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Televue Binoviewers and GT81FD

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  • pgabura
    I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81. It seems
    Message 1 of 10 , Jun 25, 2013
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      I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.

      It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?

      The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.

      I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.

      I have tried it both with and without the WO 2" diagonal.

      Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
    • pgabura
      My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10 Orion Dob for a few years and have a Celestron 6 SCT but this is
      Message 2 of 10 , Jun 25, 2013
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        My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10" Orion Dob for a few years and have a Celestron 6" SCT but this is my first purchase of a refractor. I want to get into astrophotography and was impressed with the sharp image and fast wide field performance of the WO short FL refractors.

        Based on research I decided to buy the GT81 to start on. I also have the FLT 132 on order and the iOptron iEQ45 mount.

        From reading other posts I have learned I should get the WO 2" tube for my T-ring and that Binoviewers are in general dificult to use on many telescopes. Perhaps these are the only answers available. Any additional insite would be greatly appreciated.

        Thanks

        Paul
        --- In William-Optics@yahoogroups.com, "pgabura" <psg@...> wrote:
        >
        > I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.
        >
        > It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?
        >
        > The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.
        >
        > I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.
        >
        > I have tried it both with and without the WO 2" diagonal.
        >
        > Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
        >
      • Timm B
        Hi Paul, The GTF102 that I have is similar in that it was optimized to be used for astrophotography so that the focuser wouldn t need a long extension for
        Message 3 of 10 , Jun 25, 2013
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          Hi Paul,

          The GTF102 that I have is similar in that it was optimized to be used for astrophotography so that the focuser wouldn't need a long extension for cameras.

          For visual use, you will probably need a 1.25" diagonal, any will do, but get a good dielectric like the WO one, and you will be happy. A 2" diagonal will push the eyepiece out much further in the optical path, and may not be able to reach focus.

          The trade off is that you will be able to easily reach focus with any camera. For your DSLR you will need a 2" photo adapter with the proper T-Ring attached. I like the one WO sells, but any other will work, which adds enough length to allow it to reach focus.

          I have the iEQ45 as well, and its my first GEM so its a bit of a learning curve for me, and with the long days right now I can really only get it out on weekends, and we haven't had many clear Fri or Sat night this summer. Look for the iOptron Yahoo groups and join them as well

          The binoviewer issue is related. Many refractors are too long to allow for the much longer optical path introduced by a binoviewer, so adding the barlow in front of it will sometimes help. The hitch is that you will definitely need that 1.25" diagonal, and even with that it still might not reach focus. I don't have a binoviewer, so I can't say for sure.

          If you need any help just let us know here, and we will try to help you as best we can.

          I'm almost done with a full review of the GTF102, and will post it here and on CloudyNights.com as soon as I can.

          Take care,

          Timm



          --- In William-Optics@yahoogroups.com, "pgabura" <psg@...> wrote:
          >
          >
          > My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10" Orion Dob for a few years and have a Celestron 6" SCT but this is my first purchase of a refractor. I want to get into astrophotography and was impressed with the sharp image and fast wide field performance of the WO short FL refractors.
          >
          > Based on research I decided to buy the GT81 to start on. I also have the FLT 132 on order and the iOptron iEQ45 mount.
          >
          > From reading other posts I have learned I should get the WO 2" tube for my T-ring and that Binoviewers are in general dificult to use on many telescopes. Perhaps these are the only answers available. Any additional insite would be greatly appreciated.
          >
          > Thanks
          >
          > Paul
          > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
          > >
          > > I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.
          > >
          > > It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?
          > >
          > > The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.
          > >
          > > I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.
          > >
          > > I have tried it both with and without the WO 2" diagonal.
          > >
          > > Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
          > >
          >
        • pgabura
          Thanks for the reply Timm, your information was helpful. I have ordered both items and will give them a try. I will join the iOptron group as I am sure I am
          Message 4 of 10 , Jun 25, 2013
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            Thanks for the reply Timm, your information was helpful. I have ordered both items and will give them a try.

