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Re: [lx90] Focusing

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  • Peter Vasey
    Hi, Hassan, Yes, it s quite disconcerting how the slightest touch can induce vibration at these longer focal lengths. There is very little you can do to
    Message 1 of 19 , May 8, 2013
      Hi, Hassan,

      Yes, it's quite disconcerting how the slightest touch can induce
      vibration at these longer focal lengths.

      There is very little you can do to increase the stiffness of your mount.
      Best solution is an electric focuser. There are a number of
      commercial offerings, the basic ones are reasonably priced, or you can
      go up market and get a computer controlled system.

      Or if you are reasonably handy, make your own. Many years ago I made
      one for my C8 using the geared motor from a broken electric wing mirror
      and a two way switch. Using an 'O' ring as a drive link I was able to
      coarse focus without problems, then use the electric one for the final
      touches. Worked a treat! See:
      http://www.madpc.co.uk/~peterv/astroplover/equipnbits/Kit/ELECFOCS.JPG

      You might be able to pick up an electric wing mirror from a scrapyard.

      Best of luck,

      Peter.

      http://www.madpc.co.uk/~peterv
      Approx. 55ºN, 2ºW (Northumberland, UK)

      On 08/05/2013 11:03, Hassan Boussi wrote:
      > I was trying to image using my 10" LX-90 and a DMK camera with a 2X barlow.
      > I noticed that when I tried to focus, it looked like an earthquake on the
      > screen from the vibration.
      >
      > What are the best options for focusing without creating this vibration?
      > Sorry for the dumb questions but I'm new to this and just learning.
      >
      >
      >
      > Many thanks.
      >
      >
      >
      > Hassan
    • Hassan Boussi
      The do-it-myself option is out of the equation as I don’t have the time to do that. I will look into the other options. Do you have any recommendations or
      Message 2 of 19 , May 9, 2013
        The do-it-myself option is out of the equation as I don’t have the time to
        do that. I will look into the other options. Do you have any recommendations
        or links?

        Many Thanks.

        Hassan



        From: lx90@yahoogroups.com [mailto:lx90@yahoogroups.com] On Behalf Of Peter
        Vasey
        Sent: Wednesday, May 08, 2013 9:13 AM
        To: lx90@yahoogroups.com
        Subject: Re: [lx90] Focusing





        Hi, Hassan,

        Yes, it's quite disconcerting how the slightest touch can induce
        vibration at these longer focal lengths.

        There is very little you can do to increase the stiffness of your mount.
        Best solution is an electric focuser. There are a number of
        commercial offerings, the basic ones are reasonably priced, or you can
        go up market and get a computer controlled system.

        Or if you are reasonably handy, make your own. Many years ago I made
        one for my C8 using the geared motor from a broken electric wing mirror
        and a two way switch. Using an 'O' ring as a drive link I was able to
        coarse focus without problems, then use the electric one for the final
        touches. Worked a treat! See:
        http://www.madpc.co.uk/~peterv/astroplover/equipnbits/Kit/ELECFOCS.JPG

        You might be able to pick up an electric wing mirror from a scrapyard.

        Best of luck,

        Peter.

        http://www.madpc.co.uk/~peterv
        Approx. 55ºN, 2ºW (Northumberland, UK)

        On 08/05/2013 11:03, Hassan Boussi wrote:
        > I was trying to image using my 10" LX-90 and a DMK camera with a 2X
        barlow.
        > I noticed that when I tried to focus, it looked like an earthquake on the
        > screen from the vibration.
        >
        > What are the best options for focusing without creating this vibration?
        > Sorry for the dumb questions but I'm new to this and just learning.
        >
        >
        >
        > Many thanks.
        >
        >
        >
        > Hassan





        [Non-text portions of this message have been removed]
      • Peter Vasey
        Hi, Hassan, Google search on electric focuser. Depending on what you want to do you can spend £100s. Anything from a simple add on to the existing focus
        Message 3 of 19 , May 9, 2013
          Hi, Hassan,

          Google search on electric focuser. Depending on what you want to do you
          can spend £100s. Anything from a simple add on to the existing focus
          knob to a fully fledged integrated Crayford focuser.

          But I've just remembered something I used to do with my LX90. A large
          sprung clothes peg clipped onto the focus knob gave fine control with
          minimal disturbance - once you are near focus just gently rotate using
          the tip of the peg.

