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Re: [William Optics] Adjusting the lens to chip distance on Flattener 3

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  • Steve L
    I`l jump in here and also thank Sander for those links...I didnt know that Edmund Optics had a UK distribution option... bookmarked!! Steve
    Message 1 of 23 , Mar 31, 2009
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      I`l jump in here and also thank Sander for those links...I didnt know
      that Edmund Optics had a UK distribution option... bookmarked!!

      Steve

      stardaddyed wrote:
      > Sander
      >
      > Thanks. The second link is the most important. I didn't realize that the thin ones were available I thought the shortest was a 10mm. Now I know where to get them!
      >
      > Ed
      >
      > --- In William-Optics@yahoogroups.com, Sander Pool <sander@...> wrote:
      >>
      >> Ed,
      >>
      >> I have the baader units and these from Edmund Optics:
      >>
      >> http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=1285
      >>
      >> and
      >>
      >> http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productID=2761
      >>
      >> Together you can make just about any spacer size.
      >>
      >> Sander
      >>
      >> stardaddyed wrote:
      >>> I have a Megrez 90 with the Flattener 3 FR. I know what the lens to
      >>> chip distance should be and I can measure it but I am curious how
      >>> other fine tune that distance? T-thread extenders only come in fixed
      >>> sizes. It is not very conducive to minor tweaking.
      >>>
      >>> Ed
      >>>
      >>>
      >
      >
      >
      >
      > ------------------------------------
      >
      > www.williamoptics.com www.williamopticsracing.comYahoo! Groups Links
      >
      >
      >
    • thomashs2001
      Ed, I have the same setup. What is the lens to chip distance and how do you measure this when using a Canon XTi. Tom
      Message 2 of 23 , Mar 31, 2009
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        Ed,

        I have the same setup. What is the lens to chip distance and how do you measure this when using a Canon XTi.

        Tom

        --- In William-Optics@yahoogroups.com, "stardaddyed" <StarDaddyEd@...> wrote:
        >
        > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip distance should be and I can measure it but I am curious how other fine tune that distance? T-thread extenders only come in fixed sizes. It is not very conducive to minor tweaking.
        >
        > Ed
        >
      • Nigel
        Hi Guys I too have the Megrez 90 and the FF III My initial images with the FF III / M90 combination were disappoitning to sya the least. I then did some
        Message 3 of 23 , Apr 1, 2009
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          Hi Guys

          I too have the Megrez 90 and the FF III

          My initial images with the FF III / M90 combination were disappoitning to sya the least. I then did some experiements with ansd without the FF III in the optical train. I can confirm that the FF III does have an exffect on the optical field but seems to over compensate. See the pictures in my album http://groups.yahoo.com/group/William-Optics/photos/album/1665349697/pic/list

          Now I am wondering if my problem is to do with the distance of the sensor from the FF III ? I have used two different cameras a Nikon D200 and Canon 1000D and both produce the same effect.

          Furthermore I have noticed that the stars in the centre of the image are not perfectly round!

          I have emailed William Optics but so far have got no response whatsoever. One of the reasons I went the WO route was because of, supposedly great post sales support ... :-(

          Does anybody know what the distance should be for the Canon 1000D?


          --- In William-Optics@yahoogroups.com, "Roger" <rog1@...> wrote:
          >
          > I am wondering the same. I used my Field Flattener 3 for the first time the other night and found it did little to flatten the field on my Megrez 90. Researching it I see I need to adjust the distance but that's hard, as you say. I hope someone, anyone, has some insight in to this.
          >
          > However I don't know the distance from chip to lens for my Canon 350D. How did you work out the distance for your chip to lens distance?
          >
          > Thanks,
          > Roger.
          > --
          > ================================================
          > Roger Groom roger[AT]RogerGroom.com
          > http://www.RogerGroom.com/
          > ================================================
          >
          >
          >
          > --- In William-Optics@yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
          > >
          > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip distance should be and I can measure it but I am curious how other fine tune that distance? T-thread extenders only come in fixed sizes. It is not very conducive to minor tweaking.
          > >
          > > Ed
          > >
          >
        • stardaddyed
          Tom For me it not as tough because I have a QHY8 camera. It is specifically an Astro camera so that distance is well documented. Ed
          Message 4 of 23 , Apr 1, 2009
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            Tom

            For me it not as tough because I have a QHY8 camera. It is specifically an Astro camera so that distance is well documented.

