Click here if you are having trouble logging into the forums Cloudy Nights - Official Forums of the 2009 International Year of Astronomy Privacy Policy | Please read our Terms of Service | Signup and Troubleshooting FAQ | Problems? PM a Red or a Green Gu.... uh, User   You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Flat   DSalters sage Reged: 03/03/07 Posts: 438 Loc: High Ridge, MO (St. Louis) Re: Is this an example of offsetting?       07/03/08 06:00 PM Edit   Reply   Quote   Quick Reply:   In Newtonian telescopes when the secondary is placed out of the light path (such as a Herschelian telescope), you have to have the primary's focal length be long enough to make the aberrations unnoticed. In that case, isn't having an extreme offset going to eventually introduce these aberrations even if the scope is properly collimated? Daniel -------------------- 6" f/8 Bushnell Voyager Dob. Rebuild 10" f/5 Highe Dob. variant (UNDER CONSTRUCTION: 5" f/5, 8" f/6, 13" f/4.6) Baader Hyperions--Primary Eyepieces "The sun has one kind of splendor, the moon another and the stars another; and star differs from star in splendor." -1 Corinthians 15:41 Post Extras       Entire thread Subject Posted by Posted on Is this an example of offsetting? DSalters 07/02/08 06:15 PM Re: Is this an example of offsetting? Jason D   07/02/08 09:59 PM Re: Is this an example of offsetting? DSalters   07/03/08 06:00 PM Re: Is this an example of offsetting? DSalters   07/03/08 06:03 PM Re: Is this an example of offsetting? Vic Menard   07/03/08 07:47 PM Re: Is this an example of offsetting? Houdini   07/02/08 08:08 PM Extra information 8 registered and 12 anonymous users are browsing this forum. Moderator:  Don W, Joe Cipriano  Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Rating: Thread views: 231 Jump to *International Year of Astronomy 2009* -----   Global Coordination   Cornerstone Projects   Special Projects   Special Task Groups   Global Activities   National and Regional Activities   IYA 2009 in Africa   IYA 2009 in the USA*Announcements and News* -----   Cloudy Nights Announcements   Discussion of CN Articles, Reviews, and Reports   Beginners Forum   Celestial Events   Light Pollution*Equipment Discussions* -----   ATM, Optics and DIY Forum   Binoculars   Binoviewers   Cats & Casses   Classic Telescopes   Equipment   Eyepieces   Mounts   Observatories   Reflectors   Refractors    Celestron SkyScout and Meade mySky   Video and Electronically Assisted Astronomy*Astrophotography and Sketching* -----   Beginning Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   General Observing   Planetary and Solar System Observing   Lunar Observing   Deep Sky Observing   Double Star Observing   Solar   Variable Star Observing and Radio Astronomy*Telescope Specific Forums* -----   Celestron NexStar    NexStar GPS / CPC Telescopes   Questar Forum   Meade ACF/RCX / LX / GPS    Meade ETX*Other* -----   Science of Astronomy & Space exploration   AstroWebsites   Space Rocks*Speciality Forums* -----   AstroArt   Astronomy Software & Computers   Stellar Media   Astro Outreach, Clubs and Star Parties*CN Feedback and Vendor Announcements* -----   Vendor and Group Announcements Home

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