Loading ...
Sorry, an error occurred while loading the content.

Short focal length guider question

Expand Messages
  • Robert
    Is it plausible that guiding with a relatively shorter focal length guidescope could help in situations/locations with poor seeing? TIA Bob Hertel
    Message 1 of 4 , Aug 1, 2010
    View Source
    • 0 Attachment
      Is it plausible that guiding with a relatively shorter focal length guidescope could help in situations/locations with poor seeing?
      TIA
      Bob Hertel
    • Bill Shaheen
      Robert - I think you would be amazed how well a 50mm finderscope guides. Here s a recent image taken with an EdgeHD 9.25 guided with a Stellarvue 50mm
      Message 2 of 4 , Aug 3, 2010
      View Source
      • 0 Attachment
        Robert - I think you would be amazed how well a 50mm finderscope guides.

        Here's a recent image taken with an EdgeHD 9.25 guided with a Stellarvue 50mm finderscope and a Starlight Xpress Lodestar autoguider:
        http://www.pbase.com/wjshaheen/image/127114189/large

        Although I did use a 2x Barlow, many users in the autoguiding group insist that is even not necessary.

        Bill Shaheen
        Gold Canyon, AZ
        USA

        --- In ccd-newastro@yahoogroups.com, "Robert" <robert.hertel@...> wrote:
        >
        > Is it plausible that guiding with a relatively shorter focal length guidescope could help in situations/locations with poor seeing?
        > TIA
        > Bob Hertel
        >
      • tekic545
        Bob, Unless you re using very short exposures, you ll probably need to guide regardless of seeing conditions. Small guidescopes work just fine on larger
        Message 3 of 4 , Aug 3, 2010
        View Source
        • 0 Attachment
          Bob,

          Unless you're using very short exposures, you'll probably need to guide regardless of seeing conditions. Small guidescopes work just fine on larger imaging scopes, providing the ratio of the two imaging scales is not wildly different.

          I use a 60 mm guidescope with a Starfish (1.3 mpx, each 5.2 microns) that gives me a guiding image scale of 3.4 arc-sec/pixel.
          This is about three times the image scale of the 12-inch f/3.6 scope, and guiding is perfect. The ratio could be larger and it would still work fine.

          Here's a 200-minute example: http://tinyurl.com/2dez3py

          Regards, Bob Gillette


          --- In ccd-newastro@yahoogroups.com, "Robert" <robert.hertel@...> wrote:
          >
          > Is it plausible that guiding with a relatively shorter focal length guidescope could help in situations/locations with poor seeing?
          > TIA
          > Bob Hertel
          >
        • Neil Fleming
          In poor seeing you can also choose to go a little longer with your guide cam exposures.  Although still not as good as when you have great seeing, 4-10
          Message 4 of 4 , Aug 3, 2010
          View Source
          • 0 Attachment
            In poor seeing you can also choose to go a little longer with your guide cam
            exposures.  Although still not as good as when you have great seeing, 4-10
            second shots should average out the seeing fluctuations well.  Most mounts can
            handle that and longer...

               ...Neil
             
            www.flemingastrophotography.com 
            Direct from Boston - brilliant diamonds in pea soup
            Also check out the astro_narrowbandYahoo group!




            ________________________________
            From: tekic545 <tekic545@...>
            To: ccd-newastro@yahoogroups.com
            Sent: Tue, August 3, 2010 11:17:50 AM
            Subject: [ccd-newastro] Re: Short focal length guider question

            Bob,

            Unless you're using very short exposures, you'll probably need to guide
            regardless of seeing conditions. Small guidescopes work just fine on larger
            imaging scopes, providing the ratio of the two imaging scales is not wildly
            different.

            I use a 60 mm guidescope with a Starfish (1.3 mpx, each 5.2 microns) that gives
            me a guiding image scale of 3.4 arc-sec/pixel.
            This is about three times the image scale of the 12-inch f/3.6 scope, and
            guiding is perfect. The ratio could be larger and it would still work fine.

            Here's a 200-minute example: http://tinyurl.com/2dez3py

            Regards, Bob Gillette


            --- In ccd-newastro@yahoogroups.com, "Robert" <robert.hertel@...> wrote:
            >
            > Is it plausible that guiding with a relatively shorter focal length guidescope
            >could help in situations/locations with poor seeing?
            > TIA
            > Bob Hertel
            >




            ------------------------------------




            [Non-text portions of this message have been removed]
          Your message has been successfully submitted and would be delivered to recipients shortly.