            Ed


            --- In William-Optics@yahoogroups.com, "thomashs2001" <tsprecher@...> wrote:
            >
            > Ed,
            >
            > I have the same setup. What is the lens to chip distance and how do you measure this when using a Canon XTi.
            >
            > Tom
            >
            > --- In William-Optics@yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
            > >
            > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip distance should be and I can measure it but I am curious how other fine tune that distance? T-thread extenders only come in fixed sizes. It is not very conducive to minor tweaking.
            > >
            > > Ed
            > >
            >
          • bill_lombardo_bill
            I m in the same situation as Tom s, having a brand new Megrez 90, a FF 3 and a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos adapter
            Message 5 of 23 , Apr 1, 2009
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              I'm in the same situation as Tom's, having a brand new Megrez 90, a FF 3 and a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos adapter measuring 10mm at the beginning of the Eos attach (15.5mm at the end). Maybe one of the Edmund rings can be useful but which one?

              --- In William-Optics@yahoogroups.com, "thomashs2001" <tsprecher@...> wrote:
              >
              > Ed,
              >
              > I have the same setup. What is the lens to chip distance and how do you measure this when using a Canon XTi.
              >
              > Tom
              >
              > --- In William-Optics@yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
              > >
              > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip distance should be and I can measure it but I am curious how other fine tune that distance? T-thread extenders only come in fixed sizes. It is not very conducive to minor tweaking.
              > >
              > > Ed
              > >
              >
            • Sander Pool
              Glad to help Steve and Ed. I struggled quite a bit with flattener spacing with my M110 and FR-III *and* TRF-2008. With a DSLR you re in trouble with FRs that
              Message 6 of 23 , Apr 1, 2009
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                Glad to help Steve and Ed. I struggled quite a bit with flattener
                spacing with my M110 and FR-III *and* TRF-2008. With a DSLR you're in
                trouble with FRs that are not perfectly matched for the scope they are
                attached to. In both cases the optimum distance was shorter than the
                recommended 55mm, more like 41mm. The FR-IV looks like a good option, if
                it can deliver.

                Sander

                Steve L wrote:
                >
                > I`l jump in here and also thank Sander for those links...I didnt know
                > that Edmund Optics had a UK distribution option... bookmarked!!
                >
                > Steve
                >
                > stardaddyed wrote:
                > > Sander
                > >
                > > Thanks. The second link is the most important. I didn't realize that
                > the thin ones were available I thought the shortest was a 10mm. Now I
                > know where to get them!
                > >
                > > Ed
                > >
                > > -
                >
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              • Roy Cummings
                Tom, Optimum FF3 rear flange to sensor distance = 56mm. Camera (Canon 350D) lens mounting flange to sensor plane = 44mm Common T-ring thickness = 10mm. You
                Message 7 of 23 , Apr 1, 2009
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                  Tom,

                   

                  Optimum FF3 rear flange to sensor distance = 56mm.

                  Camera (Canon 350D) lens mounting flange to sensor plane = 44mm

                  Common T-ring thickness = 10mm. You will have to measure yours.

                  You should need the 2mm spacer.

                  I used an o-ring and compressed it until the distance was correct.

                   

                  Roy

                   

                  -----Original Message-----
                  From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com] On Behalf Of bill_lombardo_bill
                  Sent: Wednesday, April 01, 2009 11:58 AM
                  To: William-Optics@yahoogroups.com
                  Subject: [William Optics] Re: Adjusting the lens to chip distance on Flattener 3

                   

                  I'm in the same situation as Tom's, having a brand new Megrez 90, a FF 3 and a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos adapter measuring 10mm at the beginning of the Eos attach (15.5mm at the end). Maybe one of the Edmund rings can be useful but which one?