            I will join the iOptron group as I am sure I am going to have questions.

            Paul

            --- In William-Optics@yahoogroups.com, "Timm B" <t.bottoni@...> wrote:
            >
            > Hi Paul,
            >
            > The GTF102 that I have is similar in that it was optimized to be used for astrophotography so that the focuser wouldn't need a long extension for cameras.
            >
            > For visual use, you will probably need a 1.25" diagonal, any will do, but get a good dielectric like the WO one, and you will be happy. A 2" diagonal will push the eyepiece out much further in the optical path, and may not be able to reach focus.
            >
            > The trade off is that you will be able to easily reach focus with any camera. For your DSLR you will need a 2" photo adapter with the proper T-Ring attached. I like the one WO sells, but any other will work, which adds enough length to allow it to reach focus.
            >
            > I have the iEQ45 as well, and its my first GEM so its a bit of a learning curve for me, and with the long days right now I can really only get it out on weekends, and we haven't had many clear Fri or Sat night this summer. Look for the iOptron Yahoo groups and join them as well
            >
            > The binoviewer issue is related. Many refractors are too long to allow for the much longer optical path introduced by a binoviewer, so adding the barlow in front of it will sometimes help. The hitch is that you will definitely need that 1.25" diagonal, and even with that it still might not reach focus. I don't have a binoviewer, so I can't say for sure.
            >
            > If you need any help just let us know here, and we will try to help you as best we can.
            >
            > I'm almost done with a full review of the GTF102, and will post it here and on CloudyNights.com as soon as I can.
            >
            > Take care,
            >
            > Timm
            >
            >
            >
            > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
            > >
            > >
            > > My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10" Orion Dob for a few years and have a Celestron 6" SCT but this is my first purchase of a refractor. I want to get into astrophotography and was impressed with the sharp image and fast wide field performance of the WO short FL refractors.
            > >
            > > Based on research I decided to buy the GT81 to start on. I also have the FLT 132 on order and the iOptron iEQ45 mount.
            > >
            > > From reading other posts I have learned I should get the WO 2" tube for my T-ring and that Binoviewers are in general dificult to use on many telescopes. Perhaps these are the only answers available. Any additional insite would be greatly appreciated.
            > >
            > > Thanks
            > >
            > > Paul
            > > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
            > > >
            > > > I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.
            > > >
            > > > It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?
            > > >
            > > > The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.
            > > >
            > > > I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.
            > > >
            > > > I have tried it both with and without the WO 2" diagonal.
            > > >
            > > > Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
            > > >
            > >
            >
          • pgabura
            Timm Just wanted to report back and let you know that your advice was spot on. I purchased both items you recommended and was able to get focus with both the
            Message 5 of 10 , Aug 5 5:08 PM
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              Timm

              Just wanted to report back and let you know that your advice was spot on. I purchased both items you recommended and was able to get focus with both the DSLR and the binoviewers.

              Thanks again for your help.

