Diopter and focusing issue

Discussion in 'Digital Photography' started by Ron, May 20, 2005.

  1. Ron

    Ron Guest

    I'd been having some sharpness or perhaps focusing problems with my
    Oly E-300 and relatively short focal length lenses --- eg. OM 50 mm 1.8,
    and Kiron and Tokina wide angles with K adapter, all of which require
    pretty fine focusing wide open because of very narrow DOF. Unlike my
    old Pentax slr, the 300's viewfinder is a bit on the dark side, making
    focusing
    a tad less than ideal in the low light situations where I want to use these
    lenses.

    No problems with K mount telephotos and kit lens. As a bit of a test I
    rotated my diopter slightly (I have a pretty hefty perscription) and
    though what I could see appeared about as before I now found
    that the sharpness problems seem to have
    diminished. Obviously I was seeing a bit more precisely, though
    consciously I probably wouldn't have noticed. Has anyone else had this
    experience? Are there tolerances that need to be thought about very
    carefully? Other issues related to glasses? Instruction manuals seem
    to say little.

    Oh, and no beer before focusing and viewing in either case!
     
    Ron, May 20, 2005
    #1
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  2. "Ron" <> wrote:
    >
    > No problems with K mount telephotos and kit lens. As a bit of a test I
    > rotated my diopter slightly (I have a pretty hefty perscription) and
    > though what I could see appeared about as before I now found
    > that the sharpness problems seem to have
    > diminished. Obviously I was seeing a bit more precisely, though
    > consciously I probably wouldn't have noticed. Has anyone else had this
    > experience?


    Yes. The diopter has to be adjusted. If there are marks on the screen, one
    approach is to adjust the diopter until they are as sharp and clear to your
    eye as possible. (This _may_ be problematic in that if the marks are on the
    top surface of the screen, you really should adjust the diopter so that the
    focusing surface is optimally sharp. Look through the camera with the lens
    focused (by AF) on something with detail and adjust the diopter to make the
    image as sharp/clear as possible. But I find it easier to use marks on the
    screen to adjust the diopter.)

    > Are there tolerances that need to be thought about very
    > carefully? Other issues related to glasses?


    Your glasses will have different optical properties in different parts of
    the lens, so try to always place exactly the same part of the glasses lens
    over the viewfinder.

    David J. Littleboy
    Tokyo, Japan
     
    David J. Littleboy, May 20, 2005
    #2
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  3. Ron

    RK Guest

    David:

    Thank you. Very helpful.

    /r


    David J. Littleboy wrote:
    > "Ron" <> wrote:
     
    RK, May 21, 2005
    #3
  4. Ron

    Tony Guest

    I found one very good aid to macro focusing is a good high power narrow beam
    flashlight - preferably on a gooseneck to keep it pointed at the subject but
    I've done it hand held too. This gives a lot of light in the critical area
    but is not strong enough to have an effect on the strobe.
    If you are not using a focus rail for macro - I would suggest that too.
    If you are asking about doing macro in the field with live subjects -
    never mind any of my advice - things happen too quickly.

    --
    http://www.chapelhillnoir.com
    home of The Camera-ist's Manifesto
    The Improved Links Pages are at
    http://www.chapelhillnoir.com/links/mlinks00.html
    A sample chapter from "Haight-Ashbury" is at
    http://www.chapelhillnoir.com/writ/hait/hatitl.html

    "Ron" <> wrote in message
    news:6hoje.6058$...
    > I'd been having some sharpness or perhaps focusing problems with my
    > Oly E-300 and relatively short focal length lenses --- eg. OM 50 mm 1.8,
    > and Kiron and Tokina wide angles with K adapter, all of which require
    > pretty fine focusing wide open because of very narrow DOF. Unlike my
    > old Pentax slr, the 300's viewfinder is a bit on the dark side, making
    > focusing
    > a tad less than ideal in the low light situations where I want to use

    these
    > lenses.
    >
    > No problems with K mount telephotos and kit lens. As a bit of a test I
    > rotated my diopter slightly (I have a pretty hefty perscription) and
    > though what I could see appeared about as before I now found
    > that the sharpness problems seem to have
    > diminished. Obviously I was seeing a bit more precisely, though
    > consciously I probably wouldn't have noticed. Has anyone else had this
    > experience? Are there tolerances that need to be thought about very
    > carefully? Other issues related to glasses? Instruction manuals seem
    > to say little.
    >
    > Oh, and no beer before focusing and viewing in either case!
    >
     
    Tony, May 21, 2005
    #4
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