                  --- In William-Optics@ yahoogroups. com, "thomashs2001" <tsprecher@. ..> wrote:

                  >
                  > Ed,
                  >
                  > I have the same setup. What is the lens to chip distance and how do you
                  measure this when using a Canon XTi.
                  >
                  > Tom
                  >
                  > --- In William-Optics@ yahoogroups. com,
                  "stardaddyed" <StarDaddyEd@ > wrote:
                  > >
                  > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to
                  chip distance should be and I can measure it but I am curious how other fine tune that distance? T-thread extenders only come in fixed sizes. It is not very conducive to minor tweaking.
                  > >
                  > > Ed
                  > >
                  >

                • Gianluca Sordiglioni
                  On my Nikon D90, distance is 46.5mm. My T2 ring is 10mm; I m 0.5mm out. But as far I know there should be a 1mm tollerance.
                  Message 8 of 23 , Apr 2, 2009
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                    On my Nikon D90, distance is 46.5mm. My T2 ring is 10mm; I'm 0.5mm out.
                    But as far I know there should be a 1mm tollerance.



                    > Optimum FF3 rear flange to sensor distance = 56mm.
                    >
                    > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                    >
                    > Common T-ring thickness = 10mm. You will have to measure yours.
                    >
                    > You should need the 2mm spacer.
                    >
                    > I used an o-ring and compressed it until the distance was correct.
                  • bill_lombardo_bill
                    Roy, I thank you a lot for your precise information about Canon 350 D and FF 3. Having a T2 connector measuring 10mm, I have already ordered an Edmund brass
                    Message 9 of 23 , Apr 2, 2009
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                      Roy,

                      I thank you a lot for your precise information about Canon 350 D and FF 3. Having a T2 connector measuring 10mm, I have already ordered an Edmund brass ring of 2mm as per your kind calculation.
                      Best Regards

                      --- In William-Optics@yahoogroups.com, "Roy Cummings" <tr_cummings@...> wrote:
                      >
                      > Tom,
                      >
                      >
                      >
                      > Optimum FF3 rear flange to sensor distance = 56mm.
                      >
                      > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                      >
                      > Common T-ring thickness = 10mm. You will have to measure yours.
                      >
                      > You should need the 2mm spacer.
                      >
                      > I used an o-ring and compressed it until the distance was correct.
                      >
                      >
                      >
                      > Roy
                      >
                      >
                      >
                      > -----Original Message-----
                      > From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
                      > On Behalf Of bill_lombardo_bill
                      > Sent: Wednesday, April 01, 2009 11:58 AM
                      > To: William-Optics@yahoogroups.com
                      > Subject: [William Optics] Re: Adjusting the lens to chip distance on
                      > Flattener 3
                      >
                      >
                      >
                      > I'm in the same situation as Tom's, having a brand new Megrez 90, a FF 3 and
                      > a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos
                      > adapter measuring 10mm at the beginning of the Eos attach (15.5mm at the
                      > end). Maybe one of the Edmund rings can be useful but which one?
                      >
                      > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                      > yahoogroups.com, "thomashs2001" <tsprecher@> wrote:
                      > >
                      > > Ed,
                      > >
                      > > I have the same setup. What is the lens to chip distance and how do you
                      > measure this when using a Canon XTi.
                      > >
                      > > Tom
                      > >
                      > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                      > yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
                      > > >
                      > > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip
                      > distance should be and I can measure it but I am curious how other fine tune
                      > that distance? T-thread extenders only come in fixed sizes. It is not very
                      > conducive to minor tweaking.
                      > > >
                      > > > Ed
                      > > >
                      > >
                      >
                    • Sander Pool
                      The way it was explained to me is that the distance from T-ring to sensor in a DSLR is standard and a holdover from the old 35mm days. That s why at least
                      Message 10 of 23 , Apr 2, 2009
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                        The way it was explained to me is that the distance from T-ring to
                        sensor in a DSLR is standard and a holdover from the 'old' 35mm days.
                        That's why at least some FRs (TRF-2008, FR-III) specify a 55mm (or so)
                        optimum distance. It would be better if these FRs were made for say a
                        70mm distance so there was some room to adjust the distance. Based on my
                        admittedly limited experience it seems the recommended distance for
                        these flatteners is just a wild guess. Not just at WO but TV as well. If
                        I had used a DSLR I wouldn't have the flat field I have now. In my case
                        the optimum distance was around 41mm in both cases.

