy.com for the photo gallery. Subject: RE: [Utah-astronomy] Lasers and collimation questions
Someone earlier in this thread mentioned a secondary mirror template for center-dotting purposes. Remember that if you have a fast system, the diagonal will not be centered. It must be off-centered slightly in order to provide an evenly illuminated focal plane. Hopefully the template will take this into account, I'm not familiar with the book mentioned.
C.
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participants (2)
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Chuck Hards -
Kim Hyatt