Does EXIF tell the focusing distance?

Discussion in 'Digital Cameras' started by Rodrigo C., Sep 2, 2004.

  1. Rodrigo C.

    Rodrigo C. Guest

    why it only tells the focal length of the lens, but no the focusing
    distance?

    Thanks
     
    Rodrigo C., Sep 2, 2004
    #1
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  2. For SLR it might be because the distance is not known.

    It might also be because the camera focus in zones.

    It might also be because it is not in EXIF.

    And it might be because they don't think anyone want it.


    /Roland
     
    Roland Karlsson, Sep 2, 2004
    #2
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  3. Rodrigo C.

    Alan Browne Guest

     
    Alan Browne, Sep 2, 2004
    #3
  4. Rodrigo C.

    Alan Browne Guest

    If the Focus is encoded in the lens (as well as the FL) then a
    calculation of focus plane distance can be done.

    Not all lenses (probably damned few) encode the actual focus
    setting, and so that is why it does not appear in the EXIF
    outputs. (It may be recorded in the file, but if your software
    doesn't look for it, it might not come out).

    http://it.jeita.or.jp/document/publica/standard/exif/english/Exife.pdf
    Has "subject distance" defined as tag 37382 0x9206 (in TIFF I
    believe, not sure if the same convention is used in JPG.)

    However, if the lens does not encode the FL, then the subject
    distance cannot be computed.

    Minolta (D) lenses do encode the focus setting as it is required
    for the flash distance integration. Other OEM's also have focus
    encoding in their lenses ... but not all them.

    (Zoom FL has been integrated for at 15 years and used by the
    flash to zoom the flash head and display effective flash range).

    Cheers,
    Alan
     
    Alan Browne, Sep 2, 2004
    #4
  5. Rodrigo C.

    Rodrigo C. Guest

    but at least my camera (Minolta S414) tells me the focusing distance when
    i'm in manual mode (in the LCD), so thats means that the camera in fact
    knows that distance and it could be written in the EXIF data.
    yes, may be.

    I understand, but i'm still thinking that you don't have to encode the focus
    setting if we consider what I said about the manual focusing mode (that many
    digital cams have, Canon G and S series, A60-70-80 etc..)

    Thank you for your answer
    Cheers, Rodrigo
     
    Rodrigo C., Sep 2, 2004
    #5
  6. Rodrigo C.

    Rodrigo C. Guest

    In my particular case, Minolta S414, but I've never seen an EXIF tag with
    the subject distance (and I've seen a lot of digital photos of many
    different cameras)
    Do you know any camera that actually have that tag? and very important too..
    any software that can read that tag?


    Rodrigo
     
    Rodrigo C., Sep 2, 2004
    #6
  7. Rodrigo C.

    S Lee Guest

    Jim Townsend choreographed a chorus line of high-kicking electrons to spell
    out:
    With my Canon EF lenses that record distance information, BreezeBrowser can
    display the focus distance in the EXIF information, but none of the other
    programs I use to edit pictures reads that particular tag...
     
    S Lee, Sep 3, 2004
    #7
  8. Rodrigo C.

    John Bean Guest

    Adobe Camera Raw interprets the Makernote during raw conversion and writes
    the information to the SubjectDistance EXIF tag of a resulting JPEG, or at
    least it does for the Minolta A2. The Minolta software doesn't do this as
    far as I can see, neither does the camera itself if you produce the JPEG
    in-camera.

    --
    John Bean

    Electricity is actually made up of extremely tiny particles called
    electrons, that you cannot see with the naked eye unless you have been
    drinking (Dave Barry)
     
    John Bean, Sep 3, 2004
    #8
  9. Rodrigo C.

    Steve B Guest

    My old Casio QV3000EX recorded the subject distance in its EXIF but my new
    Olympus C750 doesn't.
     
    Steve B, Sep 3, 2004
    #9
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