              Paul


              --- In William-Optics@yahoogroups.com, "pgabura" <psg@...> wrote:
              >
              > Thanks for the reply Timm, your information was helpful. I have ordered both items and will give them a try.
              >
              > I will join the iOptron group as I am sure I am going to have questions.
              >
              > Paul
              >
              > --- In William-Optics@yahoogroups.com, "Timm B" <t.bottoni@> wrote:
              > >
              > > Hi Paul,
              > >
              > > The GTF102 that I have is similar in that it was optimized to be used for astrophotography so that the focuser wouldn't need a long extension for cameras.
              > >
              > > For visual use, you will probably need a 1.25" diagonal, any will do, but get a good dielectric like the WO one, and you will be happy. A 2" diagonal will push the eyepiece out much further in the optical path, and may not be able to reach focus.
              > >
              > > The trade off is that you will be able to easily reach focus with any camera. For your DSLR you will need a 2" photo adapter with the proper T-Ring attached. I like the one WO sells, but any other will work, which adds enough length to allow it to reach focus.
              > >
              > > I have the iEQ45 as well, and its my first GEM so its a bit of a learning curve for me, and with the long days right now I can really only get it out on weekends, and we haven't had many clear Fri or Sat night this summer. Look for the iOptron Yahoo groups and join them as well
              > >
              > > The binoviewer issue is related. Many refractors are too long to allow for the much longer optical path introduced by a binoviewer, so adding the barlow in front of it will sometimes help. The hitch is that you will definitely need that 1.25" diagonal, and even with that it still might not reach focus. I don't have a binoviewer, so I can't say for sure.
              > >
              > > If you need any help just let us know here, and we will try to help you as best we can.
              > >
              > > I'm almost done with a full review of the GTF102, and will post it here and on CloudyNights.com as soon as I can.
              > >
              > > Take care,
              > >
              > > Timm
              > >
              > >
              > >
              > > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
              > > >
              > > >
              > > > My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10" Orion Dob for a few years and have a Celestron 6" SCT but this is my first purchase of a refractor. I want to get into astrophotography and was impressed with the sharp image and fast wide field performance of the WO short FL refractors.
              > > >
              > > > Based on research I decided to buy the GT81 to start on. I also have the FLT 132 on order and the iOptron iEQ45 mount.
              > > >
              > > > From reading other posts I have learned I should get the WO 2" tube for my T-ring and that Binoviewers are in general dificult to use on many telescopes. Perhaps these are the only answers available. Any additional insite would be greatly appreciated.
              > > >
              > > > Thanks
              > > >
              > > > Paul
              > > > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
              > > > >
              > > > > I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.
              > > > >
              > > > > It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?
              > > > >
              > > > > The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.
              > > > >
              > > > > I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.
              > > > >
              > > > > I have tried it both with and without the WO 2" diagonal.
              > > > >
              > > > > Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
              > > > >
              > > >
              > >
              >
            • Jim Hendricks
              Hello Everyone and thanks for providing me with a forum to understand Williams Optics scopes a bit better. I recently purchased a Megrez 72 and have been using
              Message 6 of 10 , Aug 6 2:58 PM
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                Hello Everyone and thanks for providing me with a forum to understand Williams Optics scopes a bit better.
                 
                I recently purchased a Megrez 72 and have been using it as a widefield scope for imaging the larger nebulae during the summer...and for the emerging M31 galaxy!
                 
                I want to get accurate focus for these objects (obviously)...and so I decided to build my own stepper motor controlled focusing attachment to replace the manual control.
                 
                 
                The body is made from an old router dust nozzle...I turned down a coupler from a piece of aluminium stock rod....and added a Chinese stepper motor...all fed into my master hub controller.....
                 
                 
                The initial setup worked but getting smooth motion from the stock WO dual speed stock focuser proved impossible. It seems that the planetary gear was very rough indeed.
                 
                Today I took delivery of a Lacerta Dual Speed Microfocuser....
                 
                 
                Obviously this is meant for a Skywatcher so the base doesn't fit directly but the shaft is the same diameter and so I removed the dual speed knob assembly and replaced the Williams Optics one on the Megrez and it worked perfectly. It was far smoother...no glitches whatever and the stepper motor attachment worked flawlessly.
                 
                Does anyone know why the original WO one is so very coarse. I believe I read somewhere (might have been this forum)....that others were experiencing the same problems with a roughness in focusing. Any comments.....views?
                 
                Jimi
              • twinklescope
                Hi Timm; I m Roger and I m new to the group. I m just a visual observer not into AP yet. I was considering the GTF 81 because it seems like a quality
                Message 7 of 10 , Aug 12 12:02 PM
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                  Hi Timm;    I'm Roger and I'm new to the group.    I'm just a visual observer not into AP yet.   I was considering the GTF 81 because it seems like a quality scope and it come with a 2" focuser.    I use 2" eyepieces exclusivly, panoptics, naglers and explore scientific.
                  So, perhaps I should consider another scope with a focus point more suitable to my eyepieces ?

