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Re: APO110FL

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  • Yuri
    ... Dear Pop, the test plate are our test instruments during spherical lens fabrication. The test based on interference of light* between test plate and
    Message 1 of 26 , Aug 1 6:00 PM
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      --- In tec-scopes@yahoogroups.com, "popkrab" <popkrab@...> wrote:
      >
      > Thank you very much Yuri. I didn't order that but feel excited that.
      >
      > If possible, can you explain why it needs to use test plates.
      >
      > Best Regards,
      > POP

      Dear Pop,
      the test plate are our test instruments during spherical lens fabrication.
      The test based on interference of light* between test plate and working surface of the objective lens of opposite curvature. *Knowing also as Newton's ring.

      The test plates made with curvatures according to objective design, in case of oiled triplet design we have 6 radii to test, but since R2=R3 and R4=R5, only 4 sets of test plates are needed.

      During manufacturing optician tests surface in question against test plate surface of opposite curvature by placing test plate on the cleaned lens surface and by counting number of visible Newton's rings can conclude how far surface in question from perfect.
      As well this test shows irregularity on lens surfaces such as astigmatism, turned edge, etc. The only hidden from this type of test is internal quality of the lens glass, that is tested when all thee lenses completed and assembled as an objective.

      We have relatively large "library" of the test plates that were done for many projects, but in most cases every new telescope requires new test plates.

      Best regards, Yuri
    • Teri Smoot
      Gee whiz, I wonder why you are doing these test plates since: Hi Teri, have we ever promised anything in this size APO? Big (-: back! Teri ... From:
      Message 2 of 26 , Aug 1 6:26 PM
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        Gee whiz, I wonder why you are doing these test plates since:    "Hi Teri, have we ever promised anything in this size APO?"
        Big (-:    back!
         
        Teri 
        ----- Original Message -----
        From: Yuri
        Sent: Saturday, August 01, 2009 6:00 PM
        Subject: [tec-scopes] Re: APO110FL

         

        --- In tec-scopes@yahoogro ups.com, "popkrab" <popkrab@... > wrote:
        >
        > Thank you very much Yuri. I didn't order that but feel excited that.
        >
        > If possible, can you explain why it needs to use test plates.
        >
        > Best Regards,
        > POP

        Dear Pop,
        the test plate are our test instruments during spherical lens fabrication.
        The test based on interference of light* between test plate and working surface of the objective lens of opposite curvature. *Knowing also as Newton's ring.

        The test plates made with curvatures according to objective design, in case of oiled triplet design we have 6 radii to test, but since R2=R3 and R4=R5, only 4 sets of test plates are needed.

        During manufacturing optician tests surface in question against test plate surface of opposite curvature by placing test plate on the cleaned lens surface and by counting number of visible Newton's rings can conclude how far surface in question from perfect.
        As well this test shows irregularity on lens surfaces such as astigmatism, turned edge, etc. The only hidden from this type of test is internal quality of the lens glass, that is tested when all thee lenses completed and assembled as an objective.

        We have relatively large "library" of the test plates that were done for many projects, but in most cases every new telescope requires new test plates.

        Best regards, Yuri

      • popkrab
        Dear Yuri, Thank you very much for your extensive explanation. I m very appreciate your help. Best Regards, Pornchai POP
        Message 3 of 26 , Aug 1 9:36 PM
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          Dear Yuri,

          Thank you very much for your extensive explanation. I'm very appreciate your help.

