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Re: CCD Imaging Problems.

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  • Wade Van Arsdale
    Hi Mark, Glad to help out. Roland at AP can discuss options with you and he is always a great source to get the best setup for your specific rig using his
    Message 1 of 19 , Oct 7, 2009
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      Hi Mark,
      Glad to help out. Roland at AP can discuss options with you and
      he is always a great source to get the best setup for your specific
      rig using his parts. Good luck and clear skies!

      Wade

      /////////////////////////////

      --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@...> wrote:
      >
      > Wow, this is great info! Thanks, Wade!
      >
      > I appreciate you going into detail for this issue.
      >
      > I will look into the AP fr's. I am just glad to know why my stars are smeared. Thank you.
      >
      > -Mark.
      >
      > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
      > >
      > > Hi Mark,
      > > Re. the Meade focal reducer on ACF systems, the Meade f.r.'s
      > > (and Celestron's too) have a "negative coma" designed into their
      > > lens elements to correct for the inherent coma in their older SCT's
      > > with the older optical prescription. This negative coma was the
      > > same amount as the optical train, just with opposite curvature to
      > > cancel the coma out.
      > >
      > > But when Meade came out with the new ACF design, the optical
      > > prescription was different (flatter), so the focal reducer's own
      > > optical prescription was no longer a match for that system. Note,
      > > Celestron will now have the same problem with their new flat-field
      > > SCT's they have just announced.
      > >
      > > So the problem is you have to use a focal reducer that is designed
      > > for optical systems that are very "flat" (with little to no inherent
      > > field curvature). As far as I know, neither Meade nor Celestron
      > > offer such a f.r. (yet).
      > >
      > > You might consider the 27TVPH f.r. from Astro-Physics:
      > > http://tinyurl.com/2pbnys
      > >
      > > You'll also need their ADASCTLM27 visual back adapter for your Meade:
      > > http://tinyurl.com/2uftd4
      > >
      > > Be aware also, that you will not be reducing the focal length much
      > > at all with this focal reducer. Here is a link to the focal
      > > reducer's optical characteristics:
      > > http://tinyurl.com/63qetp
      > >
      > > If back-focus is a concern, this page will help you calculate it:
      > > http://www.wilmslowastro.com/software/formulae.htm#FR
      > >
      > > The correct chip-to-edge of f.r. body distance is 118mm for 0.75x
      > > focal reduction. For more focal reduction, move this distance
      > > outward with extra spacers, etc.... You can get spacers from AP
      > > (check the above AP links).
      > >
      > > You can get a T-ring threaded cap here to mate this f.r. to
      > > your camera:
      > > http://www.rcopticalsystems.com/accessories/
      > >
      > > Just tell them you need the T-ring adapter with standard AP 2.7
      > > inch threades (pic at bottom of above link).
      > >
      > > AP also has a clamping back-end adapter if your camera attaches
      > > with a 2 inch nosepiece designed for focuser drawtubes (PN ADA2003):
      > > http://tinyurl.com/3bsy6c
      > >
      > > You might also want to consider the CCDT67 focal reducer from
      > > Astro-Physics as well:
      > > http://tinyurl.com/yrjywn
      > >
      > > It is designed for systems of f/9 or longer and might work for
      > > your Meade. I know for certain that the 27TVPH will work on Meade
      > > ACF systems, because I worked with a Meade 14 inch ACF owner to
      > > test the f.r. on that system. It produced round stars to the edges
      > > of the field with an ST-2000XM camera. However, this camera only
      > > requires a 15mm diameter image circle to cover the chip. Larger,
      > > APS-sized chips (30mm image circle or larger) were not tested in
      > > our sessions. So I don't know if the correction is as good with
      > > those types of cameras. If you are using a Meade camera, it should
      > > be fine though on field correction as those chips are not that
      > > large compared to DSLR's and other APS-sized chips.
      > >
      > > Hope this helps,
      > > Wade Van Arsdale
      > > Little Rock, AR., USA
      > >
      > > --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@> wrote:
      > > >
      > > > Hi all. I have recently been working with a DSI II Pro CCD on an LX90 10 inch ACF which is collimated perfectly for visual observing. In most of my images, the brighter stars seem to have 2 projections coming off of them. When you overexpose the f/3 reduced pic, all the stars have this coming out from the center of pic. I am using a focal reducer and have had problems with focusing down to an f/3 which is what this picture was taken in, I use a botinov mask to focus. If anyone has seen this type problem, please let me know what it is. In a lot of my f/5 pics this is not as much an issue, except with the brighter stars on the periphery of the pic. I did have some periphery stars making smudges, but found out my IR filter was fogging up and was able to correct by wrapping a dew heater around the camera spacer.
      > > >
      > > > http://groups.yahoo.com/group/ccd-newastro/photos/album/771948104/pic/1434629078/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
      > > >
      > > > Thank You,
      > > >
      > > > Mark.
      > > >
      > >
      >
    • Keith
      I will recommend the AP focal reducers for ACF systems with small to medium size chips also. I have both 27TVPH and CCD67 reducers and they work wonderfully
      Message 2 of 19 , Oct 7, 2009
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        I will recommend the AP focal reducers for ACF systems with small to medium size chips also. I have both 27TVPH and CCD67 reducers and they work wonderfully well with my ST-2K camera. Different story with the STL-11K. The .67X form factor is too small to fully illuminate the 35mm film format size of the STL. The .75X reducer does a much better job and only fails in the last 10% of the frame's corners. I have not tested the .75X with a DSLR however. Because the APS-C format is slightly smaller than full frame 35mm, you might get away with acceptably small coma in the corners.

