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  1. #1
    william.lugg@cisf.af.mil's Avatar
    william.lugg@cisf.af.mil Guest

    Default Single Axis vs. Dual Axis drives



    We're looking at buying a telescope for our 13 year old son and are
    looking at drives. What are the pros and cons of the single and dual
    axis drives? What can you do with one that you can't with the other?
    We're looking at the EQ-3M drives from Orion.

    All thought are welcome.
    Bill Lugg


  2. #2
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default Single Axis vs. Dual Axis drives


    <william.lugg@cisf.af.mil> wrote in message
    news:1132987463.422401.322600@g47g2000cwa.googlegr oups.com...
    Think first about what you are doing, when you drive a scope, and when you
    'aim' a scope. If a scope is properly equatorial mounted, then to keep it
    pointing at one point in the sky, once 'aimed', as the Earth moves, all
    that is needed is a single motor, rotating it round the polar aligned
    axis, moving at the 'sidereal' rate. This is the classic 'single drive'
    configuration. However actually aiming the scope to centre an object,
    requires you to move the scope in both axes. So with the single drive, you
    have to take your hands off the 'controller' box, and aim the scope with
    the manual controls. The dual axis drives, make this easier, by allowing
    you not to touch the scope (with the vibration this introduces), and
    instead just hold the controller, and move the image in the eyepiece (or
    camera). The dual axis drives also allow you to do things like imaging,
    where you can use electronics to control the two axes (but this is beyond
    where you are working at present). In both cases, the maximum speeds of
    such drives are usually slow enough, that 'gross' re-alignment (pointing
    top a completely different part of the sky), is easier done with manual
    movements, but once you are close to the targte, the dual axis system,
    means you can keep your eye to the eyepiece, and shift an object more
    easily.
    No drives a all, means you have to be moving the scope all the time by
    hand.
    Single drive, means the scope will track to help keep an object centred.
    Dual drive, means you can centre the object in the first place, using the
    drives.

    Best Wishes



  3. #3
    Stephen Paul's Avatar
    Stephen Paul Guest

    Default Single Axis vs. Dual Axis drives


    "Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message
    news:XNVhf.6030$0o2.3142@newsfe3-gui.ntli.net...


    Is there a super cheap single drive solution for the GP/CG-5?

    So far I've come up with the Vixen MT-1/SD-1, the Celestron Dual, and the
    JMI 110VAC. I'm looking for something more akin to the Orion drive with the
    speed control. The one they make for the EQ-1 and EQ-2, without
    controller/corrector.

    Thanks,
    Stephen



  4. #4
    Chris L Peterson's Avatar
    Chris L Peterson Guest

    Default Single Axis vs. Dual Axis drives

    On 25 Nov 2005 22:44:23 -0800, william.lugg@cisf.af.mil wrote:


    As noted elsewhere, dual axis drives are a primary requirement for
    imaging. However, I like them also for visual use. That's because when I
    use a scope visually, I'm normally exploring. So I aim at a particular
    area, and then spend time sweeping it for interesting objects. Being
    able to control this kind of motion from a hand paddle is very
    convenient and comfortable. But to do this, your motors need to support
    at least 16X tracking, preferably more. Any slower and they are really
    only useful as guiding correctors- something that you don't need at all
    for visual use.

    _________________________________________________

    Chris L Peterson
    Cloudbait Observatory
    http://www.cloudbait.com

  5. #5
    tkuniok@calstatela.edu's Avatar
    tkuniok@calstatela.edu Guest

    Default Single Axis vs. Dual Axis drives

    william.lugg@cisf.af.mil wrote:

    I would say a dual axis control is particularly helpful at higher
    magnifications and when the observer can not simultaneously look
    through the eyepiece and reach the manual slow motion controls for the
    mount.

    At high magnifications, making the adjustments by slow motion controls
    introducing annoying vibrations. When you can't view and adjust
    simultaneously, then it's hard to center.

    Assuming that, in the real world, the polar alignment may be imperfect,
    having dual axis controls are nice. And I would suspect they are not
    that much different in price compared to the single axis drive.
    Zebra24601


  6. #6
    Stephen Paul's Avatar
    Stephen Paul Guest

    Default Single Axis vs. Dual Axis drives


    <tkuniok@calstatela.edu> wrote in message

    In fact, this is proving to be the case as I look around the web.

    Personally I'm just trying to avoid any wires on my CG-5 setup. If I could
    get an RA axis "logic" drive with the speed control potentiometer, I'd be
    happy as a clam. I'd then add a declination slow motion control. I'd rather
    spend a few minutes doing a reasonable job with rough polar alignment, than
    to have a wired hand paddle. As long as I can speed up or slow down to
    correct the RA, I don't mind making manual adjustments in Dec every now and
    then at the low powers I intend for the mounted scope.

    My other mount has dual digital drive, but I use that for imaging with an
    autoguider, and for observing with a larger scope at high power.

    Looks like Skywatcher might still have the single axis drive for the CG-5/GP
    with 4 D-Cells and a controller. But... if I'm already going to have a wire
    teathered controller, the additional wire and motor seem a small penalty,
    given the benefit and the small difference in price.

    Ah well...



 

 

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