                  Thanks, 
                  Twinklescope
                    
                  --- In William-Optics@yahoogroups.com, "Timm B" wrote:
                  >
                  > Hi Paul,
                  >
                  > The GTF102 that I have is similar in that it was optimized to be used for astrophotography so that the focuser wouldn't need a long extension for cameras.
                  >
                  > For visual use, you will probably need a 1.25" diagonal, any will do, but get a good dielectric like the WO one, and you will be happy. A 2" diagonal will push the eyepiece out much further in the optical path, and may not be able to reach focus.
                  >
                  > The trade off is that you will be able to easily reach focus with any camera. For your DSLR you will need a 2" photo adapter with the proper T-Ring attached. I like the one WO sells, but any other will work, which adds enough length to allow it to reach focus.
                  >
                  > I have the iEQ45 as well, and its my first GEM so its a bit of a learning curve for me, and with the long days right now I can really only get it out on weekends, and we haven't had many clear Fri or Sat night this summer. Look for the iOptron Yahoo groups and join them as well
                  >
                  > The binoviewer issue is related. Many refractors are too long to allow for the much longer optical path introduced by a binoviewer, so adding the barlow in front of it will sometimes help. The hitch is that you will definitely need that 1.25" diagonal, and even with that it still might not reach focus. I don't have a binoviewer, so I can't say for sure.
                  >
                  > If you need any help just let us know here, and we will try to help you as best we can.
                  >
                  > I'm almost done with a full review of the GTF102, and will post it here and on CloudyNights.com as soon as I can.
                  >
                  > Take care,
                  >
                  > Timm
                  >
                  >
                  >
                  > --- In William-Optics@yahoogroups.com, "pgabura" psg@ wrote:
                  > >
                  > >
                  > > My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10" Orion Dob for a few years and have a Celestron 6" SCT but this is my first purchase of a refractor. I want to get into astrophotography and was impressed with the sharp image and fast wide field performance of the WO short FL refractors.
                  > >
                  > > Based on research I decided to buy the GT81 to start on. I also have the FLT 132 on order and the iOptron iEQ45 mount.
                  > >
                  > > From reading other posts I have learned I should get the WO 2" tube for my T-ring and that Binoviewers are in general dificult to use on many telescopes. Perhaps these are the only answers available. Any additional insite would be greatly appreciated.
                  > >
                  > > Thanks
                  > >
                  > > Paul
                  > > --- In William-Optics@yahoogroups.com, "pgabura" wrote:
                  > > >
                  > > > I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.
                  > > >
                  > > > It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?
                  > > >
                  > > > The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.
                  > > >
                  > > > I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.
                  > > >
                  > > > I have tried it both with and without the WO 2" diagonal.
                  > > >
                  > > > Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
                  > > >
                  > >
                  >
                • Timm B
                  Hi Roger, Just to be clear, I have the GTF102 not the GTF81. I didn t have any issue reaching focus with the 2 eyepiece I have, using a 2 WO dielectric
                  Message 8 of 10 , Aug 12 12:29 PM
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                    Hi Roger,

                    Just to be clear, I have the GTF102 not the GTF81. I didn't have any issue reaching focus with the 2" eyepiece I have, using a 2" WO dielectric diagonal.

                    When using 1.25" eyepieces, and a 2" WO dielectric diagonal, the additional insert (2" to 1.25") is needed. This adds the extra length that might push some 1.25" eyepieces outside of the focus range. With 2" eyepieces you don't need the insert, but remember not all eyepieces focus at the same spot. Why? Because some eyepiece designs shift the focus point slightly due to the extra glass inside them.

                    Perhaps other here who have the GTF81 can comment on it for visual use, but it should be an excellent choice and has the added advantage of the flattener built in for sharp wide field views, and will be ready for taking astrophotos if you ever pursue that part of the hobby.