        Keith


        --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@...> wrote:
        >
        > Hi Mark,
        > Re. the Meade focal reducer on ACF systems, the Meade f.r.'s
        > (and Celestron's too) have a "negative coma" designed into their
        > lens elements to correct for the inherent coma in their older SCT's
        > with the older optical prescription. This negative coma was the
        > same amount as the optical train, just with opposite curvature to
        > cancel the coma out.
        >
        > But when Meade came out with the new ACF design, the optical
        > prescription was different (flatter), so the focal reducer's own
        > optical prescription was no longer a match for that system. Note,
        > Celestron will now have the same problem with their new flat-field
        > SCT's they have just announced.
        >
        > So the problem is you have to use a focal reducer that is designed
        > for optical systems that are very "flat" (with little to no inherent
        > field curvature). As far as I know, neither Meade nor Celestron
        > offer such a f.r. (yet).
        >
        > You might consider the 27TVPH f.r. from Astro-Physics:
        > http://tinyurl.com/2pbnys
        >
        > You'll also need their ADASCTLM27 visual back adapter for your Meade:
        > http://tinyurl.com/2uftd4
        >
        > Be aware also, that you will not be reducing the focal length much
        > at all with this focal reducer. Here is a link to the focal
        > reducer's optical characteristics:
        > http://tinyurl.com/63qetp
        >
        > If back-focus is a concern, this page will help you calculate it:
        > http://www.wilmslowastro.com/software/formulae.htm#FR
        >
        > The correct chip-to-edge of f.r. body distance is 118mm for 0.75x
        > focal reduction. For more focal reduction, move this distance
        > outward with extra spacers, etc.... You can get spacers from AP
        > (check the above AP links).
        >
        > You can get a T-ring threaded cap here to mate this f.r. to
        > your camera:
        > http://www.rcopticalsystems.com/accessories/
        >
        > Just tell them you need the T-ring adapter with standard AP 2.7
        > inch threades (pic at bottom of above link).
        >
        > AP also has a clamping back-end adapter if your camera attaches
        > with a 2 inch nosepiece designed for focuser drawtubes (PN ADA2003):
        > http://tinyurl.com/3bsy6c
        >
        > You might also want to consider the CCDT67 focal reducer from
        > Astro-Physics as well:
        > http://tinyurl.com/yrjywn
        >
        > It is designed for systems of f/9 or longer and might work for
        > your Meade. I know for certain that the 27TVPH will work on Meade
        > ACF systems, because I worked with a Meade 14 inch ACF owner to
        > test the f.r. on that system. It produced round stars to the edges
        > of the field with an ST-2000XM camera. However, this camera only
        > requires a 15mm diameter image circle to cover the chip. Larger,
        > APS-sized chips (30mm image circle or larger) were not tested in
        > our sessions. So I don't know if the correction is as good with
        > those types of cameras. If you are using a Meade camera, it should
        > be fine though on field correction as those chips are not that
        > large compared to DSLR's and other APS-sized chips.
        >
        > Hope this helps,
        > Wade Van Arsdale
        > Little Rock, AR., USA
        >
        > --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@> wrote:
        > >
        > > Hi all. I have recently been working with a DSI II Pro CCD on an LX90 10 inch ACF which is collimated perfectly for visual observing. In most of my images, the brighter stars seem to have 2 projections coming off of them. When you overexpose the f/3 reduced pic, all the stars have this coming out from the center of pic. I am using a focal reducer and have had problems with focusing down to an f/3 which is what this picture was taken in, I use a botinov mask to focus. If anyone has seen this type problem, please let me know what it is. In a lot of my f/5 pics this is not as much an issue, except with the brighter stars on the periphery of the pic. I did have some periphery stars making smudges, but found out my IR filter was fogging up and was able to correct by wrapping a dew heater around the camera spacer.
        > >
        > > http://groups.yahoo.com/group/ccd-newastro/photos/album/771948104/pic/1434629078/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
        > >
        > > Thank You,
        > >
        > > Mark.
        > >
        >
      • Wade Van Arsdale
        Thanks for the additional info, Keith. That s good to know the CCD67 f.r. works too with the Meade ACF SCT s on small-to-medium chip cameras. We had not
        Message 3 of 19 , Oct 7, 2009
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          Thanks for the additional info, Keith. That's good to know the
          CCD67 f.r. works too with the Meade ACF SCT's on small-to-medium chip
          cameras. We had not tested that one, only the 27TVPH. It makes
          sense both f.r.'s would work with a scope that is fairly well "flat"
          in field curvature. Both of those f.r.'s were designed for flat
          fields with little curvature. Hopefully those two f.r.'s will also
          perform well on the new Celestron flat-field SCT's too. AP is now
          offering a visual back adapter for the 27TVPH that fits the Celestron
          C14 and C11 OTA's.

          Thanks again for the help.

          Cheers,
          Wade

          --- In ccd-newastro@yahoogroups.com, "Keith" <keith.myers@...> wrote:
          >
          > I will recommend the AP focal reducers for ACF systems with small to medium size chips also. I have both 27TVPH and CCD67 reducers and they work wonderfully well with my ST-2K camera. Different story with the STL-11K. The .67X form factor is too small to fully illuminate the 35mm film format size of the STL. The .75X reducer does a much better job and only fails in the last 10% of the frame's corners. I have not tested the .75X with a DSLR however. Because the APS-C format is slightly smaller than full frame 35mm, you might get away with acceptably small coma in the corners.
          >
          > Keith
          >
          >
          > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
          > >
          > > Hi Mark,
          > > Re. the Meade focal reducer on ACF systems, the Meade f.r.'s
          > > (and Celestron's too) have a "negative coma" designed into their
          > > lens elements to correct for the inherent coma in their older SCT's
          > > with the older optical prescription. This negative coma was the
          > > same amount as the optical train, just with opposite curvature to
          > > cancel the coma out.
          > >
          > > But when Meade came out with the new ACF design, the optical
          > > prescription was different (flatter), so the focal reducer's own
          > > optical prescription was no longer a match for that system. Note,
          > > Celestron will now have the same problem with their new flat-field
          > > SCT's they have just announced.
          > >
          > > So the problem is you have to use a focal reducer that is designed
          > > for optical systems that are very "flat" (with little to no inherent
          > > field curvature). As far as I know, neither Meade nor Celestron
          > > offer such a f.r. (yet).
          > >
          > > You might consider the 27TVPH f.r. from Astro-Physics:
          > > http://tinyurl.com/2pbnys
          > >
          > > You'll also need their ADASCTLM27 visual back adapter for your Meade:
          > > http://tinyurl.com/2uftd4
          > >
          > > Be aware also, that you will not be reducing the focal length much
          > > at all with this focal reducer. Here is a link to the focal
          > > reducer's optical characteristics:
          > > http://tinyurl.com/63qetp
          > >
          > > If back-focus is a concern, this page will help you calculate it:
          > > http://www.wilmslowastro.com/software/formulae.htm#FR
          > >
          > > The correct chip-to-edge of f.r. body distance is 118mm for 0.75x
          > > focal reduction. For more focal reduction, move this distance
          > > outward with extra spacers, etc.... You can get spacers from AP
          > > (check the above AP links).
          > >
          > > You can get a T-ring threaded cap here to mate this f.r. to
          > > your camera:
          > > http://www.rcopticalsystems.com/accessories/
          > >
          > > Just tell them you need the T-ring adapter with standard AP 2.7
          > > inch threades (pic at bottom of above link).
          > >
          > > AP also has a clamping back-end adapter if your camera attaches
          > > with a 2 inch nosepiece designed for focuser drawtubes (PN ADA2003):
          > > http://tinyurl.com/3bsy6c
          > >
          > > You might also want to consider the CCDT67 focal reducer from
          > > Astro-Physics as well:
          > > http://tinyurl.com/yrjywn
          > >
          > > It is designed for systems of f/9 or longer and might work for
          > > your Meade. I know for certain that the 27TVPH will work on Meade
          > > ACF systems, because I worked with a Meade 14 inch ACF owner to
          > > test the f.r. on that system. It produced round stars to the edges
          > > of the field with an ST-2000XM camera. However, this camera only
          > > requires a 15mm diameter image circle to cover the chip. Larger,
          > > APS-sized chips (30mm image circle or larger) were not tested in
          > > our sessions. So I don't know if the correction is as good with
          > > those types of cameras. If you are using a Meade camera, it should
          > > be fine though on field correction as those chips are not that
          > > large compared to DSLR's and other APS-sized chips.
          > >
          > > Hope this helps,
          > > Wade Van Arsdale
          > > Little Rock, AR., USA
          > >
          > > --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@> wrote:
          > > >
          > > > Hi all. I have recently been working with a DSI II Pro CCD on an LX90 10 inch ACF which is collimated perfectly for visual observing. In most of my images, the brighter stars seem to have 2 projections coming off of them. When you overexpose the f/3 reduced pic, all the stars have this coming out from the center of pic. I am using a focal reducer and have had problems with focusing down to an f/3 which is what this picture was taken in, I use a botinov mask to focus. If anyone has seen this type problem, please let me know what it is. In a lot of my f/5 pics this is not as much an issue, except with the brighter stars on the periphery of the pic. I did have some periphery stars making smudges, but found out my IR filter was fogging up and was able to correct by wrapping a dew heater around the camera spacer.
          > > >
          > > > http://groups.yahoo.com/group/ccd-newastro/photos/album/771948104/pic/1434629078/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
          > > >
          > > > Thank You,
          > > >
          > > > Mark.
          > > >
          > >
          >
        • sforster12
          Keith, There has been a lot of discussion Re: a dedicated FF for the TMB 130SS scope. Rather than reinventing the wheel, how large a useful image circle do you
          Message 4 of 19 , Oct 8, 2009
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            Keith,

            There has been a lot of discussion Re: a dedicated FF for the TMB 130SS scope.