          Best Regards,
          Pornchai POP

          --- In tec-scopes@yahoogroups.com, "Yuri" <tec@...> wrote:
          >
          > --- In tec-scopes@yahoogroups.com, "popkrab" <popkrab@> wrote:
          > >
          > > Thank you very much Yuri. I didn't order that but feel excited that.
          > >
          > > If possible, can you explain why it needs to use test plates.
          > >
          > > Best Regards,
          > > POP
          >
          > Dear Pop,
          > the test plate are our test instruments during spherical lens fabrication.
          > The test based on interference of light* between test plate and working surface of the objective lens of opposite curvature. *Knowing also as Newton's ring.
          >
          > The test plates made with curvatures according to objective design, in case of oiled triplet design we have 6 radii to test, but since R2=R3 and R4=R5, only 4 sets of test plates are needed.
          >
          > During manufacturing optician tests surface in question against test plate surface of opposite curvature by placing test plate on the cleaned lens surface and by counting number of visible Newton's rings can conclude how far surface in question from perfect.
          > As well this test shows irregularity on lens surfaces such as astigmatism, turned edge, etc. The only hidden from this type of test is internal quality of the lens glass, that is tested when all thee lenses completed and assembled as an objective.
          >
          > We have relatively large "library" of the test plates that were done for many projects, but in most cases every new telescope requires new test plates.
          >
          > Best regards, Yuri
          >
        • vahe352
          ... Yuri, I need more education here; It is true that R2=R3, but one lens surface is concave and the other is convex, I am trying to understand how a single
          Message 4 of 26 , Aug 2 10:12 AM
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            > The test plates made with curvatures according to objective design, in case of oiled triplet design we have 6 radii to test, but since R2=R3 and R4=R5, only 4 sets of test plates are needed.>

            Yuri, I need more education here;

            It is true that R2=R3, but one lens surface is concave and the other is convex, I am trying to understand how a single test plate can be used on both of these surfaces.

            Vahe
          • Yuri
            ... Dear Vahe, the test plates made as a set concave and covex - as you may see on group main page picture there are 4 sets. The test plates in most case made
            Message 5 of 26 , Aug 2 12:06 PM
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              --- In tec-scopes@yahoogroups.com, "vahe352" <vahesahakian@...> wrote:
              >
              > > The test plates made with curvatures according to objective design, in case of oiled triplet design we have 6 radii to test, but since R2=R3 and R4=R5, only 4 sets of test plates are needed.>
              >
              > Yuri, I need more education here;
              >
              > It is true that R2=R3, but one lens surface is concave and the other is convex, I am trying to understand how a single test plate can be used on both of these surfaces.
              >
              > Vahe
              >
              Dear Vahe,
              the test plates made as a set concave and covex - as you may see on group main page picture there are 4 sets.
              The test plates in most case made as a set of opposite curvatures and they are test agaist each other during manufacturing.
              So one plate for testing R2, opposite one for R3, etc.
              Regards, Yuri
            • Paul Leuba
              ... Yuri, Does TEC manufacturer the test plates in house? What do you test the reference test plates against to ensure they are as perfect as can be? In
              Message 6 of 26 , Aug 2 4:42 PM
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                > We have relatively large "library" of the test plates that were done
                > for many projects, but in most cases every new telescope requires
                > new test plates.


                Yuri,

                Does TEC manufacturer the test plates in house? What do you test
                the reference test plates against to ensure they are as perfect as
                can be? In other words how do you make sure that the test plates
                are good? Is this done via interferometer? I have often
                wondered how test plates are manufactured and then tested so as to
                be "known good".

                Looking forward to receiving my APO160FL.

                Very Best Regards.

                --


                Paul Leuba
                New Freedom, PA
              • Yuri
                ... Yes Paul, we do them in house. The radius of curvature of both test plates is tested with very precision spherometer. And in the end plates tested against
                Message 7 of 26 , Aug 2 6:24 PM
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                  --- In tec-scopes@yahoogroups.com, Paul Leuba <peleuba@...> wrote:
                  >
                  > > We have relatively large "library" of the test plates that were done
                  > > for many projects, but in most cases every new telescope requires
                  > > new test plates.
                  >
                  >
                  > Yuri,
                  >
                  > Does TEC manufacturer the test plates in house? What do you test
                  > the reference test plates against to ensure they are as perfect as
                  > can be? In other words how do you make sure that the test plates
                  > are good? Is this done via interferometer? I have often
                  > wondered how test plates are manufactured and then tested so as to
                  > be "known good".
                  > Looking forward to receiving my APO160FL.
                  >
                  > Very Best Regards.
                  > Paul Leuba
                  > New Freedom, PA
                  >
                  Yes Paul, we do them in house.
                  The radius of curvature of both test plates is tested with very precision spherometer.
                  And in the end plates tested against each other, if both plates are spherical and has same curvature you may see neither uniform illumination or parallel lines if curvatures are slightly different for amount of only 2-3 wave lengths.
                  Regards, Yuri
                • Tim Khan
                  Yuir, how are the mechanics coming along (focuser/Tube)? Tim ... From: Yuri To: tec-scopes@yahoogroups.com Sent: Sunday, August
                  Message 8 of 26 , Aug 3 5:31 AM
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                    Yuir, how are the mechanics coming along (focuser/Tube)?