                    Timm

                    --- In William-Optics@yahoogroups.com, "twinklescope" <twinklescope@...> wrote:
                    >
                    > Hi Timm; I'm Roger and I'm new to the group. I'm just a visual
                    > observer not into AP yet. I was considering the GTF 81 because it
                    > seems like a quality scope and it come with a 2" focuser. I use 2"
                    > eyepieces exclusivly, panoptics, naglers and explore scientific.So,
                    > perhaps I should consider another scope with a focus point more suitable
                    > to my eyepieces ?
                    > Thanks, Twinklescope
                    > --- In William-Optics@yahoogroups.com, "Timm B" wrote:
                    > >
                    > > Hi Paul,
                    > >
                    > > The GTF102 that I have is similar in that it was optimized to be used
                    > for astrophotography so that the focuser wouldn't need a long extension
                    > for cameras.
                    > >
                    > > For visual use, you will probably need a 1.25" diagonal, any will do,
                    > but get a good dielectric like the WO one, and you will be happy. A 2"
                    > diagonal will push the eyepiece out much further in the optical path,
                    > and may not be able to reach focus.
                    > >
                    > > The trade off is that you will be able to easily reach focus with any
                    > camera. For your DSLR you will need a 2" photo adapter with the proper
                    > T-Ring attached. I like the one WO sells, but any other will work,
                    > which adds enough length to allow it to reach focus.
                    > >
                    > > I have the iEQ45 as well, and its my first GEM so its a bit of a
                    > learning curve for me, and with the long days right now I can really
                    > only get it out on weekends, and we haven't had many clear Fri or Sat
                    > night this summer. Look for the iOptron Yahoo groups and join them as
                    > well
                    > >
                    > > The binoviewer issue is related. Many refractors are too long to
                    > allow for the much longer optical path introduced by a binoviewer, so
                    > adding the barlow in front of it will sometimes help. The hitch is
                    > that you will definitely need that 1.25" diagonal, and even with that it
                    > still might not reach focus. I don't have a binoviewer, so I can't say
                    > for sure.
                    > >
                    > > If you need any help just let us know here, and we will try to help
                    > you as best we can.
                    > >
                    > > I'm almost done with a full review of the GTF102, and will post it
                    > here and on CloudyNights.com as soon as I can.
                    > >
                    > > Take care,
                    > >
                    > > Timm
                    > >
                    > >
                    > >
                    > > --- In William-Optics@yahoogroups.com, "pgabura" psg@ wrote:
                    > > >
                    > > >
                    > > > My appologies, I forgot to introduce myself. I am new to the group.
                    > I have been using a 10" Orion Dob for a few years and have a Celestron
                    > 6" SCT but this is my first purchase of a refractor. I want to get into
                    > astrophotography and was impressed with the sharp image and fast wide
                    > field performance of the WO short FL refractors.
                    > > >
                    > > > Based on research I decided to buy the GT81 to start on. I also have
                    > the FLT 132 on order and the iOptron iEQ45 mount.
                    > > >
                    > > > From reading other posts I have learned I should get the WO 2" tube
                    > for my T-ring and that Binoviewers are in general dificult to use on
                    > many telescopes. Perhaps these are the only answers available. Any
                    > additional insite would be greatly appreciated.
                    > > >
                    > > > Thanks
                    > > >
                    > > > Paul
                    > > > --- In William-Optics@yahoogroups.com, "pgabura" wrote:
                    > > > >
                    > > > > I was disapointed to find that the Televue Binoviewer, even with
                    > the special barlow lens that comes with the viewer, cannot reach focus
                    > with the GT81.
                    > > > >
                    > > > > It seems like an odd design of focuser as all of my eypieces seem
                    > to focus within about 1/4 of the focusers travel. I have used it with a
                    > Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would
                    > the remaining 3/4 of travel be used for?
                    > > > >
                    > > > > The only other eypiece I have had problems with is the Baader
                    > Planitarium 8-24 zoom lens which kind of reaches focus but only at
                    > maximum travel into the scope jammed up against the focuser body.
                    > > > >
                    > > > > I have also been unable to get focus on my Nikon D600 FX sensor
                    > DSLR. I have tried it with various lengths of 1.25" tubes with no luck.
                    > You can't crank the focuser in far enough.
                    > > > >
                    > > > > I have tried it both with and without the WO 2" diagonal.
                    > > > >
                    > > > > Am I doing something wrong? Have others had any difficulty
                    > obtaining focus with this telescope?
                    > > > >
                    > > >
                    > >
                    >
                  • Timm B
                    You re welcome Paul, Glad to help! Timm
                    Message 9 of 10 , Aug 12 12:29 PM
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                      You're welcome Paul,