            Rather than reinventing the wheel, how large a useful image circle do you estimate the 27TVPH reducer gives?

            This would be a lot cheaper than having a new reducer developed, if most folks don't have monster sized chips.

            I just got an AP endpiece for my TMB 130SS so I can try my 27TVPH, but it will probably be spring before I give it a whirl with an ST-8.

            STU

            --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@...> wrote:
            >
            > Thanks for the additional info, Keith. That's good to know the
            > CCD67 f.r. works too with the Meade ACF SCT's on small-to-medium chip
            > cameras. We had not tested that one, only the 27TVPH. It makes
            > sense both f.r.'s would work with a scope that is fairly well "flat"
            > in field curvature. Both of those f.r.'s were designed for flat
            > fields with little curvature. Hopefully those two f.r.'s will also
            > perform well on the new Celestron flat-field SCT's too. AP is now
            > offering a visual back adapter for the 27TVPH that fits the Celestron
            > C14 and C11 OTA's.
            >
            > Thanks again for the help.
            >
            > Cheers,
            > Wade
            >
            > --- In ccd-newastro@yahoogroups.com, "Keith" <keith.myers@> wrote:
            > >
            > > I will recommend the AP focal reducers for ACF systems with small to medium size chips also. I have both 27TVPH and CCD67 reducers and they work wonderfully well with my ST-2K camera. Different story with the STL-11K. The .67X form factor is too small to fully illuminate the 35mm film format size of the STL. The .75X reducer does a much better job and only fails in the last 10% of the frame's corners. I have not tested the .75X with a DSLR however. Because the APS-C format is slightly smaller than full frame 35mm, you might get away with acceptably small coma in the corners.
            > >
            > > Keith
            > >
            > >
            > > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
            > > >
            > > > Hi Mark,
            > > > Re. the Meade focal reducer on ACF systems, the Meade f.r.'s
            > > > (and Celestron's too) have a "negative coma" designed into their
            > > > lens elements to correct for the inherent coma in their older SCT's
            > > > with the older optical prescription. This negative coma was the
            > > > same amount as the optical train, just with opposite curvature to
            > > > cancel the coma out.
            > > >
            > > > But when Meade came out with the new ACF design, the optical
            > > > prescription was different (flatter), so the focal reducer's own
            > > > optical prescription was no longer a match for that system. Note,
            > > > Celestron will now have the same problem with their new flat-field
            > > > SCT's they have just announced.
            > > >
            > > > So the problem is you have to use a focal reducer that is designed
            > > > for optical systems that are very "flat" (with little to no inherent
            > > > field curvature). As far as I know, neither Meade nor Celestron
            > > > offer such a f.r. (yet).
            > > >
            > > > You might consider the 27TVPH f.r. from Astro-Physics:
            > > > http://tinyurl.com/2pbnys
            > > >
            > > > You'll also need their ADASCTLM27 visual back adapter for your Meade:
            > > > http://tinyurl.com/2uftd4
            > > >
            > > > Be aware also, that you will not be reducing the focal length much
            > > > at all with this focal reducer. Here is a link to the focal
            > > > reducer's optical characteristics:
            > > > http://tinyurl.com/63qetp
            > > >
            > > > If back-focus is a concern, this page will help you calculate it:
            > > > http://www.wilmslowastro.com/software/formulae.htm#FR
            > > >
            > > > The correct chip-to-edge of f.r. body distance is 118mm for 0.75x
            > > > focal reduction. For more focal reduction, move this distance
            > > > outward with extra spacers, etc.... You can get spacers from AP
            > > > (check the above AP links).
            > > >
            > > > You can get a T-ring threaded cap here to mate this f.r. to
            > > > your camera:
            > > > http://www.rcopticalsystems.com/accessories/
            > > >
            > > > Just tell them you need the T-ring adapter with standard AP 2.7
            > > > inch threades (pic at bottom of above link).
            > > >
            > > > AP also has a clamping back-end adapter if your camera attaches
            > > > with a 2 inch nosepiece designed for focuser drawtubes (PN ADA2003):
            > > > http://tinyurl.com/3bsy6c
            > > >
            > > > You might also want to consider the CCDT67 focal reducer from
            > > > Astro-Physics as well:
            > > > http://tinyurl.com/yrjywn
            > > >
            > > > It is designed for systems of f/9 or longer and might work for
            > > > your Meade. I know for certain that the 27TVPH will work on Meade
            > > > ACF systems, because I worked with a Meade 14 inch ACF owner to
            > > > test the f.r. on that system. It produced round stars to the edges
            > > > of the field with an ST-2000XM camera. However, this camera only
            > > > requires a 15mm diameter image circle to cover the chip. Larger,
            > > > APS-sized chips (30mm image circle or larger) were not tested in
            > > > our sessions. So I don't know if the correction is as good with
            > > > those types of cameras. If you are using a Meade camera, it should
            > > > be fine though on field correction as those chips are not that
            > > > large compared to DSLR's and other APS-sized chips.
            > > >
            > > > Hope this helps,
            > > > Wade Van Arsdale
            > > > Little Rock, AR., USA
            > > >
            > > > --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@> wrote:
            > > > >
            > > > > Hi all. I have recently been working with a DSI II Pro CCD on an LX90 10 inch ACF which is collimated perfectly for visual observing. In most of my images, the brighter stars seem to have 2 projections coming off of them. When you overexpose the f/3 reduced pic, all the stars have this coming out from the center of pic. I am using a focal reducer and have had problems with focusing down to an f/3 which is what this picture was taken in, I use a botinov mask to focus. If anyone has seen this type problem, please let me know what it is. In a lot of my f/5 pics this is not as much an issue, except with the brighter stars on the periphery of the pic. I did have some periphery stars making smudges, but found out my IR filter was fogging up and was able to correct by wrapping a dew heater around the camera spacer.
            > > > >
            > > > > http://groups.yahoo.com/group/ccd-newastro/photos/album/771948104/pic/1434629078/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
            > > > >
            > > > > Thank You,
            > > > >
            > > > > Mark.
            > > > >
            > > >
            > >
            >
          • Wade Van Arsdale
            Stu, Not to jump Keith s answer, but at the recommended spacing of 118mm from end of focal reducer body to chip (0.75x focal reduction), the fully illuminated
            Message 5 of 19 , Oct 9, 2009
            • 0 Attachment
              Stu,
              Not to jump Keith's answer, but at the recommended spacing of
              118mm from end of focal reducer body to chip (0.75x focal reduction),
              the fully illuminated image circle is 42mm (as long as the scope
              can provide this size image circle too...the TMB 130SS more than
              likely does. Mike Bieler from Astronomics.com should be able to
              give you the spec on that hopefully, or you can measure the
              diameter directly at focal point behind the scope with a bright
              light source).