                        I think that the FR-IV is the first acknowledgment of this problem and
                        an attempt to fix it. If the mechanical aspects hold up (ie. it doesn't
                        introduce flexure and keeps the camera square) this should be *the* FR
                        to get.

                        Sander

                        Gianluca Sordiglioni wrote:
                        >
                        > On my Nikon D90, distance is 46.5mm. My T2 ring is 10mm; I'm 0.5mm out.
                        > But as far I know there should be a 1mm tollerance.
                        >
                        > > Optimum FF3 rear flange to sensor distance = 56mm.
                        > >
                        > > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                        > >
                        > > Common T-ring thickness = 10mm. You will have to measure yours.
                        > >
                        > > You should need the 2mm spacer.
                        > >
                        > > I used an o-ring and compressed it until the distance was correct.
                        >
                        >
                      • thomashs2001
                        Roy, Thanks for the info, I ll try the O ring route and then purchase a brass spacer when I know what depth I need. Tom
                        Message 11 of 23 , Apr 2, 2009
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                          Roy,

                          Thanks for the info, I'll try the O ring route and then purchase a brass spacer when I know what depth I need.

                          Tom
                          --- In William-Optics@yahoogroups.com, "Roy Cummings" <tr_cummings@...> wrote:
                          >
                          > Tom,
                          >
                          >
                          >
                          > Optimum FF3 rear flange to sensor distance = 56mm.
                          >
                          > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                          >
                          > Common T-ring thickness = 10mm. You will have to measure yours.
                          >
                          > You should need the 2mm spacer.
                          >
                          > I used an o-ring and compressed it until the distance was correct.
                          >
                          >
                          >
                          > Roy
                          >
                          >
                          >
                          > -----Original Message-----
                          > From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
                          > On Behalf Of bill_lombardo_bill
                          > Sent: Wednesday, April 01, 2009 11:58 AM
                          > To: William-Optics@yahoogroups.com
                          > Subject: [William Optics] Re: Adjusting the lens to chip distance on
                          > Flattener 3
                          >
                          >
                          >
                          > I'm in the same situation as Tom's, having a brand new Megrez 90, a FF 3 and
                          > a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos
                          > adapter measuring 10mm at the beginning of the Eos attach (15.5mm at the
                          > end). Maybe one of the Edmund rings can be useful but which one?
                          >
                          > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                          > yahoogroups.com, "thomashs2001" <tsprecher@> wrote:
                          > >
                          > > Ed,
                          > >
                          > > I have the same setup. What is the lens to chip distance and how do you
                          > measure this when using a Canon XTi.
                          > >
                          > > Tom
                          > >
                          > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                          > yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
                          > > >
                          > > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip
                          > distance should be and I can measure it but I am curious how other fine tune
                          > that distance? T-thread extenders only come in fixed sizes. It is not very
                          > conducive to minor tweaking.
                          > > >
                          > > > Ed
                          > > >
                          > >
                          >
                        • bill_lombardo_bill
                          Maybe I m an idiot but every time I attach my FF 3 to the T/Eos ring and this to my 350 D, I finish with the chrome screw of the FF which hurts the camera
                          Message 12 of 23 , Apr 3, 2009
                          • 0 Attachment
                            Maybe I'm an idiot but every time I attach my FF 3 to the T/Eos ring and this to my 350 D, I finish with the chrome screw of the FF which hurts the camera flash holder that protrudes (just under the "Canon" mark). I purchased another T/Eos ring: same result. Please tell me that it's me the idiot and that there is a simple way to avoid such frustration that seems to me scientifically conceived to impede the very use of the screw. This way you cannot make use of the screw to rotate the camera when you take images...
                            Thanks for any help to this regard.


