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  1. #1
    David Randell's Avatar
    David Randell Guest

    Default 2" Orion helical focusser



    Hi everybody,

    I have what I believe is a old 2" Orion helical focusser. I was thinking of
    using it to replace a cheap 1.25" r&p focusser on my 10" f/5 Dob - and to
    think of it, I think that one is an Orion one too. Does anyone have any
    experiences of these particular helical focussers? The only thing that is
    concerning me a bit, is that when I tighten up the nylon locking screw until
    just holds, and then turn the tube it binds, then slackens - so something is
    asymmetric. Is this to be expected from what I think is a budget helical
    focusser?

    Regards,
    Dave Randell



  2. #2
    Rod Mollise's Avatar
    Rod Mollise Guest

    Default 2" Orion helical focusser

    >

    Hi:

    Yes, the Orion, like any other helical, in my opinion, is the work of
    hmmmm...could it be? SATAN!? ;-)

    As you might gather, I don't like helicals, never have. NO matter how
    well-made, I wind up sliding the eyepiece in and out to focus.



    Peace,
    Rod Mollise
    Author of _Choosing and Using a Schmidt Cassegrain Telescope_
    Like SCTs and MCTs?
    Check-out sct-user, the mailing list for CAT fanciers!
    Goto <http://members.aol.com/RMOLLISE/index.html>

  3. #3
    Pat Nealy's Avatar
    Pat Nealy Guest

    Default 2" Orion helical focusser

    Rod,

    I have used two helical focusers, both very usable, in their own way.
    The first was the helical on an 8" Portaball. It was easy to use and
    fairly precise. After a few outings, I was very precise with it. The
    second was an older Meade helical that could be coarse focused by simply
    sliding it in, and then fine focused helically(is that a word?). The EP
    was held in place by friction only. It was a simple, yet elegant
    arrangement.

    Pat

    Rod Mollise wrote:


  4. #4
    Rod Mollise's Avatar
    Rod Mollise Guest

    Default 2" Orion helical focusser

    > The EP

    Hi Pat:

    What can I say? Just not to my taste. For my money the best focuser out there
    vis-a-vis price vice performance? The JMI NGF DX3.

    Peace,
    Rod Mollise
    Author of _Choosing and Using a Schmidt Cassegrain Telescope_
    Like SCTs and MCTs?
    Check-out sct-user, the mailing list for CAT fanciers!
    Goto <http://members.aol.com/RMOLLISE/index.html>

  5. #5
    Alan W. Craft's Avatar
    Alan W. Craft Guest

    Default 2" Orion helical focusser

    On 12 Oct 2003 22:13:02 GMT, rmollise@aol.com (Rod Mollise) ...reflected:


    Precisely the one I'm having Parks incorporate into my custom 8" f/5
    Newtonian.


    Alan

  6. #6
    Jon Isaacs's Avatar
    Jon Isaacs Guest

    Default 2" Orion helical focusser

    >As you might gather, I don't like helicals, never have. NO matter how

    My experience as well. Never used a high end helical but when changing
    eyepieces it can require substantial movement, not easily done with a helical.
    And the modest helical Discovery focuser I used for a while was certainly no
    great find. Replaced it with a 1.25 RCF focuser which was quite superior and
    as a kit only about $60.

    jon

  7. #7
    Thad Floryan's Avatar
    Thad Floryan Guest

    Default 2" Orion helical focusser

    rmollise@aol.com (Rod Mollise) wrote in message news:<20031012171040.22268.00000202@mb-m29.aol.com>...

    A lot depends upon the scope and application. For example, my first several
    years using an SBIG STV in eFinder mode and attempting to focus by sliding
    the tube in and out was frustrating. Then I "found" one of the Borg helical
    focusers and, WOW!, can reset and redial to a fraction of a mm with ease; for
    this application there simply is no other choice than a helical focuser.

    Other "proper" applications of helical focusers include those using camera
    bodies for astrophotography.

    Something many people don't realize is that good helical focusers do NOT
    rotate (the EPs or whatever), they simply move in and out by twisting a band.

    Note, too, the SAFIX is also adjusted akin to how a helical focuser is used.

  8. #8
    Thad Floryan's Avatar
    Thad Floryan Guest

    Default 2" Orion helical focusser

    rmollise@aol.com (Rod Mollise) wrote in message news:<20031012181302.22313.00000222@mb-m29.aol.com>...

    Interesting; I thought you preferred SCTs over Newts. :-)

 

 

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