                    Tim


                    ----- Original Message ----
                    From: Yuri <tec@...>
                    To: tec-scopes@yahoogroups.com
                    Sent: Sunday, August 2, 2009 9:24:56 PM
                    Subject: [tec-scopes] Re: APO110FL

                    --- In tec-scopes@yahoogroups.com, Paul Leuba <peleuba@...> wrote:
                    >
                    > > We have relatively large "library" of the test plates that were done
                    >  > for many projects, but in most cases every new telescope requires
                    >  > new test plates.
                    >
                    >
                    > Yuri,
                    >
                    > Does TEC manufacturer the test plates in house?  What do you test
                    > the reference test plates against to ensure they are as perfect as
                    > can be?  In other words how do you make sure that the test plates
                    > are good?  Is this done via interferometer?  I have often
                    > wondered how test plates are manufactured and then tested so as to
                    > be "known good".
                    > Looking forward to receiving my APO160FL.
                    >
                    > Very Best Regards.
                    > Paul Leuba
                    > New Freedom, PA
                    >
                    Yes Paul, we do them in house.
                    The radius of curvature of both test plates is tested with very precision spherometer.
                    And in the end plates tested against each other, if both plates are spherical and has same curvature you may see neither uniform illumination or parallel lines if curvatures are slightly different for amount of only 2-3 wave lengths.
                    Regards, Yuri



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

                    Yahoo! Groups Links
                  • rsampsonus
                    Hi Yuri, What type of glass are you using for the Optical Test Plates? Something along the lines of a BK7? (Ohara S-BSL7 or Schott NBK-7)? Best Regards, Ron
                    Message 9 of 26 , Aug 3 1:30 PM
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                      Hi Yuri,


                      What type of glass are you using for the Optical Test Plates? Something along the lines of a BK7? (Ohara S-BSL7 or Schott NBK-7)?



                      Best Regards, Ron






                      --- In tec-scopes@yahoogroups.com, "Yuri" <tec@...> wrote:
                      >
                      > --- In tec-scopes@yahoogroups.com, "popkrab" <popkrab@> wrote:
                      > >
                      > > Thank you very much Yuri. I didn't order that but feel excited that.
                      > >
                      > > If possible, can you explain why it needs to use test plates.
                      > >
                      > > Best Regards,
                      > > POP
                      >
                      > Dear Pop,
                      > the test plate are our test instruments during spherical lens fabrication.
                      > The test based on interference of light* between test plate and working surface of the objective lens of opposite curvature. *Knowing also as Newton's ring.
                      >
                      > The test plates made with curvatures according to objective design, in case of oiled triplet design we have 6 radii to test, but since R2=R3 and R4=R5, only 4 sets of test plates are needed.
                      >
                      > During manufacturing optician tests surface in question against test plate surface of opposite curvature by placing test plate on the cleaned lens surface and by counting number of visible Newton's rings can conclude how far surface in question from perfect.
                      > As well this test shows irregularity on lens surfaces such as astigmatism, turned edge, etc. The only hidden from this type of test is internal quality of the lens glass, that is tested when all thee lenses completed and assembled as an objective.
                      >
                      > We have relatively large "library" of the test plates that were done for many projects, but in most cases every new telescope requires new test plates.
                      >
                      > Best regards, Yuri
                      >
                    • Paul Leuba
                      ... Yuri, Thank you very much for willingness to answer questions about your manufacturing processes. -- Paul Leuba New Freedom, PA
                      Message 10 of 26 , Aug 3 2:27 PM
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                        > Yes Paul, we do them in house.