              The image circle size that the f.r. can deliver is derived from the
              f.r.'s clear aperature of 56mm x 0.75 focal reduction = 42mm. If you
              change spacing, multiply the 56mm value by the reduction factor,
              whatever it winds up being.

              See previous post for links to the AP article that explains in
              detail, and the link to a calculator tool for figuring the reduction
              factor vs. spacing distance.

              For your ST-8, that chip requires a 16.6mm diameter image circle
              to be fully illuminated. You should have no problem with vignetting
              on either of the two AP f.r.'s we mentioned.

              The best results in terms of star elongation/flat field for the TMB
              130SS scope would be from a *dedicated* focal reducer though. The
              TMB 130SS is going to have some field curvature on the edges.
              Since the two AP f.r.'s are totally flat in their optical design,
              neither reducer will be able to correct this. But with the chip size
              you will be using, it's not likely you would ever need a field
              flattener anyway. For example, my ST-2000 uses a 15mm image circle.
              I have never needed a field flattener with that camera on several
              different brands of refractors including TMB Optical, Stellarvue,
              Takahashi, and Orion. So I think you'll be fine on that with the
              ST-8. Where you'll start to see problems on field curvature are with
              the APS sized and above chips (around 30mm required image circle and
              larger).

              Cheers,
              Wade

              --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@...> wrote:
              >
              > Keith,
              >
              > There has been a lot of discussion Re: a dedicated FF for the TMB 130SS scope.
              >
              > Rather than reinventing the wheel, how large a useful image circle do you estimate the 27TVPH reducer gives?
              >
              > This would be a lot cheaper than having a new reducer developed, if most folks don't have monster sized chips.
              >
              > I just got an AP endpiece for my TMB 130SS so I can try my 27TVPH, but it will probably be spring before I give it a whirl with an ST-8.
              >
              > STU
              >
              > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
              > >
              > > Thanks for the additional info, Keith. That's good to know the
              > > CCD67 f.r. works too with the Meade ACF SCT's on small-to-medium chip
              > > cameras. We had not tested that one, only the 27TVPH. It makes
              > > sense both f.r.'s would work with a scope that is fairly well "flat"
              > > in field curvature. Both of those f.r.'s were designed for flat
              > > fields with little curvature. Hopefully those two f.r.'s will also
              > > perform well on the new Celestron flat-field SCT's too. AP is now
              > > offering a visual back adapter for the 27TVPH that fits the Celestron
              > > C14 and C11 OTA's.
              > >
              > > Thanks again for the help.
              > >
              > > Cheers,
              > > Wade
              > >
              > > --- In ccd-newastro@yahoogroups.com, "Keith" <keith.myers@> wrote:
              > > >
              > > > I will recommend the AP focal reducers for ACF systems with small to medium size chips also. I have both 27TVPH and CCD67 reducers and they work wonderfully well with my ST-2K camera. Different story with the STL-11K. The .67X form factor is too small to fully illuminate the 35mm film format size of the STL. The .75X reducer does a much better job and only fails in the last 10% of the frame's corners. I have not tested the .75X with a DSLR however. Because the APS-C format is slightly smaller than full frame 35mm, you might get away with acceptably small coma in the corners.
              > > >
              > > > Keith
              > > >
              > > >
              > > > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
              > > > >
              > > > > Hi Mark,
              > > > > Re. the Meade focal reducer on ACF systems, the Meade f.r.'s
              > > > > (and Celestron's too) have a "negative coma" designed into their
              > > > > lens elements to correct for the inherent coma in their older SCT's
              > > > > with the older optical prescription. This negative coma was the
              > > > > same amount as the optical train, just with opposite curvature to
              > > > > cancel the coma out.
              > > > >
              > > > > But when Meade came out with the new ACF design, the optical
              > > > > prescription was different (flatter), so the focal reducer's own
              > > > > optical prescription was no longer a match for that system. Note,
              > > > > Celestron will now have the same problem with their new flat-field
              > > > > SCT's they have just announced.
              > > > >
              > > > > So the problem is you have to use a focal reducer that is designed
              > > > > for optical systems that are very "flat" (with little to no inherent
              > > > > field curvature). As far as I know, neither Meade nor Celestron
              > > > > offer such a f.r. (yet).
              > > > >
              > > > > You might consider the 27TVPH f.r. from Astro-Physics:
              > > > > http://tinyurl.com/2pbnys
              > > > >
              > > > > You'll also need their ADASCTLM27 visual back adapter for your Meade:
              > > > > http://tinyurl.com/2uftd4
              > > > >
              > > > > Be aware also, that you will not be reducing the focal length much
              > > > > at all with this focal reducer. Here is a link to the focal
              > > > > reducer's optical characteristics:
              > > > > http://tinyurl.com/63qetp
              > > > >
              > > > > If back-focus is a concern, this page will help you calculate it:
              > > > > http://www.wilmslowastro.com/software/formulae.htm#FR
              > > > >
              > > > > The correct chip-to-edge of f.r. body distance is 118mm for 0.75x
              > > > > focal reduction. For more focal reduction, move this distance
              > > > > outward with extra spacers, etc.... You can get spacers from AP
              > > > > (check the above AP links).
              > > > >
              > > > > You can get a T-ring threaded cap here to mate this f.r. to
              > > > > your camera:
              > > > > http://www.rcopticalsystems.com/accessories/
              > > > >
              > > > > Just tell them you need the T-ring adapter with standard AP 2.7
              > > > > inch threades (pic at bottom of above link).
              > > > >
              > > > > AP also has a clamping back-end adapter if your camera attaches
              > > > > with a 2 inch nosepiece designed for focuser drawtubes (PN ADA2003):
              > > > > http://tinyurl.com/3bsy6c
              > > > >
              > > > > You might also want to consider the CCDT67 focal reducer from
              > > > > Astro-Physics as well:
              > > > > http://tinyurl.com/yrjywn
              > > > >
              > > > > It is designed for systems of f/9 or longer and might work for
              > > > > your Meade. I know for certain that the 27TVPH will work on Meade
              > > > > ACF systems, because I worked with a Meade 14 inch ACF owner to
              > > > > test the f.r. on that system. It produced round stars to the edges
              > > > > of the field with an ST-2000XM camera. However, this camera only
              > > > > requires a 15mm diameter image circle to cover the chip. Larger,
              > > > > APS-sized chips (30mm image circle or larger) were not tested in
              > > > > our sessions. So I don't know if the correction is as good with
              > > > > those types of cameras. If you are using a Meade camera, it should
              > > > > be fine though on field correction as those chips are not that
              > > > > large compared to DSLR's and other APS-sized chips.
              > > > >
              > > > > Hope this helps,
              > > > > Wade Van Arsdale
              > > > > Little Rock, AR., USA
              > > > >
              > > > > --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@> wrote:
              > > > > >
              > > > > > Hi all. I have recently been working with a DSI II Pro CCD on an LX90 10 inch ACF which is collimated perfectly for visual observing. In most of my images, the brighter stars seem to have 2 projections coming off of them. When you overexpose the f/3 reduced pic, all the stars have this coming out from the center of pic. I am using a focal reducer and have had problems with focusing down to an f/3 which is what this picture was taken in, I use a botinov mask to focus. If anyone has seen this type problem, please let me know what it is. In a lot of my f/5 pics this is not as much an issue, except with the brighter stars on the periphery of the pic. I did have some periphery stars making smudges, but found out my IR filter was fogging up and was able to correct by wrapping a dew heater around the camera spacer.
              > > > > >
              > > > > > http://groups.yahoo.com/group/ccd-newastro/photos/album/771948104/pic/1434629078/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
              > > > > >
              > > > > > Thank You,
              > > > > >
              > > > > > Mark.
              > > > > >
              > > > >
              > > >
              > >
              >
            • Wade Van Arsdale
              Stu, I noticed when reviewing the AP article from the earlier link, Roland *strongly* recommends the CCD67 focal reducer be used only on systems of f/9 or
              Message 6 of 19 , Oct 9, 2009
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                Stu, I noticed when reviewing the AP article from the earlier link,
                Roland *strongly* recommends the CCD67 focal reducer be used only
                on systems of f/9 or greater focal ratio. It does give a 30mm
                image circle at 0.67 focal reduction which will work fine with
                your camera, but it may not work well in other ways with the
                TMB130SS (back-focus, field curvature, etc...). The 27TVPH may be
                the better choice for the TMB 130SS. Keith can help you out there
                since he has real-life results from *both* f.r.'s.