                            --- In William-Optics@yahoogroups.com, "thomashs2001" <tsprecher@...> wrote:
                            >
                            > Roy,
                            >
                            > Thanks for the info, I'll try the O ring route and then purchase a brass spacer when I know what depth I need.
                            >
                            > Tom
                            > --- In William-Optics@yahoogroups.com, "Roy Cummings" <tr_cummings@> wrote:
                            > >
                            > > Tom,
                            > >
                            > >
                            > >
                            > > Optimum FF3 rear flange to sensor distance = 56mm.
                            > >
                            > > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                            > >
                            > > Common T-ring thickness = 10mm. You will have to measure yours.
                            > >
                            > > You should need the 2mm spacer.
                            > >
                            > > I used an o-ring and compressed it until the distance was correct.
                            > >
                            > >
                            > >
                            > > Roy
                            > >
                            > >
                            > >
                            > > -----Original Message-----
                            > > From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
                            > > On Behalf Of bill_lombardo_bill
                            > > Sent: Wednesday, April 01, 2009 11:58 AM
                            > > To: William-Optics@yahoogroups.com
                            > > Subject: [William Optics] Re: Adjusting the lens to chip distance on
                            > > Flattener 3
                            > >
                            > >
                            > >
                            > > I'm in the same situation as Tom's, having a brand new Megrez 90, a FF 3 and
                            > > a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos
                            > > adapter measuring 10mm at the beginning of the Eos attach (15.5mm at the
                            > > end). Maybe one of the Edmund rings can be useful but which one?
                            > >
                            > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                            > > yahoogroups.com, "thomashs2001" <tsprecher@> wrote:
                            > > >
                            > > > Ed,
                            > > >
                            > > > I have the same setup. What is the lens to chip distance and how do you
                            > > measure this when using a Canon XTi.
                            > > >
                            > > > Tom
                            > > >
                            > > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                            > > yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
                            > > > >
                            > > > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip
                            > > distance should be and I can measure it but I am curious how other fine tune
                            > > that distance? T-thread extenders only come in fixed sizes. It is not very
                            > > conducive to minor tweaking.
                            > > > >
                            > > > > Ed
                            > > > >
                            > > >
                            > >
                            >
                          • Jaap van 't Leven
                            I had the same problem, but fixed it by adjusting the T-ring. Most T-rings consist of 2 parts: the actual T-ring and the part with the EOS (or other) mount. If
                            Message 13 of 23 , Apr 3, 2009
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                              I had the same problem, but fixed it by adjusting the T-ring.
                              Most T-rings consist of 2 parts: the actual T-ring and the part with the EOS (or other) mount.
                              If you loosen the tiny screws keeping those 2 parts together, you can rotate one of the rings.

                              Jaap.

                              On Fri, Apr 3, 2009 at 3:29 PM, bill_lombardo_bill <bill_lombardo@...> wrote:

                              Maybe I'm an idiot but every time I attach my FF 3 to the T/Eos ring and this to my 350 D, I finish with the chrome screw of the FF which hurts the camera flash holder that protrudes (just under the "Canon" mark). I purchased another T/Eos ring: same result. Please tell me that it's me the idiot and that there is a simple way to avoid such frustration that seems to me scientifically conceived to impede the very use of the screw. This way you cannot make use of the screw to rotate the camera when you take images...
                              Thanks for any help to this regard.



