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  1. #1
    Malcolm Stewart's Avatar
    Malcolm Stewart Guest

    Default Mounting a 2" eyepiece in a 2" focusser - how ?



    I've just bought a 2" 30mm wide-angle eyepiece at Astrofest for my Helios
    200mm f5 Dobsonian, which claims to have a 2" capable focusser. So I
    removed the 1¼" adapter, and there's simply too much space between the tips
    of the clamp screws when fully screwed in, and the 2" eyepiece tube (which
    is very close to a true 2" diam.). Should there be some sort of sleeve?
    ~2 - 3mm thick ? Can't see anything suitable in the telescope supplier's
    catalogue, and wonder how others have solved the problem.

    Many thanks
    --
    M Stewart
    Milton Keynes, UK
    http://www.megalith.freeserve.co.uk/oddimage.htm



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

    Default Mounting a 2" eyepiece in a 2" focusser - how ?


    "Malcolm Stewart" <malcolm_stewart@megalith.freeserve.co.uk> wrote in
    message news:cu0rtg$mb4$1@news6.svr.pol.co.uk...
    Normally there is another sleeve supplied with the scope, and the 1.25"
    adapter, goes into this, not directly into the focusser sleeve. So you
    have a set of 'nested' parts, rather like the Russian dolls, and only
    remove the number of 'layers' you need. It is unusual to have the 1.25"
    adapter go directly to the larger size, since it means it becomes a 'non
    standard' part. Have another look at the 1.25" adapter, and see if there
    is another part still attached to it.

    Best Wishes



  3. #3
    Malcolm Stewart's Avatar
    Malcolm Stewart Guest

    Default Mounting a 2" eyepiece in a 2" focusser - how ?

    "Roger Hamlett" <rogerspamignored@ttelmah.demon.co.uk> wrote in message
    news:0LSMd.677$ZT3.296@newsfe2-win.ntli.net...

    The 1.25" adapter screws into a female thread which is inside a male thread
    onto which I can mount an SLR via a T mount (42mm over the threads). So it
    looks as though my 'scope is optimised for photography (of the moon ?).
    Re-using toilet roll holders is beginning to look closer than before!

    Cheers,
    --
    M Stewart
    Milton Keynes, UK
    http://www.megalith.freeserve.co.uk/oddimage.htm





  4. #4
    chris.b@mail.dk's Avatar
    chris.b@mail.dk Guest

    Default Mounting a 2" eyepiece in a 2" focusser - how ?

    Cardboard isn't very practical. A bit of 2" plumbing pipe might work. I
    made a simple 2" focusser out of PVC a few years ago. Can't remember
    the actual dimensions now but it involved standard 2" PVC pipe and
    joints solvent-welded together. 2" eyepieces fitted it nicely.
    Be careful you don't drop anything straight through the focussing mount
    and down into the OTA! Either work with the scope horizontal or cover
    the primary mirror securely.

    Regards
    Chris.B


  5. #5
    Jim Easterbrook's Avatar
    Jim Easterbrook Guest

    Default Mounting a 2" eyepiece in a 2" focusser - how ?

    "Malcolm Stewart" <malcolm_stewart@megalith.freeserve.co.uk> wrote in
    news:cu0urh$on2$1@news6.svr.pol.co.uk:


    This 2 part 1.25" eyepiece holder is just what I have on my Dob. You
    should also have a 1-part 2" eyepiece holder of similar height to the
    1.25" holder and with the same base (over 2" diameter) that the focuser
    clamp screws hold onto. This is not a standard size, as far as I know, so
    you really need the right part. I don't know where you'd get one.
    --
    Jim Easterbrook <http://astro.jim-easterbrook.me.uk/>
    N51.36 W0.25

  6. #6
    Roger Hamlett's Avatar
    Roger Hamlett Guest

    Default Mounting a 2" eyepiece in a 2" focusser - how ?


    "Malcolm Stewart" <malcolm_stewart@megalith.freeserve.co.uk> wrote in
    message news:cu0urh$on2$1@news6.svr.pol.co.uk...
    If you have the ability to measure the bore diameter of the outer tube
    accurately, then I'll turn you a sleeve to fit. I'd suspect it may be
    2.160", which is the size used on the Orion Optics scopes inside the
    focussers. It really sounds as if you have one tube missing. The part you
    need, will have a 'rim', with a clamp screw, allowing the eyepiece to be
    clamped.

    Best Wishes




 

 

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