          Something like this, wood or plastic, but wood has a higher coefficient
          of friction and will probably grip better:

          http://www.sxc.hu/pic/m/k/ki/kipcurry/517158_clothes_peg.jpg

          Worth a try and as near free as makes no difference ;-)

          Peter.

          http://www.madpc.co.uk/~peterv
          Approx. 55ºN, 2ºW (Northumberland, UK)

          On 09/05/2013 11:45, Hassan Boussi wrote:
          > The do-it-myself option is out of the equation as I don’t have the time to
          > do that. I will look into the other options. Do you have any recommendations
          > or links?
          >
          > Many Thanks.
          >
          > Hassan
          >
          >
          >
          > From: lx90@yahoogroups.com [mailto:lx90@yahoogroups.com] On Behalf Of Peter
          > Vasey
          > Sent: Wednesday, May 08, 2013 9:13 AM
          > To: lx90@yahoogroups.com
          > Subject: Re: [lx90] Focusing
          >
          >
          >
          >
          >
          > Hi, Hassan,
          >
          > Yes, it's quite disconcerting how the slightest touch can induce
          > vibration at these longer focal lengths.
          >
          > There is very little you can do to increase the stiffness of your mount.
          > Best solution is an electric focuser. There are a number of
          > commercial offerings, the basic ones are reasonably priced, or you can
          > go up market and get a computer controlled system.
          >
          > Or if you are reasonably handy, make your own. Many years ago I made
          > one for my C8 using the geared motor from a broken electric wing mirror
          > and a two way switch. Using an 'O' ring as a drive link I was able to
          > coarse focus without problems, then use the electric one for the final
          > touches. Worked a treat! See:
          > http://www.madpc.co.uk/~peterv/astroplover/equipnbits/Kit/ELECFOCS.JPG
          >
          > You might be able to pick up an electric wing mirror from a scrapyard.
          >
          > Best of luck,
          >
          > Peter.
          >
          > http://www.madpc.co.uk/~peterv
          > Approx. 55ºN, 2ºW (Northumberland, UK)
          >
          > On 08/05/2013 11:03, Hassan Boussi wrote:
          >> I was trying to image using my 10" LX-90 and a DMK camera with a 2X
          > barlow.
          >> I noticed that when I tried to focus, it looked like an earthquake on the
          >> screen from the vibration.
          >>
          >> What are the best options for focusing without creating this vibration?
          >> Sorry for the dumb questions but I'm new to this and just learning.
          >>
          >>
          >>
          >> Many thanks.
          >>
          >>
          >>
          >> Hassan
        • barringtonri
          What are you imaging that requires a 5000 mm focal length???? If you re attempting astronomical imaging focusing is going to be the least of your problems.
          Message 4 of 19 , May 9, 2013
            What are you imaging that requires a 5000 mm focal length???? If you're attempting astronomical imaging focusing is going to be the least of your problems.

            Lose the Barlow for starters. I also recommend ScopeStuff's inexpensive focusing knob http://www.scopestuff.com/ss_foc1.htm
            as a way to gently get a fine focus while hardly touching the scope.

            Clear skies,

            Pete Peterson
            Wishing Star Observatory

            --- In lx90@yahoogroups.com, "Hassan Boussi" <hassantb@...> wrote:
            >
            > I was trying to image using my 10" LX-90 and a DMK camera with a 2X barlow.
            > I noticed that when I tried to focus, it looked like an earthquake on the
            > screen from the vibration.
            >
            > What are the best options for focusing without creating this vibration?
            > Sorry for the dumb questions but I'm new to this and just learning.
            >
            >
            >
            > Many thanks.
            >
            >
            >
            > Hassan
            >
            >
            >
            > [Non-text portions of this message have been removed]
            >
          • Peter Vasey
            Hi, Pete, Have you never done any planetary imaging? Focal lengths of 6000 mm are quite common, for example an 8 SCT with 3x Barlow. Renowned planetary
            Message 5 of 19 , May 9, 2013
              Hi, Pete,

              Have you never done any planetary imaging? Focal lengths of 6000 mm are
              quite common, for example an 8" SCT with 3x Barlow. Renowned planetary
              imager Christopher Go uses a 2.5 x Barlow on a C14 - effective focal
              length of around 8800mm!

              You may have seen my earlier post where I suggest a clothes peg on the
              focus knob. A similar result to the Scopestuff and cheap as chips.

