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  1. #1
    justbeats's Avatar
    justbeats Guest

    Default LX200 - best solution to "perfect" tracking



    My 10" LX200 Classic has great optics, but not-so-good tracking
    (despite many, many hours of tuning, balancing and PEC training). I had
    intended to fix the tracking problem by upgrading to a 14" LX200 GPS,
    but have decided not to do this now.

    Briefly, the reason is that having seen what I can achieve with a CCD
    and an 80mm ED (piggy-backed on the SCT), I believe there is loads of
    mileage in the 10" optics that is only compromised (at the moment) by
    the tracking problems. Also, my average seeing leaves VERY few nights
    where I could take advantage of the extra aperture, so it would just be
    lots of $ for little improvement in practice.

    So, hopefully at a lower cost, I intend to improve the tracking only
    (scope is pier mounted on a wedge in an observatory). What are my best
    options? I see gear upgrade kits are available, and many alternative
    mounts too. Not sure which way to go...

    Given a budget up to (say) £2K - how can I get my LX200 Classic
    pointing at a deep sky object for hours? Currently, I'm lucky to get a
    minute before lumps and bumps in the gears (or other tracking problems)
    spoil the images.

    Suggestions and (best of all) first hand experiences solicited.
    Cheers
    Beats


  2. #2
    RichA's Avatar
    RichA Guest

    Default LX200 - best solution to "perfect" tracking

    On 28 Jan 2005 00:30:28 -0800, "justbeats" <steve_beats@hotmail.com>
    wrote:


    Get a custom set of gears made for it. The electronics should be
    fine.
    -Rich

  3. #3
    HAVRILIAK's Avatar
    HAVRILIAK Guest

    Default LX200 - best solution to "perfect" tracking

    >I'm lucky to get a

    Lumps and bumps in the gear train are problems discussed in the Losmandy
    google discussion group. Basically the gears are lapped into matching sets
    with the use of diamond dust suspended in greese. This sounds complicated but
    it isn't. By the way, precision sets of gears are always lapped prior to
    installation.

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

    Default LX200 - best solution to "perfect" tracking

    On 28 Jan 2005 00:30:28 -0800, "justbeats" <steve_beats@hotmail.com>
    wrote:


    There is only one way to get close to perfect tracking on a budget, and
    that is to take the mount out of the equation. You do that by correcting
    the tracking in the optical train. Right now the only way to do that is
    with an AO7. If your CCD is a dual-sensor SBIG, you can add the AO7 and
    stay well inside your budget. If not, maybe you can do so by trading in
    your current camera.

    Otherwise, you options are to tune up the mount- lap or replace the
    gears, and definitely replace the bearings if your LX200 was made while
    Meade was still using plastic sleeve bearings (which was most of the
    life of the Classic models), or to replace the mount altogether. Here in
    the U.S. your budget would easily allow you to buy a G-11 + Gemini
    controller. Maybe not outside the U.S., though.

    _________________________________________________

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

  5. #5
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default LX200 - best solution to "perfect" tracking

    > "justbeats" <steve_beats@hotmail.com> wrote in message
    You don't mention what camera you have, but the ultimate 'fix', is the
    AO7. With this, the errors in the mount can be corrected better than any
    mechanical fix.

    I spent a lot of time and effort trying to get a LX200 to track well. I
    honed the gears, replaced parts of the gearset, re-aligned the system to
    get good orthogonality, etc. etc.. the biggest single improvement on the
    tracking, was a mirror lock (it is suprising just how much the image does
    shift as the mirror rolls round the baffle tube). At the end, the unit was
    useable, but not great. Putting the OTA, on a Losmandy G11, went further,
    but even this would not track for long without guider intervention. An
    AP900, finally got the tracking as I wanted it...
    That having all been said, an AO7, fitted to an identical LX200, provided
    there is a suitable guidestar, gives results that are as good, or better.

    Best Wishes



  6. #6
    justbeats's Avatar
    justbeats Guest

    Default LX200 - best solution to "perfect" tracking

    Useful feedback so far - thanks folks. Looks like a little extra
    information will help...

    I have a rudimentary "mirror lock" using a contraption through the
    shipping bolt hole. Works quite well to stop mirror flop. Not had much
    problem with that.

