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Re: [ccd-newastro] Re: Focus setup for C11

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  • radiokx2l
    Sent from my Verizon Wireless 4G LTE Smartphone ... From: Orlando Andico Date: 08/28/2013 6:24 PM (GMT-07:00) To:
    Message 1 of 20 , Aug 28, 2013
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      Sent from my Verizon Wireless 4G LTE Smartphone

      -------- Original message --------
      From: Orlando Andico <orly.andico@...>
      Date: 08/28/2013 6:24 PM (GMT-07:00)
      To: ccd-newastro@yahoogroups.com
      Subject: Re: [ccd-newastro] Re: Focus setup for C11

      One issue with a Crayford focuser is that it adds back-focus, which
      lengthens the focal length.

      Granted the Crayford I was using on my C9.25 was not a Moonlite or
      Feathertouch, but a mere GSO. But I got rid of it and went back to the
      stock focuser (albeit with a Hutech locking knob). There is

      [Non-text portions of this message have been removed]
    • turnerjs085
      I eventually got tired of focusing my Meade 14 and got a moonlight with the motor. I already had a stepper motor focus controller from another scope and
      Message 2 of 20 , Aug 29, 2013
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        I eventually got tired of focusing my Meade 14" and got a moonlight with the motor. I already had a stepper motor focus controller from another scope and didn't have to buy that as well which helped with the cost. Still NOT cheap, but it just plain works. Push the button in FMax and it does its thing. The biggest improvement has been that with the time saved focusing, I can usually get 3-5 extra 1200sec subs a night. A good and consistent focuser is second only to the mount in importance in my experience.

        Does you mirror shift during an exposure, or just when focusing? Celestron's mirror support seems to be better than Meade's and doesn't always need to be locked during an exposure, as they usually suffer from fewer mirror flop problems.

        Jeremy

        --- In ccd-newastro@yahoogroups.com, "redmondjohn48" <jredmond17@...> wrote:
        >
        > Hello everyone,
        >
        > I have finally acknowledged defeat in trying to get good focus manually. I do have a feathertouch focuser for my C11 SCT, but I get a let of shift and shake, and, like others before me, find I waste a lot of time on a frequently unsucessful attempt to focus well enough for imaging. I read that one needs to immobilize the SCT mirror and focus instead with a crayford focuser inserted in the rear cell. Is this correct, and if so, any recommendationss as to product and way to hold the mirror?
        >
        > Thanks for your advice,
        >
        > John
        >
      • Tim Stone
        I use a bahtinov with out 17 planewave, and I get a better focus quicker that way than with our automated focus software. ... -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        Message 3 of 20 , Aug 29, 2013
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          I use a bahtinov with out 17" planewave, and I get a better focus quicker
          that way than with our automated focus software.

          On Thursday, August 29, 2013, Orlando Andico wrote:

          > **
          >
          >
          > i use a bahtinov mask on my C9.25
          >
          > it helps to get focus properly. but you can make do without it. it's
          > just faster with it.
          >
          > i don't have an auto-focuser so i can't say if a bahtinov mask is superior
          > to FWHM minimization via autofocusing. seems to work fine though.
          >
          > what i can say is the stars are almost always really bloated through the
          > C9.25 - but that would be the seeing.
          >
          > On Fri, Aug 30, 2013 at 12:01 AM, <stan_ccd@... <javascript:_e({},
          > 'cvml', 'stan_ccd%40yahoo.com');>> wrote:
          >
          > > **
          > >
          > >
          > > It takes some practice to master SCT primary mirror focusing. 1) use a
          > > Feathertouch adapter 2) always finish against gravity 3) find an
          > > exposure/display method that efficiently optimizes the task. I often use
          > > the vertical read-out spill lines from over-exposing a very bright star.
          > > For normal stars I enlarge the image 3x and scale it to primarily reveal
          > > brightness in the few central pixels. I am getting a Bahtinov mask and
          > > will let you know how it goes. The main culprit that frustrates focusing
          > > is seeing. Many nights fail to produce high certainty focus because there
          > > simply isn't one. As for stationary back-end focusers, they are pretty
          > > expensive, extend the back-focus distance (which can preclude or
          > > restrict reducers and such), and have limited carrying capacity. There is
          > > (was) a clever aftermarket secondary focuser that would be ideal, except
          > > that it cost $1k. Unfortunately I cannot locate it via Google/Bing, so
          > > maybe it is no longer available. Stan P.S. The Yahoo groups web UI
          > > has a new design and look but seems to lapse into the old one at random.
          > > --- In ccd-newastro@yahoogroups.com <javascript:_e({}, 'cvml',
          > 'ccd-newastro%40yahoogroups.com');>, <rwright@...> wrote: I went the
          > > Optec route too on a Celestron Edge HD 9.25. I just used the scopes
          > mirror
          > > lock to clamp it down, and then use the Optec for focusing. It's the only
          > > way to go.
          > >
          > > Richard
          > >
          > > On Aug 29, 2013, at 11:01 AM, "tpiccian" < tpicciani@... > wrote:
          > >
          > > > I did 2 things, one fairly cheap and one fairly expensive to help on my
          > > C9.25.
          > > >
          > > > The cheap item was a graduated disk that fit over the focus knob. They
          > > had them for multiple knob designs. But I can't connect to
          > > www.scopestuff.com anymore. Not sure if they're still around. Since the
          > > disk sits against the back of the scope, it prevents to some extent
          > > shifting or movement during focusing.
          > > >
          > > > The other expensive item was to buy a used 2 inch Optec TCF-S focuser,
          > > more for the fine zero shift movement than the temperature control.
          > > >
          > > > Tom P.
          > > >
          > > > --- In ccd-newastro@yahoogroups.com <javascript:_e({}, 'cvml',
          > 'ccd-newastro%40yahoogroups.com');> , "turnerjs085" <turnerjs085@...>
          > > wrote:
          > > > >
          > > > > I eventually got tired of focusing my Meade 14" and got a moonlight
          > > with the motor. I already had a stepper motor focus controller from
          > another
          > > scope and didn't have to buy that as well which helped with the cost.
          > Still
          > > NOT cheap, but it just plain works. Push the button in FMax and it does
          > its
          > > thing. The biggest improvement has been that with the time saved
          > focusing,
          > > I can usually get 3-5 extra 1200sec subs a night. A good and consistent
          > > focuser is second only to the mount in importance in my experience.
          > > > >
          > > > > Does you mirror shift during an exposure, or just when focusing?
          > > Celestron's mirror support seems to be better than Meade's and doesn't
          > > always need to be locked during an exposure, as they usually suffer from
          > > fewer mirror flop problems.
          > > > >
          > > > > Jeremy
          > > > >
          > > > > --- In ccd-newastro@yahoogroups.com <javascript:_e({}, 'cvml',
          > 'ccd-newastro%40yahoogroups.com');> , "redmondjohn48" <jredmond17@>
          > > wrote:
          > > > > >
          > > > > > Hello everyone,
          > > > > >
          > > > > > I have finally acknowledged defeat in trying to get good focus
          > > manually. I do have a feathertouch focuser for my C11 SCT, but I get a
          > let
          > > of shift and shake, and, like others before me, find I waste a lot of
          > time
          > > on a frequently unsucessful attempt to focus well enough for imaging. I
          > > read that one needs to immobilize the SCT mirror and focus instead with a
          > > crayford focuser inserted in the rear cell. Is this correct, and if so,
          > any
          > > recommendationss as to product and way to hold the mirror?
          > > > > >
          > > > > > Thanks for your advice,
          > > > > >
          > > > > > John
          > > > > >
          > > > >
          > > >
          > > >
          > >
          > >
          > >
          > > [Non-text portions of this message have been removed]
          > >
          > >
          > >
          >
          > --
          > Orlando Andico
          > +65.6436.1577 | +65.8139.0251
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >


          --
          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          Tim Stone


          [Non-text portions of this message have been removed]
        • CurtisC
          Automated focusing isn t about speed, it s about accuracy. Also, you don t have to be physically at the scope to focus it.
          Message 4 of 20 , Aug 29, 2013
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            Automated focusing isn't about speed, it's about accuracy. Also, you don't have to be physically at the scope to focus it.

            --- In ccd-newastro@yahoogroups.com, Tim Stone <tim.stone.piano@...> wrote:
            >
            > I use a bahtinov with out 17" planewave, and I get a better focus quicker
            > that way than with our automated focus software.
          • John Redmond
            The mirror shift is only noticeable when changing focus direction. I bought a micro touch focuser to drive my existing sct Starlight focuser since as Ron said,
            Message 5 of 20 , Sep 9, 2013
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              The mirror shift is only noticeable when changing focus direction.

              I bought a micro touch focuser to drive my existing sct Starlight focuser since as Ron said, it's worth a try, and I do have a hyperstar mod I can use with my C11. After a night or two with the motorized focus I can see its a time-saver, but it looks like the full benefit will be achieved only when I get a real ccd instead of a non-live view DSLR.

              I'm sure I'm not the only one to notice that this hobby tends to lure one into one expensive purchase after another!

              Impecuniously yours,

              John

              Sent from my iPad
            • tpiccian
              There is also an oversized vernier focus knob that fits over the rubber coated focus knob. If the C11 uses that type, which is what is on my C9.25, then it too
              Message 6 of 20 , Sep 10, 2013
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                There is also an oversized vernier focus knob that fits over the rubber coated focus knob. If the C11 uses that type, which is what is on my C9.25, then it too can help with focus shift. It's available at scopestuff.com. http://www.scopestuff.com/ss_foc9.htm



                --- In ccd-newastro@yahoogroups.com, <ccd-newastro@yahoogroups.com> wrote:

                The mirror shift is only noticeable when changing focus direction.

                I bought a micro touch focuser to drive my existing sct Starlight focuser since as Ron said, it's worth a try, and I do have a hyperstar mod I can use with my C11. After a night or two with the motorized focus I can see its a time-saver, but it looks like the full benefit will be achieved only when I get a real ccd instead of a non-live view DSLR.

                I'm sure I'm not the only one to notice that this hobby tends to lure one into one expensive purchase after another!

                Impecuniously yours,

                John

                Sent from my iPad
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