You are not logged in. [Login] Entrance · Main Index · Search · New user · Who's Online FAQ · Calendar Astrophotography and Sketching >> Film Astrophotography Previous   Index   Next   Threaded   Pages: 1 He-Man member Reged: 11/22/07 Posts: 17 Finderscope       #2077127 - 12/27/07 01:05 PM Edit   Reply   Quote Quick Reply   Hello everyone, I just wanted to know if it is possible to use a 8x40 or 9x50 illuminated finderscope as a guidescope for an Orion 80mm short tube. Thanks. Post Extras:       s58y Post Laureate Reged: 12/12/04 Posts: 4832 Loc: Eastern NY Re: Finderscope [Re: He-Man]       #2077210 - 12/27/07 01:49 PM Edit   Reply   Quote Quick Reply   Is that for manual guiding or autoguiding? For autoguiding, backfocus can be a problem with some finderscopes (assuming the eyepiece is removable). -------------------- Hutech 30D, SBIG ST-402 autoguider SV80S, SV66 guidescope AP900, G-11, Barndoor tracker http://www.pbase.com/s58y Post Extras:       He-Man member Reged: 11/22/07 Posts: 17 Re: Finderscope [Re: s58y]       #2077229 - 12/27/07 01:56 PM Edit   Reply   Quote Quick Reply   Manual guiding for galaxies and nebulae. Post Extras:       Suk Lee Post Laureate Reged: 10/07/03 Posts: 4314 Loc: Pleasanton, CA Re: Finderscope [Re: He-Man]       #2077234 - 12/27/07 02:01 PM Edit   Reply   Quote Quick Reply   A finder is going to be far too short in focal length to guide with. You typically want a guidescope that is 2x the focal length of your imaging scope at prime. You get to 2x by using similar focal length guidescope and a 12mm reticle eyepiece. That way any guiding errors will be smaller than the angular resolution (dot size) of a star on your film. Cheers, Suk -------------------- http://www.siliconvalleyskies.com Post Extras:       Pages: 1 Previous   Index   Next   Threaded   Extra information 0 registered and 1 anonymous users are browsing this forum. Moderator:  Suk Lee, Charlie Hein, knuklhdastnmr, ClownFish  Print Thread Forum Permissions       You cannot start new topics       You cannot reply to topics       HTML is disabled       UBBCode is enabled Thread views: 284 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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