    My camera is SXV-H9 + guide head. I had intended to do guided exposures
    using the Orion 80ED as guide scope, but this can't react fast enough
    to the small errors in the drive system (which can't be PEC trained out
    entirely either). One minute (unguided) track and stack with multiple
    exposures is OK on the 80ED, because of the more forgiving image scale,
    but not satisfactory on the LX200, even with focal reducer (I usually
    get a tail on stars on 50% of images due to the aforementioned lumps
    and bumps in the drive train).

    I've seen the AO-7, it's not compatible with SXV (which I'm very
    pleased with), so I think I'd rather fix the mount.

    ticket...? Bearing in mind I was prepared to spend £6K+ on a 14"
    LX200, I could stretch the budget if it would really work...
    Cheers again
    Beats


  7. #7
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default LX200 - best solution to "perfect" tracking

    > "justbeats" <steve_beats@hotmail.com> wrote in message
    OK. The problem here is not that the guider can't respond quickly enough,
    but that the scope can't. You are accelerating/decelerating a heavy lump
    of metal, and this limits how qickly the guide corrections can be made.

    Wait a while.
    Starlight, are launching their own AO system. It is short (much shorter
    than the AO7, which adds a lot to the light path), and produces an
    'absolute' movement (so can be used with a seperate guide scope, or with a
    small OAG - they are offering a tiny OAG, to fit between the AO unit and
    the camera. Terry Platt has had a prototype running for some time, and is
    meant to be showing it at AstroFest in the UK next week. It might be worth
    waiting, and seeing if they announce a 'release date' at this show. :-)

    Your existing guider will work with the G11.
    The G11, does move much smoother than the LX200 ever manages. With the
    Gemini controller, it is possible to get very good movement, which is
    repeatable, and accurate. It also responds better to guide corrections,
    without the problems of the gearbox becoming unloaded on the LX200 (I
    presume you have got some extra weight on the East fork arm?). However, ou
    really must 'try' the handcontroller, before considering this controller.
    It is very much an 'acquired taste'. The lack of buttons means there is a
    complex menu structure, which on the latter software releases works well,
    but it is not necessarily to everybodies liking.

    Best Wishes



  8. #8
    justbeats's Avatar
    justbeats Guest

    Default LX200 - best solution to "perfect" tracking

    Yowza! I "Googled" to find out more about the prospective Starlight AO
    system you mention - and didn't find anything at all. Have I instigated
    a leaked "product announcement" here?!?!

    It isn't just inertia stopping guiding corrections - it's the time to
    expose/download the guide image too. I've got some very brief
    transients screwing things up. Too quick to correct, but slow enough to
    add tails to the brighter stars.

    An abilty to AO-adapt to images off a piggy-backed scope is new (to
    me), and really cool. This sounds right up my street (guide scope can
    point "elsewhere" for a bright guide star, while the AO system can
    quickly adapt the image hitting the CCD on the main scope)..

    Thanks for the tip. I'll wait! Wonder if Terry needs a beta tester...?


  9. #9
    Steve Sherman's Avatar
    Steve Sherman Guest

    Default LX200 - best solution to "perfect" tracking



    justbeats wrote:

    Lock the mirror and use a auto-guider. That will help, but will not
    make it perfect. There are no gears or motors that are perfect.
    Even dust on gear can cause a tracking error.

    Steve


  10. #10
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default LX200 - best solution to "perfect" tracking


    "justbeats" <steve_beats@hotmail.com> wrote in message
    news:1106958343.308120.102070@z14g2000cwz.googlegr oups.com...
    No, it has been discussed on the Starlight Express Yahoo group, for
    months, and there has even been a picture posted of it.
    It probably just hasn't had the 'keywords' right, to have hit Google yet.

    Seriously, with your USB camera, you should be able to take guide images
    of brighter stars, very quickly (actual magnitude depends on the scope
    used, but I have managed over 5fps, at F/6.1, on a C11, at Mag 9.5). The
    download time for the guide frame, is tiny. If you really have tiny 'fast'
    transients, that are quicker than perhaps 0.5 pixel/second, then these may
    well just be dust on your gears (or even metal filings). There were a
    number of cases of lumps of swarf in the main RA gear of the LX200 at
    various times. Cleaning, might help a lot. :-)


    Best Wishes



 

 
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