                      Glad to help!

                      Timm

                      --- In William-Optics@yahoogroups.com, "pgabura" <psg@...> wrote:
                      >
                      >
                      >
                      > Timm
                      >
                      > Just wanted to report back and let you know that your advice was spot on. I purchased both items you recommended and was able to get focus with both the DSLR and the binoviewers.
                      >
                      > Thanks again for your help.
                      >
                      > Paul
                      >
                      >
                      > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
                      > >
                      > > Thanks for the reply Timm, your information was helpful. I have ordered both items and will give them a try.
                      > >
                      > > I will join the iOptron group as I am sure I am going to have questions.
                      > >
                      > > Paul
                      > >
                      > > --- In William-Optics@yahoogroups.com, "Timm B" <t.bottoni@> wrote:
                      > > >
                      > > > Hi Paul,
                      > > >
                      > > > The GTF102 that I have is similar in that it was optimized to be used for astrophotography so that the focuser wouldn't need a long extension for cameras.
                      > > >
                      > > > For visual use, you will probably need a 1.25" diagonal, any will do, but get a good dielectric like the WO one, and you will be happy. A 2" diagonal will push the eyepiece out much further in the optical path, and may not be able to reach focus.
                      > > >
                      > > > The trade off is that you will be able to easily reach focus with any camera. For your DSLR you will need a 2" photo adapter with the proper T-Ring attached. I like the one WO sells, but any other will work, which adds enough length to allow it to reach focus.
                      > > >
                      > > > I have the iEQ45 as well, and its my first GEM so its a bit of a learning curve for me, and with the long days right now I can really only get it out on weekends, and we haven't had many clear Fri or Sat night this summer. Look for the iOptron Yahoo groups and join them as well
                      > > >
                      > > > The binoviewer issue is related. Many refractors are too long to allow for the much longer optical path introduced by a binoviewer, so adding the barlow in front of it will sometimes help. The hitch is that you will definitely need that 1.25" diagonal, and even with that it still might not reach focus. I don't have a binoviewer, so I can't say for sure.
                      > > >
                      > > > If you need any help just let us know here, and we will try to help you as best we can.
                      > > >
                      > > > I'm almost done with a full review of the GTF102, and will post it here and on CloudyNights.com as soon as I can.
                      > > >
                      > > > Take care,
                      > > >
                      > > > Timm
                      > > >
                      > > >
                      > > >
                      > > > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
                      > > > >
                      > > > >
                      > > > > My appologies, I forgot to introduce myself. I am new to the group. I have been using a 10" Orion Dob for a few years and have a Celestron 6" SCT but this is my first purchase of a refractor. I want to get into astrophotography and was impressed with the sharp image and fast wide field performance of the WO short FL refractors.
                      > > > >
                      > > > > Based on research I decided to buy the GT81 to start on. I also have the FLT 132 on order and the iOptron iEQ45 mount.
                      > > > >
                      > > > > From reading other posts I have learned I should get the WO 2" tube for my T-ring and that Binoviewers are in general dificult to use on many telescopes. Perhaps these are the only answers available. Any additional insite would be greatly appreciated.
                      > > > >
                      > > > > Thanks
                      > > > >
                      > > > > Paul
                      > > > > --- In William-Optics@yahoogroups.com, "pgabura" <psg@> wrote:
                      > > > > >
                      > > > > > I was disapointed to find that the Televue Binoviewer, even with the special barlow lens that comes with the viewer, cannot reach focus with the GT81.
                      > > > > >
                      > > > > > It seems like an odd design of focuser as all of my eypieces seem to focus within about 1/4 of the focusers travel. I have used it with a Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would the remaining 3/4 of travel be used for?
                      > > > > >
                      > > > > > The only other eypiece I have had problems with is the Baader Planitarium 8-24 zoom lens which kind of reaches focus but only at maximum travel into the scope jammed up against the focuser body.
                      > > > > >
                      > > > > > I have also been unable to get focus on my Nikon D600 FX sensor DSLR. I have tried it with various lengths of 1.25" tubes with no luck. You can't crank the focuser in far enough.
                      > > > > >
                      > > > > > I have tried it both with and without the WO 2" diagonal.
                      > > > > >
                      > > > > > Am I doing something wrong? Have others had any difficulty obtaining focus with this telescope?
                      > > > > >
                      > > > >
                      > > >
                      > >
                      >
                    • twinklescope
                      Hi Again Timm; Thank you for your helpful thoughts on the 2 eyepiece question. I really took a long look at the 102 as well, it looks like a great scope.
                      Message 10 of 10 , Aug 12 2:51 PM
                      • 0 Attachment
                        Hi Again Timm;