                Also, before buying a f.r., you'll want to get the spec for
                available back-focus of the TMB 130SS. The 27TVPH f.r. will reduce
                the amount of available backfocus compared to native focus by around
                5-10mm at a chip spacing of 118mm to back edge of f.r. body on a
                focal ratio like the TMB 130SS has.

                It gets a little complicated with the 27TVPH f.r. when figuring
                out what backfocus the scope needs. The f.r. has a pretty handy
                design feature of mounting down inside the drawtube instead of
                protruding off the back-end of the focuser. This saves you 57mm of
                backfocus. This is already figured into the optimal spacing spec
                of 118mm to chip. (It would have been 175mm without this drawtube
                insert design feature).

                So in practical terms, whatever your scope provides in available
                back-focus, start at the optimal spacing from f.r. body to chip
                of 118mm, then add about 10mm more for optical reduction of native
                backfocus. So figure about 130-140mm of used-up backfocus for most
                camera configurations including filter wheel width, mating adapters,
                and spacer (if one is required). Most modern refractors have an
                available backfocus of 140-160mm or more, so this should work OK with
                the TMB 130SS, IIRC, but I would make sure with Mike just in case.
                The AP article at the earlier link should help clarify the
                calculations.

                PARTS MATRIX:
                If your scope has the FT 3.5 inch focuser, you'll need either the
                matching FT replacement "AP Endcap" for it (purchase the endcap from
                Starlight Instruments directly) to be able to use the 27TVPH
                f.r. I think the TMB130SS (at least some of them) use the FT 3.5
                inch focuser.

                I posted a folder earlier on the TMB SS group with all the parts
                matrix for the AP parts on the FT 3.5 inch focuser earlier including
                the T-Ring adapter to your camera. Hopefully the folder is still
                there.