              Cheers,

              Peter.

              http://www.madpc.co.uk/~peterv
              Approx. 55ºN, 2ºW (Northumberland, UK)

              On 09/05/2013 14:39, barringtonri wrote:
              > What are you imaging that requires a 5000 mm focal length???? If you're attempting astronomical imaging focusing is going to be the least of your problems.
              >
              > Lose the Barlow for starters. I also recommend ScopeStuff's inexpensive focusing knob http://www.scopestuff.com/ss_foc1.htm
              > as a way to gently get a fine focus while hardly touching the scope.
              >
              > Clear skies,
              >
              > Pete Peterson
              > Wishing Star Observatory
              >
              > --- In lx90@yahoogroups.com, "Hassan Boussi"<hassantb@...> wrote:
              >>
              >> I was trying to image using my 10" LX-90 and a DMK camera with a 2X barlow.
              >> I noticed that when I tried to focus, it looked like an earthquake on the
              >> screen from the vibration.
              >>
              >> What are the best options for focusing without creating this vibration?
              >> Sorry for the dumb questions but I'm new to this and just learning.
              >>
              >>
              >>
              >> Many thanks.
              >>
              >>
              >>
              >> Hassan
            • barringtonri
              Sorry. Didn t realize that DMK as being a high speed video camera - best suited for planetary work. The only time I do lunar/planetary I m still using an old
              Message 6 of 19 , May 9, 2013
                Sorry. Didn't realize that DMK as being a high speed video camera - best suited for planetary work. The only time I do lunar/planetary I'm still using an old ToUcam

                Focusing is indeed super critical for planetary imaging, as is a long focal length. While the optimum solution is a motorized Crayford style focuser a bigger knob will go a long way toward obtaining a more delicate focus.

                Pete

                --- In lx90@yahoogroups.com, Peter Vasey <petevasey@...> wrote:
                >
                > Hi, Pete,
                >
                > Have you never done any planetary imaging? Focal lengths of 6000 mm are
                > quite common, for example an 8" SCT with 3x Barlow. Renowned planetary
                > imager Christopher Go uses a 2.5 x Barlow on a C14 - effective focal
                > length of around 8800mm!
                >
                > You may have seen my earlier post where I suggest a clothes peg on the
                > focus knob. A similar result to the Scopestuff and cheap as chips.
                >
                > Cheers,
                >
                > Peter.
                >
                > http://www.madpc.co.uk/~peterv
                > Approx. 55ºN, 2ºW (Northumberland, UK)
                >
                > On 09/05/2013 14:39, barringtonri wrote:
                > > What are you imaging that requires a 5000 mm focal length???? If you're attempting astronomical imaging focusing is going to be the least of your problems.
                > >
                > > Lose the Barlow for starters. I also recommend ScopeStuff's inexpensive focusing knob http://www.scopestuff.com/ss_foc1.htm
                > > as a way to gently get a fine focus while hardly touching the scope.
                > >
                > > Clear skies,
                > >
                > > Pete Peterson
                > > Wishing Star Observatory
                > >
                > > --- In lx90@yahoogroups.com, "Hassan Boussi"<hassantb@> wrote:
                > >>
                > >> I was trying to image using my 10" LX-90 and a DMK camera with a 2X barlow.
                > >> I noticed that when I tried to focus, it looked like an earthquake on the
                > >> screen from the vibration.
                > >>
                > >> What are the best options for focusing without creating this vibration?
                > >> Sorry for the dumb questions but I'm new to this and just learning.
                > >>
                > >>
                > >>
                > >> Many thanks.
                > >>
                > >>
                > >>
                > >> Hassan
                >
              • hassan
                As peter said, Saturn to be exact and it didnt fill up 25% of the window. I will try the clothes pin. Thank you. Hassan From my Android phone on T-Mobile. The
                Message 7 of 19 , May 9, 2013
                  As peter said, Saturn to be exact and it didnt fill up 25% of the window. I will try the clothes pin.
                  Thank you.
                  Hassan


                  From my Android phone on T-Mobile. The first nationwide 4G network.

                  -------- Original message --------
                  From: barringtonri <pecorp@...>
                  Date:
                  To: lx90@yahoogroups.com
                  Subject: [lx90] Re: Focusing

                  What are you imaging that requires a 5000 mm focal length???? If you're attempting astronomical imaging focusing is going to be the least of your problems.