                              --- In William-Optics@yahoogroups.com, "thomashs2001" <tsprecher@...> wrote:
                              >
                              > Roy,
                              >
                              > Thanks for the info, I'll try the O ring route and then purchase a brass spacer when I know what depth I need.
                              >
                              > Tom
                              > --- In William-Optics@yahoogroups.com, "Roy Cummings" <tr_cummings@> wrote:
                              > >
                              > > Tom,
                              > >
                              > >
                              > >
                              > > Optimum FF3 rear flange to sensor distance = 56mm.
                              > >
                              > > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                              > >
                              > > Common T-ring thickness = 10mm. You will have to measure yours.
                              > >
                              > > You should need the 2mm spacer.
                              > >
                              > > I used an o-ring and compressed it until the distance was correct.
                              > >
                              > >
                              > >
                              > > Roy
                              > >
                              > >
                              > >
                              > > -----Original Message-----
                              > > From: William-Optics@yahoogroups.com [mailto:William-Optics@yahoogroups.com]
                              > > On Behalf Of bill_lombardo_bill
                              > > Sent: Wednesday, April 01, 2009 11:58 AM
                              > > To: William-Optics@yahoogroups.com
                              > > Subject: [William Optics] Re: Adjusting the lens to chip distance on
                              > > Flattener 3
                              > >
                              > >
                              > >
                              > > I'm in the same situation as Tom's, having a brand new Megrez 90, a FF 3 and
                              > > a Canon 350 D (which is a XTi, as far as I know)as well as a T-system Eos
                              > > adapter measuring 10mm at the beginning of the Eos attach (15.5mm at the
                              > > end). Maybe one of the Edmund rings can be useful but which one?
                              > >
                              > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                              > > yahoogroups.com, "thomashs2001" <tsprecher@> wrote:
                              > > >
                              > > > Ed,
                              > > >
                              > > > I have the same setup. What is the lens to chip distance and how do you
                              > > measure this when using a Canon XTi.
                              > > >
                              > > > Tom
                              > > >
                              > > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com>
                              > > yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
                              > > > >
                              > > > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip
                              > > distance should be and I can measure it but I am curious how other fine tune
                              > > that distance? T-thread extenders only come in fixed sizes. It is not very
                              > > conducive to minor tweaking.
                              > > > >
                              > > > > Ed
                              > > > >
                              > > >
                              > >
                              >


                            • bill_lombardo_bill
                              Jaap, thanks for illuminating me. Best Regards
                              Message 14 of 23 , Apr 3, 2009
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                                Jaap,