                Cheers,
                Wade

                --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@...> wrote:
                >
                > Stu,
                > Not to jump Keith's answer, but at the recommended spacing of
                > 118mm from end of focal reducer body to chip (0.75x focal reduction),
                > the fully illuminated image circle is 42mm (as long as the scope
                > can provide this size image circle too...the TMB 130SS more than
                > likely does. Mike Bieler from Astronomics.com should be able to
                > give you the spec on that hopefully, or you can measure the
                > diameter directly at focal point behind the scope with a bright
                > light source).
                >
                > The image circle size that the f.r. can deliver is derived from the
                > f.r.'s clear aperature of 56mm x 0.75 focal reduction = 42mm. If you
                > change spacing, multiply the 56mm value by the reduction factor,
                > whatever it winds up being.
                >
                > See previous post for links to the AP article that explains in
                > detail, and the link to a calculator tool for figuring the reduction
                > factor vs. spacing distance.
                >
                > For your ST-8, that chip requires a 16.6mm diameter image circle
                > to be fully illuminated. You should have no problem with vignetting
                > on either of the two AP f.r.'s we mentioned.
                >
                > The best results in terms of star elongation/flat field for the TMB
                > 130SS scope would be from a *dedicated* focal reducer though. The
                > TMB 130SS is going to have some field curvature on the edges.
                > Since the two AP f.r.'s are totally flat in their optical design,
                > neither reducer will be able to correct this. But with the chip size
                > you will be using, it's not likely you would ever need a field
                > flattener anyway. For example, my ST-2000 uses a 15mm image circle.
                > I have never needed a field flattener with that camera on several
                > different brands of refractors including TMB Optical, Stellarvue,
                > Takahashi, and Orion. So I think you'll be fine on that with the
                > ST-8. Where you'll start to see problems on field curvature are with
                > the APS sized and above chips (around 30mm required image circle and
                > larger).
                >
                > Cheers,
                > Wade
                >
                > --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@> wrote:
                > >
                > > Keith,
                > >
                > > There has been a lot of discussion Re: a dedicated FF for the TMB 130SS scope.
                > >
                > > Rather than reinventing the wheel, how large a useful image circle do you estimate the 27TVPH reducer gives?
                > >
                > > This would be a lot cheaper than having a new reducer developed, if most folks don't have monster sized chips.
                > >
                > > I just got an AP endpiece for my TMB 130SS so I can try my 27TVPH, but it will probably be spring before I give it a whirl with an ST-8.
                > >
                > > STU
                > >
                > > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
                > > >
                > > > Thanks for the additional info, Keith. That's good to know the
                > > > CCD67 f.r. works too with the Meade ACF SCT's on small-to-medium chip
                > > > cameras. We had not tested that one, only the 27TVPH. It makes
                > > > sense both f.r.'s would work with a scope that is fairly well "flat"
                > > > in field curvature. Both of those f.r.'s were designed for flat
                > > > fields with little curvature. Hopefully those two f.r.'s will also
                > > > perform well on the new Celestron flat-field SCT's too. AP is now
                > > > offering a visual back adapter for the 27TVPH that fits the Celestron
                > > > C14 and C11 OTA's.
                > > >
                > > > Thanks again for the help.
                > > >
                > > > Cheers,
                > > > Wade
                > > >
                > > > --- In ccd-newastro@yahoogroups.com, "Keith" <keith.myers@> wrote:
                > > > >
                > > > > I will recommend the AP focal reducers for ACF systems with small to medium size chips also. I have both 27TVPH and CCD67 reducers and they work wonderfully well with my ST-2K camera. Different story with the STL-11K. The .67X form factor is too small to fully illuminate the 35mm film format size of the STL. The .75X reducer does a much better job and only fails in the last 10% of the frame's corners. I have not tested the .75X with a DSLR however. Because the APS-C format is slightly smaller than full frame 35mm, you might get away with acceptably small coma in the corners.
                > > > >
                > > > > Keith
                > > > >
                > > > >
                > > > > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
                > > > > >
                > > > > > Hi Mark,
                > > > > > Re. the Meade focal reducer on ACF systems, the Meade f.r.'s
                > > > > > (and Celestron's too) have a "negative coma" designed into their
                > > > > > lens elements to correct for the inherent coma in their older SCT's
                > > > > > with the older optical prescription. This negative coma was the
                > > > > > same amount as the optical train, just with opposite curvature to
                > > > > > cancel the coma out.
                > > > > >
                > > > > > But when Meade came out with the new ACF design, the optical
                > > > > > prescription was different (flatter), so the focal reducer's own
                > > > > > optical prescription was no longer a match for that system. Note,
                > > > > > Celestron will now have the same problem with their new flat-field
                > > > > > SCT's they have just announced.
                > > > > >
                > > > > > So the problem is you have to use a focal reducer that is designed
                > > > > > for optical systems that are very "flat" (with little to no inherent
                > > > > > field curvature). As far as I know, neither Meade nor Celestron
                > > > > > offer such a f.r. (yet).
                > > > > >
                > > > > > You might consider the 27TVPH f.r. from Astro-Physics:
                > > > > > http://tinyurl.com/2pbnys
                > > > > >
                > > > > > You'll also need their ADASCTLM27 visual back adapter for your Meade:
                > > > > > http://tinyurl.com/2uftd4
                > > > > >
                > > > > > Be aware also, that you will not be reducing the focal length much
                > > > > > at all with this focal reducer. Here is a link to the focal
                > > > > > reducer's optical characteristics:
                > > > > > http://tinyurl.com/63qetp
                > > > > >
                > > > > > If back-focus is a concern, this page will help you calculate it:
                > > > > > http://www.wilmslowastro.com/software/formulae.htm#FR
                > > > > >
                > > > > > The correct chip-to-edge of f.r. body distance is 118mm for 0.75x
                > > > > > focal reduction. For more focal reduction, move this distance
                > > > > > outward with extra spacers, etc.... You can get spacers from AP
                > > > > > (check the above AP links).
                > > > > >
                > > > > > You can get a T-ring threaded cap here to mate this f.r. to
                > > > > > your camera:
                > > > > > http://www.rcopticalsystems.com/accessories/
                > > > > >
                > > > > > Just tell them you need the T-ring adapter with standard AP 2.7
                > > > > > inch threades (pic at bottom of above link).
                > > > > >
                > > > > > AP also has a clamping back-end adapter if your camera attaches
                > > > > > with a 2 inch nosepiece designed for focuser drawtubes (PN ADA2003):
                > > > > > http://tinyurl.com/3bsy6c
                > > > > >
                > > > > > You might also want to consider the CCDT67 focal reducer from
                > > > > > Astro-Physics as well:
                > > > > > http://tinyurl.com/yrjywn
                > > > > >
                > > > > > It is designed for systems of f/9 or longer and might work for
                > > > > > your Meade. I know for certain that the 27TVPH will work on Meade
                > > > > > ACF systems, because I worked with a Meade 14 inch ACF owner to
                > > > > > test the f.r. on that system. It produced round stars to the edges
                > > > > > of the field with an ST-2000XM camera. However, this camera only
                > > > > > requires a 15mm diameter image circle to cover the chip. Larger,
                > > > > > APS-sized chips (30mm image circle or larger) were not tested in
                > > > > > our sessions. So I don't know if the correction is as good with
                > > > > > those types of cameras. If you are using a Meade camera, it should
                > > > > > be fine though on field correction as those chips are not that
                > > > > > large compared to DSLR's and other APS-sized chips.
                > > > > >
                > > > > > Hope this helps,
                > > > > > Wade Van Arsdale
                > > > > > Little Rock, AR., USA
                > > > > >
                > > > > > --- In ccd-newastro@yahoogroups.com, "MarkM" <denebola1973@> wrote:
                > > > > > >
                > > > > > > Hi all. I have recently been working with a DSI II Pro CCD on an LX90 10 inch ACF which is collimated perfectly for visual observing. In most of my images, the brighter stars seem to have 2 projections coming off of them. When you overexpose the f/3 reduced pic, all the stars have this coming out from the center of pic. I am using a focal reducer and have had problems with focusing down to an f/3 which is what this picture was taken in, I use a botinov mask to focus. If anyone has seen this type problem, please let me know what it is. In a lot of my f/5 pics this is not as much an issue, except with the brighter stars on the periphery of the pic. I did have some periphery stars making smudges, but found out my IR filter was fogging up and was able to correct by wrapping a dew heater around the camera spacer.
                > > > > > >
                > > > > > > http://groups.yahoo.com/group/ccd-newastro/photos/album/771948104/pic/1434629078/view?picmode=&mode=tn&order=ordinal&start=1&count=20&dir=asc
                > > > > > >
                > > > > > > Thank You,
                > > > > > >
                > > > > > > Mark.
                > > > > > >
                > > > > >
                > > > >
                > > >
                > >
                >
              • Keith
                Wade, yes it makes sense that any focal reducer/field flattener would have zero or near neutral correction at the very center of the field. Chips like the
                Message 7 of 19 , Oct 9, 2009
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                  Wade, yes it makes sense that any focal reducer/field flattener would have zero or near neutral correction at the very center of the field. Chips like the KAF-2020 used in the ST-2K are small enough that they chew out of the very central area of the light cone mostly and therefore experience minimal field curvature. Different story when you start getting 15-22 mm off-axis. The curvature then becomes very problematic with larger chips.

                  Keith


                  --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@...> wrote:
                  >
                  > Thanks for the additional info, Keith. That's good to know the
                  > CCD67 f.r. works too with the Meade ACF SCT's on small-to-medium chip
                  > cameras. We had not tested that one, only the 27TVPH. It makes
                  > sense both f.r.'s would work with a scope that is fairly well "flat"
                  > in field curvature. Both of those f.r.'s were designed for flat
                  > fields with little curvature. Hopefully those two f.r.'s will also
                  > perform well on the new Celestron flat-field SCT's too. AP is now
                  > offering a visual back adapter for the 27TVPH that fits the Celestron
                  > C14 and C11 OTA's.
                  >
                  > Thanks again for the help.
                  >
                  > Cheers,
                  > Wade
                • Keith
                  Stu, basically, exactly what Wade said. The AP docs do a good job explaining how to figure the maximum diameter of the illuminated image circle. The amount
                  Message 8 of 19 , Oct 9, 2009
                  • 0 Attachment
                    Stu, basically, exactly what Wade said. The AP docs do a good job explaining how to figure the maximum diameter of the illuminated image circle. The amount of curvature depends on the OTA's image circle as well as the size of the imaging chip. I'd say that with my Stellarvue SV152 refractor with AP 2.7" interface attachment to my STL-11K camera, the well corrected image circle of the 27TVPH is approximately 40mm out of the adapter's 42mm image circle at the specifieed 118mm spacing. As Wade has pointed out, the trick thing about the 27TVPPH is that with a 3" or 3.5" focuser interface, a good majority of the reducer goes up into the focuser drawtube and doesn't pull away from always limited back focus.

