Camera EXIF and focus distance

erich6erich6 Registered Users Posts: 1,638 Major grins
edited December 24, 2005 in Cameras
Does anyone know how to make sure the camera records the focus distance in the EXIF info?

I have a Canon 20D. Is this lens-dependent?

Erich

Comments

  • RichardRichard Administrators, Vanilla Admin Posts: 19,962 moderator
    edited December 21, 2005
    erich6 wrote:
    Does anyone know how to make sure the camera records the focus distance in the EXIF info?

    I have a Canon 20D. Is this lens-dependent?

    Erich
    I don't know of a way to control what the 20D records. A lot of what it does record goes into the Maker Notes section of the EXIF data. These fields are proprietary, so some software cannot decode them regardless of the lens you are using. I am guessing that you are talking about distance to subject, not focal length. The most complete information I have seen comes from a shareware program called EXIFutils, but I do not recall seeing distance to subject there, at least in any recognizable form. It's probably in there somewhere though. ne_nau.gif What program are you using to look at the data? Do you see the distance in some shots but not in others?

    Cheers,
  • erich6erich6 Registered Users Posts: 1,638 Major grins
    edited December 21, 2005
    Thanks for the reply.

    I'm using the Canon Zoombrowser that came with the camera. Yes, I'm looking for "distance to subject" (or more exactly "distance to focus point") not focal length.

    I use the DxO Optics Pro tool to correct for optical distortions and one of the parameters it uses as an input to determine the optimal correction is the "focus distance".

    Erich
  • JoeLJoeL Registered Users Posts: 158 Major grins
    edited December 21, 2005
    Theres a free program that you can use with PS and it works well.

    Heres the Link to the site, I use the EXIF program and the Filter
    program.

    http://www.opanda.com/en/index.html thumb.gif
  • OlgaJOlgaJ Registered Users Posts: 146 Major grins
    edited December 23, 2005
    erich6 wrote:
    Does anyone know how to make sure the camera records the focus distance in the EXIF info?

    I have a Canon 20D. Is this lens-dependent?

    Canon stopped putting the distance information in the EXIF starting with the 20D, I believe. I think that's because it wasn't all that accurate either.

    Olga
  • erich6erich6 Registered Users Posts: 1,638 Major grins
    edited December 23, 2005
    It appears to be the case...I checked out the EXIF utilities and the information was nowhere to be found. Too bad because I think that is an important piece of metadata.

    Erich
  • chuckhchuckh Registered Users Posts: 224 Major grins
    edited December 23, 2005
    erich6 wrote:
    It appears to be the case...I checked out the EXIF utilities and the information was nowhere to be found. Too bad because I think that is an important piece of metadata.

    Erich

    Perhaps now we know why there are so many reports of back/front focusing DSLR systems if Canon's AF algorithm doesn't know what the focus point distance is. :D

    (Just kidding)

    Is there an online source that describes the data structure of the EXIF data and it's offset location in a digital image file?
  • RichardRichard Administrators, Vanilla Admin Posts: 19,962 moderator
    edited December 24, 2005
    chuckh wrote:
    Is there an online source that describes the data structure of the EXIF data and it's offset location in a digital image file?
    Yep. Exif.org has the official specs online. It's not the lightest reading, so be warned.

    Cheers,
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