                                thanks for illuminating me.
                                Best Regards
                                --- In William-Optics@yahoogroups.com, "Jaap van 't Leven" <jvtleven@...> wrote:
                                >
                                > I had the same problem, but fixed it by adjusting the T-ring.
                                > Most T-rings consist of 2 parts: the actual T-ring and the part with the EOS
                                > (or other) mount.
                                > If you loosen the tiny screws keeping those 2 parts together, you can rotate
                                > one of the rings.
                                >
                                > Jaap.
                                >
                                > On Fri, Apr 3, 2009 at 3:29 PM, bill_lombardo_bill
                                > <bill_lombardo@...>wrote:
                                >
                                > > Maybe I'm an idiot but every time I attach my FF 3 to the T/Eos ring and
                                > > this to my 350 D, I finish with the chrome screw of the FF which hurts the
                                > > camera flash holder that protrudes (just under the "Canon" mark). I
                                > > purchased another T/Eos ring: same result. Please tell me that it's me the
                                > > idiot and that there is a simple way to avoid such frustration that seems to
                                > > me scientifically conceived to impede the very use of the screw. This way
                                > > you cannot make use of the screw to rotate the camera when you take
                                > > images...
                                > > Thanks for any help to this regard.
                                > >
                                > >
                                > > --- In William-Optics@yahoogroups.com <William-Optics%40yahoogroups.com>,
                                > > "thomashs2001" <tsprecher@> wrote:
                                > > >
                                > > > Roy,
                                > > >
                                > > > Thanks for the info, I'll try the O ring route and then purchase a brass
                                > > spacer when I know what depth I need.
                                > > >
                                > > > Tom
                                > > > --- In William-Optics@yahoogroups.com <William-Optics%40yahoogroups.com>,
                                > > "Roy Cummings" <tr_cummings@> wrote:
                                > > > >
                                > > > > Tom,
                                > > > >
                                > > > >
                                > > > >
                                > > > > Optimum FF3 rear flange to sensor distance = 56mm.
                                > > > >
                                > > > > Camera (Canon 350D) lens mounting flange to sensor plane = 44mm
                                > > > >
                                > > > > Common T-ring thickness = 10mm. You will have to measure yours.
                                > > > >
                                > > > > You should need the 2mm spacer.
                                > > > >
                                > > > > I used an o-ring and compressed it until the distance was correct.
                                > > > >
                                > > > >
                                > > > >
                                > > > > Roy
                                > > > >
                                > > > >
                                > > > >
                                > > > > -----Original Message-----
                                > > > > From: William-Optics@yahoogroups.com<William-Optics%40yahoogroups.com>[mailto:
                                > > William-Optics@yahoogroups.com <William-Optics%40yahoogroups.com>]
                                > > > > On Behalf Of bill_lombardo_bill
                                > > > > Sent: Wednesday, April 01, 2009 11:58 AM
                                > > > > To: William-Optics@yahoogroups.com <William-Optics%40yahoogroups.com>
                                > > > > Subject: [William Optics] Re: Adjusting the lens to chip distance on
                                > > > > Flattener 3
                                > > > >
                                > > > >
                                > > > >
                                > > > > I'm in the same situation as Tom's, having a brand new Megrez 90, a FF
                                > > 3 and
                                > > > > a Canon 350 D (which is a XTi, as far as I know)as well as a T-system
                                > > Eos
                                > > > > adapter measuring 10mm at the beginning of the Eos attach (15.5mm at
                                > > the
                                > > > > end). Maybe one of the Edmund rings can be useful but which one?
                                > > > >
                                > > > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com<William-Optics%2540yahoogroups.com>
                                > > >
                                > > > > yahoogroups.com, "thomashs2001" <tsprecher@> wrote:
                                > > > > >
                                > > > > > Ed,
                                > > > > >
                                > > > > > I have the same setup. What is the lens to chip distance and how do
                                > > you
                                > > > > measure this when using a Canon XTi.
                                > > > > >
                                > > > > > Tom
                                > > > > >
                                > > > > > --- In William-Optics@ <mailto:William-Optics%40yahoogroups.com<William-Optics%2540yahoogroups.com>
                                > > >
                                > > > > yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
                                > > > > > >
                                > > > > > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to
                                > > chip
                                > > > > distance should be and I can measure it but I am curious how other fine
                                > > tune
                                > > > > that distance? T-thread extenders only come in fixed sizes. It is not
                                > > very
                                > > > > conducive to minor tweaking.
                                > > > > > >
                                > > > > > > Ed
                                > > > > > >
                                > > > > >
                                > > > >
                                > > >
                                > >
                                > >
                                > >
                                >
                              • jose.mtanous
                                Hi Nigel, I ve seen your pictures and they look field rotated. The best way to test flatness is to shoot a bright star on different places of the sensor, on
                                Message 15 of 23 , Apr 3, 2009
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                                  Hi Nigel,

                                  I've seen your pictures and they look field rotated.

                                  The best way to test flatness is to shoot a bright star on different places of the sensor, on the center and edges with fast exposures.

                                  Cheers,

                                  Jose


                                  --- In William-Optics@yahoogroups.com, "Nigel" <nwgentuk@...> wrote:
                                  >
                                  > Hi Guys
                                  >
                                  > I too have the Megrez 90 and the FF III
                                  >
                                  > My initial images with the FF III / M90 combination were disappoitning to sya the least. I then did some experiements with ansd without the FF III in the optical train. I can confirm that the FF III does have an exffect on the optical field but seems to over compensate. See the pictures in my album http://groups.yahoo.com/group/William-Optics/photos/album/1665349697/pic/list
                                  >
                                  > Now I am wondering if my problem is to do with the distance of the sensor from the FF III ? I have used two different cameras a Nikon D200 and Canon 1000D and both produce the same effect.
                                  >
                                  > Furthermore I have noticed that the stars in the centre of the image are not perfectly round!
                                  >
                                  > I have emailed William Optics but so far have got no response whatsoever. One of the reasons I went the WO route was because of, supposedly great post sales support ... :-(
                                  >
                                  > Does anybody know what the distance should be for the Canon 1000D?
                                  >
                                  >
                                  > --- In William-Optics@yahoogroups.com, "Roger" <rog1@> wrote:
                                  > >
                                  > > I am wondering the same. I used my Field Flattener 3 for the first time the other night and found it did little to flatten the field on my Megrez 90. Researching it I see I need to adjust the distance but that's hard, as you say. I hope someone, anyone, has some insight in to this.
                                  > >
                                  > > However I don't know the distance from chip to lens for my Canon 350D. How did you work out the distance for your chip to lens distance?
                                  > >
                                  > > Thanks,
                                  > > Roger.
                                  > > --
                                  > > ================================================
                                  > > Roger Groom roger[AT]RogerGroom.com
                                  > > http://www.RogerGroom.com/
                                  > > ================================================
                                  > >
                                  > >
                                  > >
                                  > > --- In William-Optics@yahoogroups.com, "stardaddyed" <StarDaddyEd@> wrote:
                                  > > >
                                  > > > I have a Megrez 90 with the Flattener 3 FR. I know what the lens to chip distance should be and I can measure it but I am curious how other fine tune that distance? T-thread extenders only come in fixed sizes. It is not very conducive to minor tweaking.
                                  > > >
                                  > > > Ed
                                  > > >
                                  > >
                                  >
                                • Roger
                                  Bill, I have exactly the same problem with my 350D. I find that I can have the camera connected and only just by a very small margin will the screw fit without
                                  Message 16 of 23 , Apr 5, 2009
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                                    Bill,