                        Yuri,

                        Thank you very much for willingness to answer questions about your
                        manufacturing processes.


                        --


                        Paul Leuba
                        New Freedom, PA
                      • Yuri
                        ... Hi Yuri, ... Ron, BK7 or similar crowns have relatively high CTE and it would take a lot of time to wait for test plate to get original shape after
                        Message 11 of 26 , Aug 3 3:31 PM
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                          --- In tec-scopes@yahoogroups.com, "rsampsonus" <rsampsonus@...> wrote:
                          Hi Yuri,

                          > What type of glass are you using for the Optical Test Plates? Something along the lines of a BK7? (Ohara S-BSL7 or Schott NBK-7)?
                          > Best Regards, Ron
                          >

                          Ron,
                          BK7 or similar crowns have relatively high CTE and it would take a lot of time to wait for test plate to get original shape after opticians hands (!).
                          In most cases we are using Pyrex or similar substrates and sometimes Quartz.
                          Regards, Yuri
                        • Yuri
                          ... Tim, most of the parts for OTA are coming fine - they are pretty similar to larger scopes parts; focuser project is quite different and take a lot of time
                          Message 12 of 26 , Aug 3 3:35 PM
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                            --- In tec-scopes@yahoogroups.com, Tim Khan <timkhan@...> wrote:
                            >
                            > Yuir, how are the mechanics coming along (focuser/Tube)?
                            >
                            > Tim
                            >
                            Tim, most of the parts for OTA are coming fine - they are pretty similar to larger scopes parts; focuser project is quite different and take a lot of time for testing checking all components of it...
                            Best regards,
                            Yuri
                          • rsampsonus
                            Hi Yuri, I see, you are chosing the pyrex or quartz materials on the Test Plates to be somewhat stable and come to equilibrium quicker of the final figure to
                            Message 13 of 26 , Aug 4 8:53 AM
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                              Hi Yuri,

                              I see, you are chosing the pyrex or quartz materials on the Test Plates to be somewhat stable and come to equilibrium quicker of the final figure to minimize inspection times in figuring a lens. Also seeing the Test Plate being rather thick, there is a large thermal mass there and outside temporary interaction (body heat, etc.) would have less impact on the Test Plate changing figure quickly?
                              In a lens assembly design I guess one could surmise the optical properties of the BK-7 glass would out weigh the disadvantage of the high CTE in the design and chose similar mating glass with similar properties? This would certainly impact lens cell design!




                              Thanks for the insight Yuri!, Best Regards Ron





                              --- In tec-scopes@yahoogroups.com, "Yuri" <tec@...> wrote:
                              >
                              > --- In tec-scopes@yahoogroups.com, "rsampsonus" <rsampsonus@> wrote:
                              > Hi Yuri,
                              >
                              > > What type of glass are you using for the Optical Test Plates? Something along the lines of a BK7? (Ohara S-BSL7 or Schott NBK-7)?
                              > > Best Regards, Ron
                              > >
                              >
                              > Ron,
                              > BK7 or similar crowns have relatively high CTE and it would take a lot of time to wait for test plate to get original shape after opticians hands (!).
                              > In most cases we are using Pyrex or similar substrates and sometimes Quartz.
                              > Regards, Yuri
                              >
                            • Chris Lord
                              Yuri, No doubt this question has been asked many times, but what is needed to fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus to be
                              Message 14 of 26 , Sep 1, 2009
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                                Yuri,

                                No doubt this question has been asked many times, but what is needed to
                                fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus
                                to be reached using a DSLR (Sony alpha 900 in my case) and a WO 2-inch
                                Sony Photo Adapter?

                                Chris Lord
                              • Chris Lord
                                Yuri, No doubt this question has been asked many times, but what is needed to fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus to be
                                Message 15 of 26 , Sep 2, 2009
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                                  Yuri,

                                  No doubt this question has been asked many times, but what is needed to
                                  fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus
                                  to be reached using a DSLR (Sony alpha 900 in my case) and a WO 2-inch
                                  Sony Photo Adapter?