                  Lose the Barlow for starters. I also recommend ScopeStuff's inexpensive focusing knob http://www.scopestuff.com/ss_foc1.htm
                  as a way to gently get a fine focus while hardly touching the scope.

                  Clear skies,

                  Pete Peterson
                  Wishing Star Observatory

                  --- In lx90@yahoogroups.com, "Hassan Boussi" <hassantb@...> wrote:
                  >
                  > I was trying to image using my 10" LX-90 and a DMK camera with a 2X barlow.
                  > I noticed that when I tried to focus, it looked like an earthquake on the
                  > screen from the vibration.
                  >
                  > What are the best options for focusing without creating this vibration?
                  > Sorry for the dumb questions but I'm new to this and just learning.
                  >
                  >
                  >
                  > Many thanks.
                  >
                  >
                  >
                  > Hassan
                  >
                  >
                  >
                  > [Non-text portions of this message have been removed]
                  >



                  [Non-text portions of this message have been removed]
                • adastra221
                  Hi Hassan, There really is no need to spend hard earned cash. As tasty alternative to Peter s suggestion (Hi Peter, long time no speaks) I used the top off a
                  Message 8 of 19 , May 10, 2013
                    Hi Hassan,

                    There really is no need to spend hard earned cash. As tasty alternative to Peter's suggestion (Hi Peter, long time no speaks) I used the top off a Marmite jar held in place with a grommet. This solution is almost identical to the ScopeStuff item, comes in easy to see Yellow, if using Marmite or Red if using Bovril, cost nothing and has worked for years :-)

                    Regards,

                    DaveE

                    [Non-text portions of this message have been removed]
                  • Iain
                    Hi DaveE, I now have the Marmite screw lid (Yellow) but dont see how to place it onto a Meade LK90. Any chanch of a photo or hints on how to put it all
                    Message 9 of 19 , May 11, 2013
                      Hi DaveE, I now have the Marmite screw lid (Yellow) but dont see how to place it
                      onto a Meade LK90. Any chanch of a photo or hints on how to put it all together ?

                      Iain
                      ZL1IW

                      [Non-text portions of this message have been removed]
                    • adastra221
                      Hi Iain, Sorry for the delay in replying. Make a hole in the centre of the lid to match the diameter of the focus knob into which you need to fit a standard
                      Message 10 of 19 , May 14, 2013
                        Hi Iain,

                        Sorry for the delay in replying.

                        Make a hole in the centre of the lid to match the diameter of the focus knob into which you need to fit a standard rubber gromet, i.e. of the type used to protect mains cables in a metal wall mounted electrical box. This provide a nice tight fit between the lid and the focus knob.
                        | | <-- Focus knob
                        ___::| |::___
                        |___::| |::___| <-- Marmite lid
                        ^-- Rubber gromet
                        You then use the existing knob for course focus and the outer edge of the marmite lid for your fine focus.

                        Regards,

                        DaveE

                        [Non-text portions of this message have been removed]
                      • adastra221
                        Hi Iain, The little diagram I posted is displayed slightly misaligned. You ll need to shift the top and bottom line to the right in your mind to align them
                        Message 11 of 19 , May 15, 2013
                          Hi Iain,

                          The little diagram I posted is displayed slightly misaligned. You'll need to shift the top and bottom line to the right in your mind to align them with the middle rows - if you follow?

                          Hope this clarifies things for you.
                          Clear Skies,
                          DaveE
                        • Iain
                          Hi Dave, Yeah I guessed things were a little off, but it did not take long to sort it out. Should be up and running, once the bad weather moves on Thanks Iain
                          Message 12 of 19 , May 18, 2013
                            Hi Dave, Yeah I guessed things were a little off, but it did not take long to sort it out.

                            Should be up and running, once the bad weather moves on

                            Thanks
                            Iain


                            [Non-text portions of this message have been removed]
                          • adastra221
                            Great stuff Iain, You ll have to let us know how you find usingcthe Marmite focuser - Once the word gets out it could start a run on Marmite in the superstores
                            Message 13 of 19 , May 18, 2013
                              Great stuff Iain,

                              You'll have to let us know how you find usingcthe Marmite focuser - Once the word gets out it could start a run on Marmite in the superstores ;-)

                              Ckear skies,
                              DaveE

                              [Non-text portions of this message have been removed]
                            • johnm
                              Re focusing aids On my L90 classic I have found that the bung that is used for end of walking sticks is a vast improvement on the metal cylinder focuser.
                              Message 14 of 19 , May 22, 2013
                                Re focusing aids

                                On my L90 classic I have found that "the bung" that is used for end of walking sticks is a vast improvement on the metal cylinder focuser. These bungs come in various diameters and I found one which is a nice tight fit and the cost is negligible.