                        Thank you for your helpful thoughts on the 2" eyepiece question. I really took a long look at the 102 as well, it looks like a great scope. However, I would be using the 81mm for a visual "grab n'go" and also as a finder on my 16" DOB.
                        So, I will be looking for as much FOV as possible and the F/5.9 of the 81mm perhaps seems a better fit than the 102mm at F/6.9. Also, weight is a balance concern and the 102 is 3 pounds heaver.

                        Clear Skies,
                        Roger

                        --- In William-Optics@yahoogroups.com, "Timm B" <t.bottoni@...> wrote:
                        >
                        > Hi Roger,
                        >
                        > Just to be clear, I have the GTF102 not the GTF81. I didn't have any issue reaching focus with the 2" eyepiece I have, using a 2" WO dielectric diagonal.
                        >
                        > When using 1.25" eyepieces, and a 2" WO dielectric diagonal, the additional insert (2" to 1.25") is needed. This adds the extra length that might push some 1.25" eyepieces outside of the focus range. With 2" eyepieces you don't need the insert, but remember not all eyepieces focus at the same spot. Why? Because some eyepiece designs shift the focus point slightly due to the extra glass inside them.
                        >
                        > Perhaps other here who have the GTF81 can comment on it for visual use, but it should be an excellent choice and has the added advantage of the flattener built in for sharp wide field views, and will be ready for taking astrophotos if you ever pursue that part of the hobby.
                        >
                        > Timm
                        >
                        > --- In William-Optics@yahoogroups.com, "twinklescope" <twinklescope@> wrote:
                        > >
                        > > Hi Timm; I'm Roger and I'm new to the group. I'm just a visual
                        > > observer not into AP yet. I was considering the GTF 81 because it
                        > > seems like a quality scope and it come with a 2" focuser. I use 2"
                        > > eyepieces exclusivly, panoptics, naglers and explore scientific.So,
                        > > perhaps I should consider another scope with a focus point more suitable
                        > > to my eyepieces ?
                        > > Thanks, Twinklescope
                        > > --- In William-Optics@yahoogroups.com, "Timm B" wrote:
                        > > >
                        > > > Hi Paul,
                        > > >
                        > > > The GTF102 that I have is similar in that it was optimized to be used
                        > > for astrophotography so that the focuser wouldn't need a long extension
                        > > for cameras.
                        > > >
                        > > > For visual use, you will probably need a 1.25" diagonal, any will do,
                        > > but get a good dielectric like the WO one, and you will be happy. A 2"
                        > > diagonal will push the eyepiece out much further in the optical path,
                        > > and may not be able to reach focus.
                        > > >
                        > > > The trade off is that you will be able to easily reach focus with any
                        > > camera. For your DSLR you will need a 2" photo adapter with the proper
                        > > T-Ring attached. I like the one WO sells, but any other will work,
                        > > which adds enough length to allow it to reach focus.
                        > > >
                        > > > I have the iEQ45 as well, and its my first GEM so its a bit of a
                        > > learning curve for me, and with the long days right now I can really
                        > > only get it out on weekends, and we haven't had many clear Fri or Sat
                        > > night this summer. Look for the iOptron Yahoo groups and join them as
                        > > well
                        > > >
                        > > > The binoviewer issue is related. Many refractors are too long to
