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Re: RCX400 f/8 and Focal Reducers

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  • glenn condie
    ... your vignetting ,it will not remove the defects introduced with that FR you are using ie it s for an F10 SCT . Toss the focal reducer ,dial in your AO
    Message 1 of 8 , Jan 2, 2009
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      --- In RCX400@yahoogroups.com, Hi Rod Flat Fielding will remove
      your vignetting ,it will not remove the defects introduced with that
      FR you are using ie it's for an F10 SCT . Toss the focal
      reducer ,dial in your AO unit you can image at F8 all day long!
      Rememeber if you can get through 8 minutes you can go as long as you
      want because this is the time nessasary to successfully remove the
      periodic error to acceptable levels.Balance your scope ,Get polar
      alignment set up. Good Luck PS. Pempro has a steep learning
      curve but is excellent for analysing your mount !
      Glenn

      "rcx400" <rodsrun@...> wrote:
      >
      > I know that everybody recommends FRs for astro-imaging to reduce
      > exposure times, increase field of view, and flatten the peripheral
      > field of view (which isn't supposed to be necessary with the RCX400
      > scopes). Old threads I've read, and participated in, describe the
      FR
      > pros and cons in detail. But is anyone here imaging using an f/8
      > RCX400 without a FR?
      >
      > I ask because I'm experiencing fairly extreme vignetting using the
      Ted
      > Agos' Antares 0.63 FR optics integrated into the tube adapter when
      used
      > in front of a AO-8, CFW-8A, and ST2000XM imaging train. With the
      FR in
      > place, I have an effective f/5 optical system, and without the FR I
      am
      > approximately back to the scope's OEM f/8.
      >
      > I'm going to try the non-FR arrangement to see what difference it
      makes
      > to the images I capture, and to my field of view, but I was
      wondering
      > what other's experiences have been without a FR on these scopes.
      >
      > Thanks for any real-world anecdotes provided.
      > Rod
      >
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