Loading ...
Sorry, an error occurred while loading the content.
 

45 deg Erect-Image Prism

Expand Messages
  • Bob
    Hi all I have recently bought a Meade 45deg Erect-Image Prism, for use on my ETX105. When in use I have found that at high angles, the prism fouls the base of
    Message 1 of 5 , Feb 3, 2013
      Hi all I have recently bought a Meade 45deg Erect-Image Prism, for use on my ETX105. When in use I have found that at high angles, the prism fouls the base of the scope. Is this normal as would have thought seeing as they are both Meade, this would not happen.
      Any thoughts Bob.
    • Rod Mollise
      Why do you need an erect image prism for a 105? It s image is already right side up? I suspect the reason Meade did not make provisions for it was they didn t
      Message 2 of 5 , Feb 3, 2013
        Why do you need an erect image prism for a 105? It's image is already right
        side up? I suspect the reason Meade did not make provisions for it was they
        didn't think it would be useful for this telescope.


        Uncle Rod Mollise
        Contributing Editor Sky and Telescope Magazine
        Uncle Rod's Astroblog:
        <http://uncle-rods.blogspot.com>



        -----Original Message-----
        From: ETXASTRO@yahoogroups.com [mailto:ETXASTRO@yahoogroups.com] On Behalf
        Of Bob
        Sent: Sunday, February 03, 2013 4:48 AM
        To: ETXASTRO@yahoogroups.com
        Subject: [ETXASTRO] 45 deg Erect-Image Prism

        Hi all I have recently bought a Meade 45deg Erect-Image Prism, for use on my
        ETX105. When in use I have found that at high angles, the prism fouls the
        base of the scope. Is this normal as would have thought seeing as they are
        both Meade, this would not happen.
        Any thoughts Bob.



        ------------------------------------

        Yahoo! Groups Links
      • Stan Stocker
        Hi Bob, It s been years since I played around with this on an ETX 90, but I think that the problem exists in alt-az but not in polar alignment. Most often the
        Message 3 of 5 , Feb 3, 2013
          Hi Bob,

          It's been years since I played around with this on an ETX 90, but I
          think that the problem exists in alt-az but not in polar alignment.
          Most often the desire for a "top up" view is for terrestrial rather than
          astro use.

          Take care,
          Stan

          On 02/03/2013 05:48 AM, Bob wrote:
          > Hi all I have recently bought a Meade 45deg Erect-Image Prism, for use on my ETX105. When in use I have found that at high angles, the prism fouls the base of the scope. Is this normal as would have thought seeing as they are both Meade, this would not happen.
          > Any thoughts Bob.
        • autostaretx
          The Erect-Image prism is intended for use in the rear port *when the scope is mounted as a spotting scope , without the motorized base assembly. If you point
          Message 4 of 5 , Feb 3, 2013
            The Erect-Image prism is intended for use in the rear port *when the scope is mounted as a "spotting scope", without the motorized base assembly.

            If you point the scope "straight up", you'll see one or two 1/4-20 holes on the flat surface "under" the normal top-of-barrel eyepiece holder.
            Those holes are intended for direct mounting on to a typical pan/tilt photographic tripod head. (you would have to remove the entire Optical Tube Assembly (OTA) from the forks of the base to achieve that).

            Meade sold the ETX-90/105/125 in a "spotting scope" configuration for about $200 less than the more typical astro-mount. That's the model the erect image prism was intended for...

            As others have said, you can see an "erect" image by using the "normal" eyepiece holder on the top of the scope... yes, it's a little more of a neck-bend to do that, but it's all you "need".
            (maybe not what you "want", but life is a series of compromises)

            Even with an erect image prism, you'll still have left/right reversal, so reading distant billboards will still be difficult.

            Of course, you could put the erect image prism in the normal top-of-scope eyepiece holder, but pointed "sideways".. that would give you the erect image from the flip-mirror, and the right/left correction of the prism.. and you'd have a fully corrected terrestrial scope, and the top-mounted prism would not hit things during slewing.
            Training yourself to aim the scope while "facing sideways" will become amusing...

            have fun
            --dick

            --- In ETXASTRO@yahoogroups.com, "Bob" wrote:
            >
            > Hi all I have recently bought a Meade 45deg Erect-Image Prism, for use on my ETX105. When in use I have found that at high angles, the prism fouls the base of the scope. Is this normal as would have thought seeing as they are both Meade, this would not happen.
            > Any thoughts Bob.
            >
          • Brian Straight
            Sometimes Meade does not think things through too well. I have a 14 inch ACF with the Meade series 5000 prism and 2 inch (25mm?) eyepiece. The visual back on
            Message 5 of 5 , Feb 3, 2013
              Sometimes Meade does not think things through too well.  I have a 14 inch ACF with the Meade series 5000 prism and 2 inch (25mm?) eyepiece.  The visual back on the scope is so long that you can't move the eyepiece to the vertical position.

              Brian

              Brian Straight
              Walnut Ridge Observatory


              On Sun, Feb 3, 2013 at 2:02 PM, autostaretx <rseymour@...> wrote:
               

              The Erect-Image prism is intended for use in the rear port *when the scope is mounted as a "spotting scope", without the motorized base assembly.

              If you point the scope "straight up", you'll see one or two 1/4-20 holes on the flat surface "under" the normal top-of-barrel eyepiece holder.
              Those holes are intended for direct mounting on to a typical pan/tilt photographic tripod head. (you would have to remove the entire Optical Tube Assembly (OTA) from the forks of the base to achieve that).

              Meade sold the ETX-90/105/125 in a "spotting scope" configuration for about $200 less than the more typical astro-mount. That's the model the erect image prism was intended for...

              As others have said, you can see an "erect" image by using the "normal" eyepiece holder on the top of the scope... yes, it's a little more of a neck-bend to do that, but it's all you "need".
              (maybe not what you "want", but life is a series of compromises)

              Even with an erect image prism, you'll still have left/right reversal, so reading distant billboards will still be difficult.

              Of course, you could put the erect image prism in the normal top-of-scope eyepiece holder, but pointed "sideways".. that would give you the erect image from the flip-mirror, and the right/left correction of the prism.. and you'd have a fully corrected terrestrial scope, and the top-mounted prism would not hit things during slewing.
              Training yourself to aim the scope while "facing sideways" will become amusing...

              have fun
              --dick



              --- In ETXASTRO@yahoogroups.com, "Bob" wrote:
              >
              > Hi all I have recently bought a Meade 45deg Erect-Image Prism, for use on my ETX105. When in use I have found that at high angles, the prism fouls the base of the scope. Is this normal as would have thought seeing as they are both Meade, this would not happen.
              > Any thoughts Bob.
              >


            Your message has been successfully submitted and would be delivered to recipients shortly.