                                    I have exactly the same problem with my 350D. I find that I can have the camera connected and only just by a very small margin will the screw fit without hitting the flash. I am going to try finding a smaller thumb screw to use instead, I think some Meade ones I have around are smaller in diameter so might not be a problem.

                                    Poor decision by WO on where to put the screw I think

                                    Roger.

                                    ================================================
                                    Roger Groom roger[AT]RogerGroom.com
                                    http://www.RogerGroom.com/
                                    ================================================

                                    --- In William-Optics@yahoogroups.com, "bill_lombardo_bill" <bill_lombardo@...> wrote:
                                    >
                                    > Maybe I'm an idiot but every time I attach my FF 3 to the T/Eos ring and this to my 350 D, I finish with the chrome screw of the FF which hurts the camera flash holder that protrudes (just under the "Canon" mark). I purchased another T/Eos ring: same result. Please tell me that it's me the idiot and that there is a simple way to avoid such frustration that seems to me scientifically conceived to impede the very use of the screw. This way you cannot make use of the screw to rotate the camera when you take images...
                                    > Thanks for any help to this regard.
                                    >
                                  • Perry Holcomb
                                    Hey Roger, See posts following Bill s initial post. The answer is there!! G day, Perry ... From: Roger Subject: [William Optics] Re:
                                    Message 17 of 23 , Apr 5, 2009
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                                      Hey Roger,

                                      See posts following Bill's initial post.

                                      The answer is there!!

                                      G'day,

                                      Perry

                                      --- On Sun, 4/5/09, Roger <rog1@...> wrote:

                                      From: Roger <rog1@...>
                                      Subject: [William Optics] Re: Flattener 3 adjustment screw
                                      To: William-Optics@yahoogroups.com
                                      Date: Sunday, April 5, 2009, 8:07 PM

                                      Bill,

                                      I have exactly the same problem with my 350D. I find that I can have the camera connected and only just by a very small margin will the screw fit without hitting the flash. I am going to try finding a smaller thumb screw to use instead, I think some Meade ones I have around are smaller in diameter so might not be a problem.

                                      Poor decision by WO on where to put the screw I think

                                      Roger.

                                      ============ ========= ========= ========= =========
                                      Roger Groom roger[AT]RogerGroom .com
                                      http://www.RogerGro om.com/
                                      ============ ========= ========= ========= =========

                                      --- In William-Optics@ yahoogroups. com, "bill_lombardo_ bill" <bill_lombardo@ ...> wrote:
                                      >
                                      > Maybe I'm an idiot but every time I attach my FF 3 to the T/Eos ring and this to my 350 D, I finish with the chrome screw of the FF which hurts the camera flash holder that protrudes (just under the "Canon" mark). I purchased another T/Eos ring: same result. Please tell me that it's me the idiot and that there is a simple way to avoid such frustration that seems to me scientifically conceived to impede the very use of the screw. This way you cannot make use of the screw to rotate the camera when you take images...
                                      > Thanks for any help to this regard.
                                      >


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