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RE: [ccd-newastro] Equipment dilema :-(

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  • Ron Wodaski
    Imaging is the more challenging task, so I ll only consider it when making a recommendation here. The key question here is what focal length do you want to
    Message 1 of 53 , Apr 2, 2002
      Imaging is the more challenging task, so I'll only consider it when making a
      recommendation here.

      The key question here is what focal length do you want to image at? Are you
      interested in wide-field imaging -- then the FSQ-106 is probably the best
      choice and it will work on almost any competent imaging-grade mount (EM-10;
      EM-200; NJP; AP 400 GTO, etc.). Is portability the critical issue? Then the
      Sky90 is smaller and lighter, and with the f/4.5 field flattener it works
      very well with CCD cameras.

      Do you want to "go long" and use a longer focal length so that you can take
      portraits of deep-sky objects? If you want a longer focal length, say
      1000mm, then a 5" or 6" refractor is your ticket. A 5" refractor will get to
      1000mm at about f/7 or f/8, and run between $4-6k, squeezing you somewhat on
      the mount. The Tak FS-128 (or a used FC-125) would be ideal and have a nice
      large flat field. The AP130 would also work well with the size of the chip
      in your current camera, but starts showing elongation from curvature of
      field with chips like the KAF-1602 and KAF-3200. I would look at the EM-200,
      a used AP 900 GTO, and a Mountain Instruments MI-250 as your primary options
      for mounting a 5" refractor for imaging.

      If a 5" refractor pushes the budget too hard, then a 4" will have to do it.
      Your choice is either among the fast wide-field scopes previously mentioned
      (to which one could add scopes like the TV NP101 and various TMB scopes),
      or an f/7 to f/8 4" or smaller refractor that will give you longer focal
      lengths and a narrower field of view (FS-102, TV 85, etc.). You'll need
      longer exposures with the slower focal ratio, but anything f/10 or under is
      reasonable with CCD cameras.

      Ron Wodaski
      author of The New CCD Astronomy

      -----Original Message-----
      From: audibeasta42001 [mailto:dan.sevcenco@...]
      Sent: Tuesday, April 02, 2002 7:36 AM
      To: ccd-newastro@yahoogroups.com
      Subject: [ccd-newastro] Equipment dilema :-(

      Hello all,

      I am having an equipment dilema and I would appreciate any advice you
      can give me on this one, as it is "killing" me :-)

      Here is the data:

      * Budget: $10,000
      * Want a refractor on an equatorial mount intended for both visual
      and CCD use. I'd say about 50% of the time for each.
      * The CCD camera is not part of the budget as I already have it (FLI
      MaxCam 7)
      * The budget must include the OTA, mount, tripod / pier and anything
      else that is neccessary - field flattener, dovetail and rings for
      mounting the OTA, etc.

      So, given the above, which would be the configuration you would
      choose, in terms of brand, model and price distribution per item.


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    • richardmjordan
      Hi Dan, Another scope for serious consideration if the Vixen 114m f/5.3 ED apo refractor. With the I have one and I m sure you saw its review in the most
      Message 53 of 53 , Apr 8, 2002
        Hi Dan,
        Another scope for serious consideration if the Vixen 114m f/5.3 ED
        apo refractor. With the I have one and I'm sure you saw its review
        in the most recent S&T. It is a great scope and the cost is about
        $2000 (I got mine for $1850). You can get it from Orion or perhaps
        another international dealer. Its forte is wide field
        astrophotography, but it is a wonderful visual scope as well. An
        option is an f/4.4 focal reducer for photography. The Vixen gives
        great wide field views and no color on the Moon, Jupiter or Saturn.
        The S&T review was accurate and fair (and I think very favorable for
        the Vixen), but there was one point of possible misunderstanding.
        The reviewer noted that a number of his eyepieces did not come focus.
        I have many premium oculars (Naglers 3 to 6 zoom, 7mm and 9 mm Type
        6, 17 mm and 20mm; Orion SW Lanthanum, Pentax XL, UO 40 and 25 mm
        Konigs MK70, All UO 1.25 Konigs; 6mm through 55 mm Clave Plossls from
        the late 1970s)and a number of other mid level eyepieces. WITHOUT the
        field flattener (not needed for visual use) and WITH a 2 inch
        diagonal they all easily come to a beautiful focus. I don't have
        Panoptic but a post on the Vixen Yahoo group after the review
        appeared from a reliable source indicated that the 35mm Panoptic also
        comes to focus with the above configuration. I think all eyepieces
        will come to focus using a 2 inch diagonal and no field flattener
        (just screws in and out very easily). The reviewer noted that the 2
        inch set-up was the best, but I was left with the impression that
        this was a real problem, which it really isn't. I have both a
        Losmandy G11 and GM8 mount and an SBIG STV which is mated for the
        Losmany controls and autoguiding. A pier is available. Both of the
        mounts are excellent. The G11 is better for imaging but GM8 is
        somewhat more portable. With you budget, however, you probably can go
        to an even higher quality. BTW Vixen has another, supposedly ever
        higher quality, apo available - a double ED (DED series). It comes
        in 108mm f/5 and I believe a 130mm (not sure of the f/# but it is
        probably f/5 as well). For what its worth the DED had a very
        positive post on the Vixen Yahoo group. With these items, I have
        used about 1/2 of your budget.

        Rick Jordan
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