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20343Re: Need focal reducer help!

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  • uwpf23
    Dec 2, 2003
      Thanks for the info Jim!

      Clear skies,

      --- In ccd-newastro@yahoogroups.com, "Jim Thibert" <thibertj@h...>
      > I have found with all the ccd optical train, especially when using
      a c14and
      > st7 that .63 is tough enough let alone 3.3 R/C
      > For the .63, I went to a VSE focuser where the R/C is zero offset
      > its inside
      > Good skies-clear eyes
      > JImmy
      > http://www.forterieobservatory.com
      > formerly, www.frenchriverobservatory.com
      > W78-55-12 N42-54-25
      > C-14@f... (st7-i/cfw8)and TV101(st7-e) on ParamountME with VSE m-
      > ----Original Message Follows----
      > From: "uwpf23" <uwpf23@y...>
      > Reply-To: ccd-newastro@yahoogroups.com
      > To: ccd-newastro@yahoogroups.com
      > Subject: [ccd-newastro] Need focal reducer help!
      > Date: Mon, 01 Dec 2003 04:29:25 -0000
      > Hi,
      > I cannot achieve focus with a Meade F/3.3 focal reducer used with
      > the following:
      > 1) Celestron CGE-1400 OTA. 3910mm focal length @ F-11 when no focal
      > reducer used.
      > 2) CCD setup is an ST-7/CFW-8/AO-7 all attached together.
      > 3) JMI SmartFocus elecric micro-focuser.
      > I've tried the following already:
      > 1) Mounted the reducer directly onto the visual back of the OTA
      > then attached the JMI, then the CCD gear. Racked the Celestron
      > main focus knob all the way clockwise (mirror moved all the way
      > back toward the rear). The image was moving toward focus, but
      > could not get all the way focused.
      > 2) Mounted JMI focuser first, then the reducer, then the CCD gear.
      > Same result.
      > Note: I CAN get focus with the F/3.3 reducer through the eyepiece
      > a star diagonal visually (NO CCD attached).
      > Is my problem that the focal reducer lens is too far away from the
      > CCD chip with all the gear attached? Or, is it too close to the
      > chip? It seems from the visual eyepiece check that the reducer is
      > too far away from the CCD chip. I can't get it any closer without
      > removing some of the CCD attachments, which is not feasible for me
      > (can't do without the color wheel or adaptive optics).
      > Anybody have any ideas on what the cure for this is? If this
      > focal reducer is incompatible, anybody have any suggestions for
      > that will work and are faster than F/6.3 (already have a .63 from
      > Celestron that works fine--just need shorter focal lengths than
      > with such a long main focal length to work with!). Would like to
      > down to at least F/4 or 4.5 if possible, as F/6.3 just is not
      > desirable with some objects on the CGE-1400.
      > Thanks for any help you all can give me on this!
      > Clear skies,
      > Wade Van Arsdale
      > Little Rock, AR.
      > (Registered NewAstro Customer)
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