Hyperfocal Distances

Discussion in 'Digital Cameras' started by Alan McGrath, Jun 5, 2006.

  1. Alan McGrath

    Alan McGrath Guest

    Hi,

    Does anyone have a way to set "today's" lenses to their hyperfocal distance?
    In the "old" days most lenses had a depth of field scale which enabled the
    user to easily set the hyperfocal distance. As far as I can see today's
    auto focus lenses have no such scale and therefore no visible way to set the
    hyperfocal distance. Am I wrong? Is there a 'trick" that can be used to
    accomplish this?

    Many thanks in advance for any constructive comments.

    Alan
     
    Alan McGrath, Jun 5, 2006
    #1
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  2. Fine link!
    By the way, beware that with a current dSLR you have to set the circle
    of confusion at the size of 1 pixel, or 2 if you take the AA filter and
    other things into account : that makes it around 10µm (0.010mm if you
    like zeros) on a 6-8µm pitch dSLR (eg RebelXT, 5D, 1Dsmk2...).
    The common 30µm CoC (the one of the example chart in the link) makes a
    _very_ noticeable blur on such cameras (as some had previously
    complained about with film, btw).

    See eg http://www.normankoren.com/Tutorials/MTF6.html for more (well
    funded) theory on the subject.

    ______________

    Thanks for that link! Tons of interesting stuff there, and at the linked
    page on lens testing too.
     
    John Falstaff, Jun 5, 2006
    #2
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  3. SNIP
    Is there a 'trick" that can be used to
    I don't recall any trick other than to use some tape and make your own
    empirically derived markings for certain apertures. However, that is
    going to be of little use if you start to enlarge your images beyond,
    say, a 5x7 inch or 8x10 (depending on the sensor size).

    Real DOF, which is based on the same circle of confusion (COC)
    concept, is very small with digital sensors, as another poster
    mentioned. As soon as the COC diameter hits more than a single pixel
    (or falls between two 'half' ones) multiple pixels will be affected
    and the results can be interpreted as blur.

    Another in-depth treatise of the underlying principles can be found
    at:
    <http://doug.kerr.home.att.net/pumpkin/Depth_of_Field.pdf>

    Bart
     
    Bart van der Wolf, Jun 5, 2006
    #3
  4. Alan McGrath

    secheese Guest

    "Focus your lens at infinity and the leading edge of the area that is
    in focus is the hyper focal point for that lens. Refocus on that point
    instead of infinity and you'll have the greatest range of focus from
    infinity back toward your location." Taken from:
    http://www.vividlight.com/articles/2314.htm
     
    secheese, Jun 5, 2006
    #4
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