                    Now on another point....... I wasn't happy with the 27TVPH focal reducer on my STL-11K as previously mentioned. I wanted no coma at all in the entirety of my STL image frame. I do have to state that almost no one has negative comments on any of the images I have done with the SV152 and the STL. I just wanted perfection. I needed to only please myself. I have waited and watched and quested and searched for the 'phantom-ware' TMB 152 field flattener. I only have seen the one notice about its supposed creation at the $1600 price point but never saw one in the wild or heard that they ever actually existed. The SV152 uses the TMB152 optical cell. Then finally just this year earlier after another search, I stumbled upon a web comment and some pictures from an imager with the TMB152 with the 27TVPH on the STL and also with an AP 67PF582 field flattener. The 27TVPH was showing the same amount of coma I have experienced with the same equipment. The images with the AP field flattener however were coma free. I called AP and asked about the flattener and their response was 'of course we don't recommend this flattener for your scope, it's only designed for ours' The flattener is designed for a shorter FL than the TMB 152 optics, but I couldn't dispute the images created with it on the web. I decided to take a chance on it and was going to buy it, and it was going to be available from AP shortly but I lucked out and found a used one in excellent shape on Astro-Mart for half the price. So this summer I got a chance to check it out on the SV-152 and the STL-11K and was very nicely surprised that it works wonderfully at the longer FL than what it was designed for. You can check out the images taken with this set up here.

                    http://farm4.static.flickr.com/3484/3899490420_152bc29532_o.jpg
                    http://farm3.static.flickr.com/2516/3903317588_54abf93d03_o.jpg

                    Anyway, in this long roundabout discussion, I was going to recommend that you check out the AP field flatteners for the AP 130mm scope in the 2.7" interface with your TMB130SS refractor. The AP parts are expensive but very well built. And finally, I was trying to figure out how to use the new 2.5" field flattener from APM America. It is a generic flattener for F6-F9 scopes. The only drawback was its initial metric thread fastenings and no way to connect to the AP 2.7" system. They have been working on various adapters so that problem is solved. It's about half the price of the AP parts but I haven't seen a usage report from an owner yet, so it is still an unknown. I believe it to be a quality part however as the designers are from Germany with some TMB heritage I have been told.

                    Just my $0.02.

                    Keith

                    --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@...> wrote:
                    >
                    > Keith,
                    >
                    > There has been a lot of discussion Re: a dedicated FF for the TMB 130SS scope.
                    >
                    > Rather than reinventing the wheel, how large a useful image circle do you estimate the 27TVPH reducer gives?
                    >
                    > This would be a lot cheaper than having a new reducer developed, if most folks don't have monster sized chips.
                    >
                    > I just got an AP endpiece for my TMB 130SS so I can try my 27TVPH, but it will probably be spring before I give it a whirl with an ST-8.
                    >
                    > STU
                    >
                  • sforster12
                    Wade, I have both of the AP FR s that you are referring to and also have the AP endcap for the scope. What I don t have is enough free time or clear nights to
                    Message 9 of 19 , Oct 9, 2009
                    • 0 Attachment
                      Wade,

                      I have both of the AP FR's that you are referring to and also have the AP endcap for the scope.

                      What I don't have is enough free time or clear nights to try out the combos.

                      I'm waiting with bated breath for the beginning of another 120" snowfall winter.

                      It will probably be spring before I try it out.

                      STU



                      --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@...> wrote:
                      >
                      > Stu, I noticed when reviewing the AP article from the earlier link,
                      > Roland *strongly* recommends the CCD67 focal reducer be used only
                      > on systems of f/9 or greater focal ratio. It does give a 30mm
                      > image circle at 0.67 focal reduction which will work fine with
                      > your camera, but it may not work well in other ways with the
                      > TMB130SS (back-focus, field curvature, etc...). The 27TVPH may be
                      > the better choice for the TMB 130SS. Keith can help you out there
                      > since he has real-life results from *both* f.r.'s.
                      >
                      > Also, before buying a f.r., you'll want to get the spec for
                      > available back-focus of the TMB 130SS. The 27TVPH f.r. will reduce
                      > the amount of available backfocus compared to native focus by around
                      > 5-10mm at a chip spacing of 118mm to back edge of f.r. body on a
                      > focal ratio like the TMB 130SS has.
                      >
                      > It gets a little complicated with the 27TVPH f.r. when figuring
                      > out what backfocus the scope needs. The f.r. has a pretty handy
                      > design feature of mounting down inside the drawtube instead of
                      > protruding off the back-end of the focuser. This saves you 57mm of
                      > backfocus. This is already figured into the optimal spacing spec
                      > of 118mm to chip. (It would have been 175mm without this drawtube
                      > insert design feature).
                      >
                      > So in practical terms, whatever your scope provides in available
                      > back-focus, start at the optimal spacing from f.r. body to chip
                      > of 118mm, then add about 10mm more for optical reduction of native
                      > backfocus. So figure about 130-140mm of used-up backfocus for most
                      > camera configurations including filter wheel width, mating adapters,
                      > and spacer (if one is required). Most modern refractors have an
                      > available backfocus of 140-160mm or more, so this should work OK with
                      > the TMB 130SS, IIRC, but I would make sure with Mike just in case.
                      > The AP article at the earlier link should help clarify the
                      > calculations.
                      >
                      > PARTS MATRIX:
                      > If your scope has the FT 3.5 inch focuser, you'll need either the
                      > matching FT replacement "AP Endcap" for it (purchase the endcap from
                      > Starlight Instruments directly) to be able to use the 27TVPH
                      > f.r. I think the TMB130SS (at least some of them) use the FT 3.5
                      > inch focuser.
                      >
                      > I posted a folder earlier on the TMB SS group with all the parts
                      > matrix for the AP parts on the FT 3.5 inch focuser earlier including
                      > the T-Ring adapter to your camera. Hopefully the folder is still
                      > there.
                      >
                      > Cheers,
                      > Wade
                    • sforster12
                      I ve been following the thread about the 2.5 flattener, and the gent at APM America could not provide the info needs re: adapters when I was in contact with
                      Message 10 of 19 , Oct 9, 2009
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                        I've been following the thread about the 2.5" flattener, and the gent at APM America could not provide the info needs re: adapters when I was in contact with him a few months ago. To me it's still vaporware until the images appear.

                        I have a TMB 175 with an adapter to handle AP accessories, and if I'm going to spend on a dedicated FF, I'd go for the AP.

                        Roland had stated on a forum that a FF was designed for a particular radius of curvature. When I asked if the flattener for the 6" F-9 AP scope would work with a 7" F-8, he ducked the question.

                        I asked him in person this year at NEAF and he was a little more accomidating and made it sound like it would.

                        So I will try the AP 27TVPH on the TMB 130SS, and may look for an AP dedicated flattener for the 6" F-9.

                        STU
                      • Wade Van Arsdale
                        Good luck when you do get to it, Stu. I hope it works out. Cheers, Wade
                        Message 11 of 19 , Oct 9, 2009
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                          Good luck when you do get to it, Stu. I hope it works out.

