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Re: Megrez 80 FD with Meade 0.63 focal reducer

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  • reim58
    Your setup sounds just like mine. I also use 5 pounds when I use my ETX90 as my guide scope. I have been using the same ring set to hold my Megrez 80 as the
    Message 1 of 9 , Jan 4, 2006
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      Your setup sounds just like mine. I also use 5 pounds when I use my
      ETX90 as my guide scope. I have been using the same ring set to hold
      my Megrez 80 as the ETX90. Its not a good fit since the rings are
      large and I can't get much adjustment on the plastic thumb screw for
      adjusting the 80mm scope. What rings to you use to hold the Megrez
      scope and also do you use the DSI as a standalone autoguider (ie, no
      laptop). I use a Meade 208 as a autoguider and I use it in
      standalone mode. I like this feature but the 208 did take some
      getting use to (its not the easiest thing to operate).

      Bob

      --- In William-Optics@yahoogroups.com, "Stephen Hamilton"
      <shamilton@h...> wrote:
      >
      > You are absolutely correct about the 3.3. My assumption was that
      this was created when CCD chips were still commonly very small and as
      is still true with many of the intro CCDs such as the SAC8, DSI,
      etc. My 416XTE, not that much larger then my DSI causes definite
      vingetting with the 3.3 unless it is used with no (or 15mm)
      extensions only effectively making it a .5, not 3.3. You need to be
      pretty close to the chip to use it with anything larger then 1/3"
      CCDs in my opinion. I have used it with the Megrez also and get a
      very wide field but had other not so nice issues to deal with. With
      a DSLR, it is pretty much out all together.
      >
      > I run between 5 and 7.5 pounds on the LX90 depending on the setup.
      The Megrez weighs a bit more then my ETX90 so if I am guiding, I use
      the ETX and probably only need 5 pounds. With the Megrez on there, I
      use 7.5 simply due not only to its weight but length; I can only set
      it back on the scope so far.
      >
      > The LPI works fine for guiding, especially with the new Envisage.
      Still, due to it lower sensitivity, you either need to go longer on
      your guide exposures or use brighter stars. My DSI-Pro (or the
      regular DSI) definitely makes a better guider due to its sensitivity,
      but I have used the LPI quite often and since I generally use guide
      exposures of 1-2 seconds, I've never really had many problems with
      finding a suitable guide star. Except around M51; heaven help me, I
      don't think there ARE any stars around that thing LOL.
      >
      > Stephen P. Hamilton
      > http://astro.hcadvantage.com
      > 36° 45' 28" , -76° 15' 40"
      >
      >
      > -----Original Message-----
      > From: reim58 [mailto:reim58@y...]
      > Sent: Tuesday, January 03, 2006 10:39 PM
      > To: William-Optics@yahoogroups.com
      > Subject: [William-Optics] Re: Megrez 80 FD with Meade 0.63 focal
      reducer
      >
      >
      > Hi Stephen,
      > I see you also use a LX90. How does the LPI work as an
      autoguider?
      > It took me 7.5 pounds to get my LX90 balanced. How much did you
      > use for that shot?
      >
      > Focal Reducer: I was quite impressed with how well the .63 reducer
      > did. I plan on using this setup quite a bit now. I have used the
      > F3.3 reducer on my LX90 and the vignetting was very bad.
      >
      > Vignetting link
      > http://www.pbase.com/reim58/image/25797670
      >
      > Now this vignetting really shows up since I am using a DSLR which
      > has a large chip. If you using a small chip for imaging then you
      > might not notice it that much.
      >
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