                                  Chris Lord
                                • yuri80226
                                  ... Chris, I am really not familiar with TCF or DSLR, sorry. But the key thing to any set up is the back focus distance which is ~7 for most of our scopes...
                                  Message 16 of 26 , Sep 2, 2009
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                                    --- In tec-scopes@yahoogroups.com, Chris Lord <chrislord@...> wrote:
                                    >
                                    > Yuri,
                                    >
                                    > No doubt this question has been asked many times, but what is needed to
                                    > fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus
                                    > to be reached using a DSLR (Sony alpha 900 in my case) and a WO 2-inch
                                    > Sony Photo Adapter?
                                    >
                                    > Chris Lord
                                    >
                                    Chris, I am really not familiar with TCF or DSLR, sorry.
                                    But the key thing to any set up is the back focus distance which is ~7" for most of our scopes... just summarize light pass distances of your equipment and check if it is nt longer than the BF.
                                    Regards,
                                    Yuri

                                    If I would have more money and main thing - time I would finish my own development for digital focuser...
                                  • Chris Lord
                                    Yuri, The TCF-S has an optical path distance of 4.5-inches & drawtube travel 0.6-inches, & with the digital read out centralised, this adds up to 4.5 + 0.3 =
                                    Message 17 of 26 , Sep 3, 2009
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                                      Yuri,

                                      The TCF-S has an optical path distance of 4.5-inches & drawtube travel
                                      0.6-inches, & with the digital read out centralised, this adds up to
                                      4.5 + 0.3 = 4.8-inches. My Sony a900 DSLR and WO 2-inch adapter sleeve
                                      has an opd 4-inches. Total opd 8.8-inches.

                                      This is with a 2-inch male adapter screwed into the TCF-S focuser base

                                      Removing the 2-inch collet off the FTF3545 racktube reduces the opd by
                                      ~ 2-inches, which in theory places the opd (6.8-inches) within the
                                      available backfocus. But Neither Feathertouch nor Optec make an adapter
                                      that connects the TCF-S base directly within the FTF3545's racktube.

                                      I don't want to replace the FTF3454's pinion with a motorised version,
                                      I want to connect the TCF-S onto the back of it, and still have some
                                      opd left without having to resort to a focal extender.

                                      Before I go to the time and trouble of designing and machining one for
                                      myself, I need to establish that it hasn't already been done.

                                      So is there anyone on this list who has successfully fitted a standard
                                      TCF-S focuser onto the TEC140APO for use with a DSLR in either the
                                      Canon, Nikon or Sony range (APS-C or Fx format)?

                                      Chris Lord

                                      On Sep 03, 2009, at 04:39, yuri80226 wrote:

                                      > --- In tec-scopes@yahoogroups.com, Chris Lord <chrislord@...> wrote:
                                      > >
                                      > > Yuri,
                                      > >
                                      > > No doubt this question has been asked many times, but what is
                                      > needed to
                                      > > fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime
                                      > focus
                                      > > to be reached using a DSLR (Sony alpha 900 in my case) and a WO
                                      > 2-inch
                                      > > Sony Photo Adapter?
                                      > >
                                      > > Chris Lord
                                      > >
                                      > Chris, I am really not familiar with TCF or DSLR, sorry.
                                      > But the key thing to any set up is the back focus distance which is
                                      > ~7" for most of our scopes... just summarize light pass distances of
                                      > your equipment and check if it is nt longer than the BF.
                                      > Regards,
                                      > Yuri
                                      >
                                      > If I would have more money and main thing - time I would finish my
                                      > own development for digital focuser...
                                    • Tim Khan
                                      Chris, How about a using a PDF from FLI. Total thickness is about 1 to 1.38 (3/8 travel). Tim ... From: Chris Lord To:
                                      Message 18 of 26 , Sep 3, 2009
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                                        Chris,

                                        How about a using a PDF from FLI. Total thickness is about 1" to 1.38" (3/8" travel).