                                John (Leeds UK)


                                --- In lx90@yahoogroups.com, <astrostar@...> wrote:
                                >
                                > Great stuff Iain,
                                >
                                > You'll have to let us know how you find usingcthe Marmite focuser - Once the word gets out it could start a run on Marmite in the superstores ;-)
                                >
                                > Ckear skies,
                                > DaveE
                                >
                                > [Non-text portions of this message have been removed]
                                >
                              • Doug Person
                                John, What a fabulous idea. Doug (Clark, CO US @ 8210 NW Rockies) ... [Non-text portions of this message have been removed]
                                Message 15 of 19 , May 22, 2013
                                  John,
                                  What a fabulous idea.
                                  Doug
                                  (Clark, CO US @ 8210' NW Rockies)

                                  On 5/22/2013 12:37 PM, johnm wrote:
                                  >
                                  > Re focusing aids
                                  >
                                  > On my L90 classic I have found that "the bung" that is used for end of
                                  > walking sticks is a vast improvement on the metal cylinder focuser.
                                  > These bungs come in various diameters and I found one which is a nice
                                  > tight fit and the cost is negligible.
                                  >
                                  > John (Leeds UK)
                                  >
                                  > --- In lx90@yahoogroups.com <mailto:lx90%40yahoogroups.com>,
                                  > <astrostar@...> wrote:
                                  > >
                                  > > Great stuff Iain,
                                  > >
                                  > > You'll have to let us know how you find usingcthe Marmite focuser -
                                  > Once the word gets out it could start a run on Marmite in the
                                  > superstores ;-)
                                  > >
                                  > > Ckear skies,
                                  > > DaveE
                                  > >
                                  > > [Non-text portions of this message have been removed]
                                  > >
                                  >
                                  >



                                  [Non-text portions of this message have been removed]
                                • Bart Trickel
                                  I used a wheel from a cloths drier. Its the wheel the drum rides on. It has a bronze bushing in the center, which I pressed out. There is a plastic hub with a
                                  Message 16 of 19 , May 22, 2013
                                    I used a wheel from a cloths drier.
                                    Its the wheel the drum rides on.
                                    It has a bronze bushing in the center, which I pressed out.
                                    There is a plastic hub with a rubber wheel on the outside.
                                    The plastic hub, without the bronze bushing, pressed right on the
                                    focusing knob of my lx90 8".
                                    The total diameter is a bit over 2".
                                    I use the old focuser for course focus and the wheel as fine focus.

                                    Bart


                                    "Only he who attempts the absurd
                                    is capable of achieving the impossible."
                                    Miguel de Unamuno





                                    On May 22, 2013, at 1:16 PM, Doug Person wrote:

                                    > John,
                                    > What a fabulous idea.
                                    > Doug
                                    > (Clark, CO US @ 8210' NW Rockies)
                                    >
                                    > On 5/22/2013 12:37 PM, johnm wrote:
                                    >>
                                    >> Re focusing aids
                                    >>
                                    >> On my L90 classic I have found that "the bung" that is used for end
                                    >> of
                                    >> walking sticks is a vast improvement on the metal cylinder focuser.
                                    >> These bungs come in various diameters and I found one which is a nice
                                    >> tight fit and the cost is negligible.
                                    >>
                                    >> John (Leeds UK)
                                    >>
                                    >> --- In lx90@yahoogroups.com <mailto:lx90%40yahoogroups.com>,
                                    >> <astrostar@...> wrote:
                                    >>>
                                    >>> Great stuff Iain,
                                    >>>
                                    >>> You'll have to let us know how you find usingcthe Marmite focuser -
                                    >> Once the word gets out it could start a run on Marmite in the
                                    >> superstores ;-)
                                    >>>
                                    >>> Ckear skies,
                                    >>> DaveE
                                    >>>
                                    >>> [Non-text portions of this message have been removed]
                                    >>>
                                    >>
                                    >>
                                    >
                                    >
                                    >
                                    > [Non-text portions of this message have been removed]
                                    >
                                    >
                                    >
                                    > ------------------------------------
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