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8128Zenithstar 80 APOgrade steps......

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  • dsi_pro_wangler
    Mar 23 6:29 PM
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      Per a request, here are some basic steps to follow when upgrading
      the ZS80:

      1) The original ZS80 cell is reached by first fully retracting the
      dew shield:
      -There is a small plastic ring at the tip of the dew shield, which
      acts as a retraction stop.
      -Carefully grasp the plastic ring, with finger tips on the inside
      of the dewshield if needed.
      -With the retraction stop removed, the dewshield can be retracted
      as far as possible, until it bottoms out on the OD step of the OTA.
      2) The original doublet cell should be clearly visible, as should
      the end of the OTA that the cell is threaded into:
      -Carefully grasp the outside of the cell, and begin to unscrew the
      original cell.
      -The original cell should come out, and you will see that the cone
      baffle is attached to the cell.
      -Pull out the cell baffle assembly, and lay the OTA aside.
      3) The cone baffle acts as a retaining ring for the original
      doublet, so be careful when unthreading, as not to drop the original
      objective doublet!!
      -Grasp the baffle/cell assembly, with the baffle pointing straight
      up.
      -Unscrew the cone baffle from the original cell, and carefully set
      the cell aside: warning: the original objective is loose in the
      cell, be careful!
      4) Carefully screw the cone baffle into the new objective cell.
      -Rethread the baffle onto the new APO cell, careful not to
      overtighten.
      5) Reverse the order of step #2 with the new APO cell and baffle
      assembly.
      6) Reverse the order of step #1 to reattach the dew shield retention
      stop ring.
      7) Pray for clear skies.


      As for vignetting, the only brief check I performed was verification
      that I could see a very little bit of the new APO cell at the front
      of the new doublet, by looking through the focus tube fully
      retracted and fully extended. It was close, but I could see either
      the cell or the tip of a finge held over the edge of the APO
      objective in either case: effectively no vignetting based upon this
      non-scientific test.

      Hope that this helps, and enjoy your new 80mm APO flourite doublet!!

      Keith