                        > > allow for the much longer optical path introduced by a binoviewer, so
                        > > adding the barlow in front of it will sometimes help. The hitch is
                        > > that you will definitely need that 1.25" diagonal, and even with that it
                        > > still might not reach focus. I don't have a binoviewer, so I can't say
                        > > for sure.
                        > > >
                        > > > If you need any help just let us know here, and we will try to help
                        > > you as best we can.
                        > > >
                        > > > I'm almost done with a full review of the GTF102, and will post it
                        > > here and on CloudyNights.com as soon as I can.
                        > > >
                        > > > Take care,
                        > > >
                        > > > Timm
                        > > >
                        > > >
                        > > >
                        > > > --- In William-Optics@yahoogroups.com, "pgabura" psg@ wrote:
                        > > > >
                        > > > >
                        > > > > My appologies, I forgot to introduce myself. I am new to the group.
                        > > I have been using a 10" Orion Dob for a few years and have a Celestron
                        > > 6" SCT but this is my first purchase of a refractor. I want to get into
                        > > astrophotography and was impressed with the sharp image and fast wide
                        > > field performance of the WO short FL refractors.
                        > > > >
                        > > > > Based on research I decided to buy the GT81 to start on. I also have
                        > > the FLT 132 on order and the iOptron iEQ45 mount.
                        > > > >
                        > > > > From reading other posts I have learned I should get the WO 2" tube
                        > > for my T-ring and that Binoviewers are in general dificult to use on
                        > > many telescopes. Perhaps these are the only answers available. Any
                        > > additional insite would be greatly appreciated.
                        > > > >
                        > > > > Thanks
                        > > > >
                        > > > > Paul
                        > > > > --- In William-Optics@yahoogroups.com, "pgabura" wrote:
                        > > > > >
                        > > > > > I was disapointed to find that the Televue Binoviewer, even with
                        > > the special barlow lens that comes with the viewer, cannot reach focus
                        > > with the GT81.
                        > > > > >
                        > > > > > It seems like an odd design of focuser as all of my eypieces seem
                        > > to focus within about 1/4 of the focusers travel. I have used it with a
                        > > Televue Panoptics 27mm and Explore Scientific 15mm and 6.7mm. What would
                        > > the remaining 3/4 of travel be used for?
                        > > > > >
                        > > > > > The only other eypiece I have had problems with is the Baader
                        > > Planitarium 8-24 zoom lens which kind of reaches focus but only at
                        > > maximum travel into the scope jammed up against the focuser body.
                        > > > > >
                        > > > > > I have also been unable to get focus on my Nikon D600 FX sensor
                        > > DSLR. I have tried it with various lengths of 1.25" tubes with no luck.
                        > > You can't crank the focuser in far enough.
                        > > > > >
                        > > > > > I have tried it both with and without the WO 2" diagonal.
                        > > > > >
                        > > > > > Am I doing something wrong? Have others had any difficulty
                        > > obtaining focus with this telescope?
                        > > > > >
                        > > > >
                        > > >
                        > >
                        >
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