                                        Tim


                                        ----- Original Message ----
                                        From: Chris Lord <chrislord@...>
                                        To: tec-scopes@yahoogroups.com
                                        Sent: Thursday, September 3, 2009 4:47:41 AM
                                        Subject: Re: [tec-scopes] Re: TCF-S on TEC140APO

                                        Yuri,

                                        The TCF-S has an optical path distance of 4.5-inches & drawtube travel 0.6-inches, & with the digital read out centralised, this adds up to 4.5 + 0.3 = 4.8-inches. My Sony a900 DSLR and WO 2-inch adapter sleeve has an opd 4-inches. Total opd 8.8-inches.

                                        This is with a 2-inch male adapter screwed into the TCF-S focuser base

                                        Removing the 2-inch collet off the FTF3545 racktube reduces the opd by ~ 2-inches, which in theory places the opd (6.8-inches) within the available backfocus. But Neither Feathertouch nor Optec make an adapter that connects the TCF-S base directly within the FTF3545's racktube.

                                        I don't want to replace the FTF3454's pinion with a motorised version, I want to connect the TCF-S onto the back of it, and still have some opd left without having to resort to a focal extender.

                                        Before I go to the time and trouble of designing and machining one for myself, I need to establish that it hasn't already been done.

                                        So is there anyone on this list who has successfully fitted a standard TCF-S focuser onto the TEC140APO for use with a DSLR in either the Canon, Nikon or Sony range (APS-C or Fx format)?

                                        Chris Lord

                                        On Sep 03, 2009, at 04:39, yuri80226 wrote:

                                        > --- In tec-scopes@yahoogroups.com, Chris Lord <chrislord@...> wrote:
                                        >  >
                                        >  > Yuri,
                                        >  >
                                        >  > No doubt this question has been asked many times, but what is needed to
                                        >  > fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus
                                        >  > to be reached using a DSLR (Sony alpha 900 in my case) and a WO 2-inch
                                        >  > Sony Photo Adapter?
                                        >  >
                                        >  > Chris Lord
                                        >  >
                                        >  Chris, I am really not familiar with TCF or DSLR, sorry.
                                        >  But the key thing to any set up is the back focus distance which is ~7" for most of our scopes... just summarize light pass distances of your equipment and check if it is nt longer than the BF.
                                        >  Regards,
                                        >  Yuri
                                        >
                                        >  If I would have more money and main thing - time I would finish my own development for digital focuser...
                                      • Chris Lord
                                        If I were starting afresh it would be a viable option. I ve been adapter juggling, and think I ve come up with a working combination: Sony T adapter and 2-inch
                                        Message 19 of 26 , Sep 3, 2009
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                                          If I were starting afresh it would be a viable option. I've been
                                          adapter juggling, and think I've come up with a working combination:

                                          Sony T adapter and 2-inch sleeve - with DSLR opd 2.25-inches
                                          2-inch sleeve adapter on TCF-S - combined opd 4.5-inches

                                          this gives me ~ 0.25-inch residual back focus to play with.

                                          So I'll give it a try and see if it works. Once our monsoon season ends
                                          that is!

                                          Chris Lord

                                          On Sep 03, 2009, at 12:10, Tim Khan wrote:

                                          > Chris,
                                          >
                                          > How about a using a PDF from FLI. Total thickness is about 1" to
                                          > 1.38" (3/8" travel).
                                          >
                                          > Tim
                                          >
                                          > ----- Original Message ----
                                          > From: Chris Lord <chrislord@...>
                                          > To: tec-scopes@yahoogroups.com
                                          > Sent: Thursday, September 3, 2009 4:47:41 AM
                                          > Subject: Re: [tec-scopes] Re: TCF-S on TEC140APO
                                          >
                                          > Yuri,
                                          >
                                          > The TCF-S has an optical path distance of 4.5-inches & drawtube
                                          > travel 0.6-inches, & with the digital read out centralised, this adds
                                          > up to 4.5 + 0.3 = 4.8-inches. My Sony a900 DSLR and WO 2-inch adapter
                                          > sleeve has an opd 4-inches. Total opd 8.8-inches.
                                          >
                                          > This is with a 2-inch male adapter screwed into the TCF-S focuser base
                                          >
                                          > Removing the 2-inch collet off the FTF3545 racktube reduces the opd
                                          > by ~ 2-inches, which in theory places the opd (6.8-inches) within the
                                          > available backfocus. But Neither Feathertouch nor Optec make an
                                          > adapter that connects the TCF-S base directly within the FTF3545's
                                          > racktube.
                                          >
                                          > I don't want to replace the FTF3454's pinion with a motorised
                                          > version, I want to connect the TCF-S onto the back of it, and still
                                          > have some opd left without having to resort to a focal extender.
                                          >
                                          > Before I go to the time and trouble of designing and machining one
                                          > for myself, I need to establish that it hasn't already been done.
                                          >
                                          > So is there anyone on this list who has successfully fitted a
                                          > standard TCF-S focuser onto the TEC140APO for use with a DSLR in
                                          > either the Canon, Nikon or Sony range (APS-C or Fx format)?
                                          >
                                          > Chris Lord
                                          >
                                          > On Sep 03, 2009, at 04:39, yuri80226 wrote:
                                          >
                                          > > --- In tec-scopes@yahoogroups.com, Chris Lord <chrislord@...> wrote:
                                          > >  >
                                          > >  > Yuri,
                                          > >  >
                                          > >  > No doubt this question has been asked many times, but what is
                                          > needed to
                                          > >  > fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable
                                          > prime focus
                                          > >  > to be reached using a DSLR (Sony alpha 900 in my case) and a WO
                                          > 2-inch
                                          > >  > Sony Photo Adapter?
                                          > >  >
                                          > >  > Chris Lord
                                          > >  >
                                          > >  Chris, I am really not familiar with TCF or DSLR, sorry.
                                          > >  But the key thing to any set up is the back focus distance which
                                          > is ~7" for most of our scopes... just summarize light pass distances
                                          > of your equipment and check if it is nt longer than the BF.
                                          > >  Regards,
                                          > >  Yuri
                                          > >
                                          > >  If I would have more money and main thing - time I would finish my
                                          > own development for digital focuser...
                                          >
                                          >
                                        • Tim Khan
                                          I understand, however you can always sell the the TCF-S to get a PDF. Hopefully your adapters will work accordingly. Another way is what my friend does on
                                          Message 20 of 26 , Sep 3, 2009
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                                            I understand, however you can always sell the the TCF-S to get a PDF.

                                            Hopefully your adapters will work accordingly. Another way is what my friend does on his 140. He has the robofocus on the left and the FT knobs on the right and he just loosens the collar for visual.



                                            ----- Original Message ----
                                            From: Chris Lord <chrislord@...>
                                            To: tec-scopes@yahoogroups.com
                                            Sent: Thursday, September 3, 2009 7:45:46 AM
                                            Subject: Re: [tec-scopes] Re: TCF-S on TEC140APO

                                            If I were starting afresh it would be a viable option. I've been adapter juggling, and think I've come up with a working combination:

                                            Sony T adapter and 2-inch sleeve - with DSLR opd 2.25-inches
                                            2-inch sleeve adapter on TCF-S - combined opd 4.5-inches

                                            this gives me ~ 0.25-inch residual back focus to play with.

                                            So I'll give it a try and see if it works. Once our monsoon season ends that is!

                                            Chris Lord

                                            On Sep 03, 2009, at 12:10, Tim Khan wrote:

                                            > Chris,
                                            >
                                            >  How about a using a PDF from FLI. Total thickness is about 1" to 1.38" (3/8" travel).
                                            >
                                            >  Tim
                                            >
                                            >  ----- Original Message ----
                                            >  From: Chris Lord <chrislord@...>
                                            >  To: tec-scopes@yahoogroups.com
                                            >  Sent: Thursday, September 3, 2009 4:47:41 AM
                                            >  Subject: Re: [tec-scopes] Re: TCF-S on TEC140APO
                                            >
                                            >  Yuri,
                                            >
                                            >  The TCF-S has an optical path distance of 4.5-inches & drawtube travel 0.6-inches, & with the digital read out centralised, this adds up to 4.5 + 0.3 = 4.8-inches. My Sony a900 DSLR and WO 2-inch adapter sleeve has an opd 4-inches. Total opd 8.8-inches.
                                            >
                                            >  This is with a 2-inch male adapter screwed into the TCF-S focuser base
                                            >
                                            >  Removing the 2-inch collet off the FTF3545 racktube reduces the opd by ~ 2-inches, which in theory places the opd (6.8-inches) within the available backfocus. But Neither Feathertouch nor Optec make an adapter that connects the TCF-S base directly within the FTF3545's racktube.
                                            >
                                            >  I don't want to replace the FTF3454's pinion with a motorised version, I want to connect the TCF-S onto the back of it, and still have some opd left without having to resort to a focal extender.
                                            >
                                            >  Before I go to the time and trouble of designing and machining one for myself, I need to establish that it hasn't already been done.
                                            >
                                            >  So is there anyone on this list who has successfully fitted a standard TCF-S focuser onto the TEC140APO for use with a DSLR in either the Canon, Nikon or Sony range (APS-C or Fx format)?
                                            >
                                            >  Chris Lord
                                            >
                                            >  On Sep 03, 2009, at 04:39, yuri80226 wrote:
                                            >
                                            >  > --- In tec-scopes@yahoogroups.com, Chris Lord <chrislord@...> wrote:
                                            >  >  >
                                            >  >  > Yuri,
                                            >  >  >
                                            >  >  > No doubt this question has been asked many times, but what is needed to
                                            >  >  > fit a TCF-S 2-inch focuser to my TEC140APO, so as to enable prime focus
                                            >  >  > to be reached using a DSLR (Sony alpha 900 in my case) and a WO 2-inch
                                            >  >  > Sony Photo Adapter?
                                            >  >  >
                                            >  >  > Chris Lord
                                            >  >  >
                                            >  >  Chris, I am really not familiar with TCF or DSLR, sorry.
                                            >  >  But the key thing to any set up is the back focus distance which is ~7" for most of our scopes... just summarize light pass distances of your equipment and check if it is nt longer than the BF.
                                            >  >  Regards,
                                            >  >  Yuri
                                            >  >
                                            >  >  If I would have more money and main thing - time I would finish my own development for digital focuser...
                                            >
                                            >
                                          • Chris Lord
                                            No need, according to my drawing when the TCF-S is connected to the FTF3545 via a 2-inch nosepiece there is 0 .97 ± 0 .38 remaining backfocus with a Sony a900
                                            Message 21 of 26 , Sep 3, 2009
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                                              No need, according to my drawing when the TCF-S is connected to the
                                              FTF3545 via a 2-inch nosepiece there is 0".97 ± 0".38 remaining
                                              backfocus with a Sony a900 camera connected to the TCF-S with a T-ring
                                              and 2-inch sleeve. I'll finish off the drawing today and post a pdf in
                                              my photo folder.

                                              Next time this issue is raised there will be an answer available.

                                              Chris Lord

                                              On Sep 03, 2009, at 21:49, Tim Khan wrote:

                                              > I understand, however you can always sell the the TCF-S to get a PDF.
                                              >
                                              > Hopefully your adapters will work accordingly. Another way is what my
                                              > friend does on his 140. He has the robofocus on the left and the FT
                                              > knobs on the right and he just loosens the collar for visual.
                                            • yuri80226
                                              ... Dear friends, here is the latest update for APO110 project. We received all brass and aluminum cast tooling (total48 parts) in the end of August. Machined
                                              Message 22 of 26 , Sep 9, 2009
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                                                --- In tec-scopes@yahoogroups.com, "Yuri" <tec@...> wrote:

                                                > The project going well, see the group front page picture of the set for test plates for objective lenses, it is most time consuming optical work for any new project - done.
                                                > FF lenses are in work (3-lens design), same about cases. Waiting for AL and bronze cast tooling; first glass to come in 2-3 weeks, and Fluorite scheduled for September.
                                                > Working on focuser prototype...
                                                > That is about all!
                                                > Best regards, Yuri
                                                >

                                                Dear friends,
                                                here is the latest update for APO110 project.
                                                We received all brass and aluminum cast tooling (total48 parts) in the end of August. Machined all of them and have started working with glass for the APO110 this week! CaF2 blanks arrived today.
                                                Regards,
                                                Yuri
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