· Get a Cloudy Nights T-Shirt · Submit a Review / Article    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] Forum Archives · Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Equipment Discussions >> ATM, Optics and DIY Forum Previous   Index   Next   Threaded   Pages: 1 cnchillstar super member Reged: 12/29/08 Posts: 102 beginner questions, don't kill me~~~~~       #3358856 - 09/26/09 10:58 PM Edit   Reply   Quote Quick Reply   I think I have to ask some beginner questions but what is very important to me..... 1.is there a commercial supplier who make spider like obsession UC? http://www.obsessiontelescopes.com/telescopes/22_UC/okie-tex-shots/7169.jpg 2.does a newtonian on GEM need field rotater? 3.how is a classical cassegrain focus? on secondary(OMI scope) or back? what is the difference 4.what is back focus for cassegrian? distance between x to x? 5.what is FLI focuser function? it looks very stange to me as a FOCUSER. 6.if I want to mount meade DSI to my newtonian scope, how many milimeter should be left out of the top plane of focuser? thanks for great patiece~~~~ Post Extras:       HiggsBoson Pooh-Bah Reged: 02/21/07 Posts: 1118 Loc: Kal-li-fornia Re: beginner questions, don't kill me~~~~~ [Re: cnchillstar]       #3358940 - 09/27/09 12:07 AM Edit   Reply   Quote Quick Reply   Hello cnchillstar I am only able to tell you that a telescope on a GEM does not require a field rotator. I do not know how classical cassegrains were focused. I would presume one can use a standard crayford focuser. Some people focus their SCTs this way to avoid the change in image scale cause my moving the primary mirror in a commercial SCT. It also allows one to use a motorized focuser which is helpful for astrophotography. -------------------- Michael ATM: 6" F/9 Newtonian Travel Scope ATM: 12.5" F/4.5 Real Soon Now... Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 8 registered and 4 anonymous users are browsing this forum. Moderator:  Don W, Mike I. Jones  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 169 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 and Intermediate Imaging   Film Astrophotography   DSLR & Digital Camera Astro Imaging & Processing   CCD Imaging & Processing   Solar System Imaging & Processing   Sketching   Astro Imaging/Sketching Contest *Observing* -----   NEO   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 CN Forums Home

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