                          Cheers,
                          Wade

                          --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@...> wrote:
                          >
                          > Wade,
                          >
                          > I have both of the AP FR's that you are referring to and also have the AP endcap for the scope.
                          >
                          > What I don't have is enough free time or clear nights to try out the combos.
                          >
                          > I'm waiting with bated breath for the beginning of another 120" snowfall winter.
                          >
                          > It will probably be spring before I try it out.
                          >
                          > STU
                          >
                          >
                          >
                          > --- In ccd-newastro@yahoogroups.com, "Wade Van Arsdale" <uwpf23@> wrote:
                          > >
                          > > Stu, I noticed when reviewing the AP article from the earlier link,
                          > > Roland *strongly* recommends the CCD67 focal reducer be used only
                          > > on systems of f/9 or greater focal ratio. It does give a 30mm
                          > > image circle at 0.67 focal reduction which will work fine with
                          > > your camera, but it may not work well in other ways with the
                          > > TMB130SS (back-focus, field curvature, etc...). The 27TVPH may be
                          > > the better choice for the TMB 130SS. Keith can help you out there
                          > > since he has real-life results from *both* f.r.'s.
                          > >
                          > > Also, before buying a f.r., you'll want to get the spec for
                          > > available back-focus of the TMB 130SS. The 27TVPH f.r. will reduce
                          > > the amount of available backfocus compared to native focus by around
                          > > 5-10mm at a chip spacing of 118mm to back edge of f.r. body on a
                          > > focal ratio like the TMB 130SS has.
                          > >
                          > > It gets a little complicated with the 27TVPH f.r. when figuring
                          > > out what backfocus the scope needs. The f.r. has a pretty handy
                          > > design feature of mounting down inside the drawtube instead of
                          > > protruding off the back-end of the focuser. This saves you 57mm of
                          > > backfocus. This is already figured into the optimal spacing spec
                          > > of 118mm to chip. (It would have been 175mm without this drawtube
                          > > insert design feature).
                          > >
                          > > So in practical terms, whatever your scope provides in available
                          > > back-focus, start at the optimal spacing from f.r. body to chip
                          > > of 118mm, then add about 10mm more for optical reduction of native
                          > > backfocus. So figure about 130-140mm of used-up backfocus for most
                          > > camera configurations including filter wheel width, mating adapters,
                          > > and spacer (if one is required). Most modern refractors have an
                          > > available backfocus of 140-160mm or more, so this should work OK with
                          > > the TMB 130SS, IIRC, but I would make sure with Mike just in case.
                          > > The AP article at the earlier link should help clarify the
                          > > calculations.
                          > >
                          > > PARTS MATRIX:
                          > > If your scope has the FT 3.5 inch focuser, you'll need either the
                          > > matching FT replacement "AP Endcap" for it (purchase the endcap from
                          > > Starlight Instruments directly) to be able to use the 27TVPH
                          > > f.r. I think the TMB130SS (at least some of them) use the FT 3.5
                          > > inch focuser.
                          > >
                          > > I posted a folder earlier on the TMB SS group with all the parts
                          > > matrix for the AP parts on the FT 3.5 inch focuser earlier including
                          > > the T-Ring adapter to your camera. Hopefully the folder is still
                          > > there.
                          > >
                          > > Cheers,
                          > > Wade
                          >
                        • Keith
                          Stu, not sure just what type of focuser your TMB130SS has. There are now adapters to go from the FeatherTouch 2.5 and 3.5 focusers to the telescope side of
                          Message 12 of 19 , Oct 10, 2009
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                            Stu, not sure just what type of focuser your TMB130SS has. There are now adapters to go from the FeatherTouch 2.5" and 3.5 focusers to the telescope side of the flattener. There is a adapter to go from the camera side to the STL camera too. So there is a APM America flattener solution for your STL-11K camera and the FeatherTouch focusers. If that is what is on the TMB as a caveat.

                            Keith

                            --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@...> wrote:
                            >
                            > I've been following the thread about the 2.5" flattener, and the gent at APM America could not provide the info needs re: adapters when I was in contact with him a few months ago. To me it's still vaporware until the images appear.
                            >
                            > I have a TMB 175 with an adapter to handle AP accessories, and if I'm going to spend on a dedicated FF, I'd go for the AP.
                            >
                            > Roland had stated on a forum that a FF was designed for a particular radius of curvature. When I asked if the flattener for the 6" F-9 AP scope would work with a 7" F-8, he ducked the question.
                            >
                            > I asked him in person this year at NEAF and he was a little more accomidating and made it sound like it would.
                            >
                            > So I will try the AP 27TVPH on the TMB 130SS, and may look for an AP dedicated flattener for the 6" F-9.
                            >
                            > STU
                            >
                          • sforster12
                            Keith, I have the Featherlight 3.5 on my 130SS, and just got the endcap that takes AP accessories. The gent at APM America could not guarantee that they had
                            Message 13 of 19 , Oct 11, 2009
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                              Keith,

                              I have the Featherlight 3.5" on my 130SS, and just got the endcap that takes AP accessories.

                              The gent at APM America could not guarantee that they had all the adapters/spacers to make their flattener work, but this was 3 months ago.

                              In addition, I have not seen a single image done with it.

                              I hate all the conjecture that goes along with these products.

                              If you put something on the market that costs a few hundred dollars, have a complete system that has been tested with proof.

                              STU

                              --- In ccd-newastro@yahoogroups.com, "Keith" <keith.myers@...> wrote:
                              >
                              > Stu, not sure just what type of focuser your TMB130SS has. There are now adapters to go from the FeatherTouch 2.5" and 3.5 focusers to the telescope side of the flattener. There is a adapter to go from the camera side to the STL camera too. So there is a APM America flattener solution for your STL-11K camera and the FeatherTouch focusers. If that is what is on the TMB as a caveat.
                              >
                              > Keith
                              >
                              > --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@> wrote:
                              > >
                              > > I've been following the thread about the 2.5" flattener, and the gent at APM America could not provide the info needs re: adapters when I was in contact with him a few months ago. To me it's still vaporware until the images appear.
                              > >
                              > > I have a TMB 175 with an adapter to handle AP accessories, and if I'm going to spend on a dedicated FF, I'd go for the AP.
                              > >
                              > > Roland had stated on a forum that a FF was designed for a particular radius of curvature. When I asked if the flattener for the 6" F-9 AP scope would work with a 7" F-8, he ducked the question.
                              > >
                              > > I asked him in person this year at NEAF and he was a little more accomidating and made it sound like it would.
                              > >
                              > > So I will try the AP 27TVPH on the TMB 130SS, and may look for an AP dedicated flattener for the 6" F-9.
                              > >
                              > > STU
                              > >
                              >
                            • Keith
                              Stu, I hear you. It unfortunate that the APM America site hasn t posted any pics using their 2.5 flattener. After all, the proof is in the picture. I was
                              Message 14 of 19 , Oct 12, 2009
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                                Stu, I hear you. It' unfortunate that the APM America site hasn't posted any pics using their 2.5" flattener. After all, the proof is in the picture. I was in the same boat with respect to the AP flattener. I sure wasn't going to throw $650 at the problem, sight unseen. It was just fantastic luck that I discovered someone else had already been the guinea pig. After I saw the simple JPEG's using the AP flattener, I felt comfortable in deciding to spend my money
                                I think it is a wise idea to pursue the AP flattener solutions now that you have the AP 2.7" interface.

                                Keith


                                --- In ccd-newastro@yahoogroups.com, "sforster12" <SHFORSTER1@...> wrote:
                                >
                                > Keith,
                                >
                                > I have the Featherlight 3.5" on my 130SS, and just got the endcap that takes AP accessories.
                                >
                                > The gent at APM America could not guarantee that they had all the adapters/spacers to make their flattener work, but this was 3 months ago.
                                >
                                > In addition, I have not seen a single image done with it.
                                >
                                > I hate all the conjecture that goes along with these products.
                                >
                                > If you put something on the market that costs a few hundred dollars, have a complete system that has been tested with proof.
                                >
                                > STU
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