Author Topic: Add Variables for certain EXIF information  (Read 6270 times)

Offline archer69

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Add Variables for certain EXIF information
« on: April 08, 2009, 12:07:46 PM »
Hi Kirk,

Using a Nikon D200/D300 I just learned that the camera in combination with CPU (D) lenses record certain focus distance information that would be nice to see. Would it be possible to create variables for the following EXIF data:

- Focus Distance
- Depth Of Focus
- Hyperfocal Distance

I admit I didn't search if it was requested before or if it's included in PM 4.6 (I'm still using 4.5.4).

Thanks,

Juerg
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Juerg H.
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Offline Hayo Baan

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Re: Add Variables for certain EXIF information
« Reply #1 on: April 09, 2009, 01:14:40 AM »
Hi Juerg,

To my knowledge, only Focus Distance is a value actually recorded inside the (encrypted) part of the "Nikon maker data." This value is currently not included in the application, perhaps it could be included. It will probably a Nikon specific value only though...

DOF and Hyperfocal Distance are calculated fields and are certainly not exact measures (even though there seem to be some "standards", the choice of the Circle of Confusion is very debatable). I therefore see the relevance of these values as very low.

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Offline archer69

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Re: Add Variables for certain EXIF information
« Reply #2 on: April 09, 2009, 08:08:55 AM »
Hi Juerg,

To my knowledge, only Focus Distance is a value actually recorded inside the (encrypted) part of the "Nikon maker data." This value is currently not included in the application, perhaps it could be included. It will probably a Nikon specific value only though...

Hayo,

I admit, I don't know anything about the 'Nikon Maker Data' and whether it's encrypted or not.
Of the three values listed, the 'Focus Distance' certainly is the most interesting one for me as well. But if I understand you right it may be Nikon specific and not easily implemented or at least not useful for non-Nikon users. Would be nice to have in any case.

Quote
DOF and Hyperfocal Distance are calculated fields and are certainly not exact measures (even though there seem to be some "standards", the choice of the Circle of Confusion is very debatable). I therefore see the relevance of these values as very low.

I realize that DOF and Hyperfocal Distance are calculated. And by having the focus distance, aperture and focal length I can use a free DOF calculator to do it. But as this is already done in camera it would be nice to read the data's out and have them available. Again, may be a lot of work and not useful for many.

Juerg
Regards,
Juerg H.
www.jh-photography.net

Offline vAfotoriporter

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Re: Add Variables for certain EXIF information
« Reply #3 on: April 11, 2009, 02:16:59 AM »
What good is it to know from an image what DOF it has? By my understanding of these numbers they are calculated BEFORE pressing the shutter release to allow you to compose the image you want to make. Having them afterwards is only a nice extra feature without any real value. Correct me if I'm wrong.
Working on Mac, OSX, iOS and with some Canons.
Allways shooting RAW.

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Offline platti

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Re: Add Variables for certain EXIF information
« Reply #4 on: April 11, 2009, 08:53:44 AM »
Hi,

just by the way: where is the distance saved in the exifs? Is it even saved? I don't find any item (Canon), that includes the distance of the object.
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Offline archer69

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Re: Add Variables for certain EXIF information
« Reply #5 on: April 12, 2009, 12:33:09 AM »
What good is it to know from an image what DOF it has? By my understanding of these numbers they are calculated BEFORE pressing the shutter release to allow you to compose the image you want to make. Having them afterwards is only a nice extra feature without any real value. Correct me if I'm wrong.

Well, for me it is an analysing tool and learning tool. I like it specifically for macro shots, but is helpful also in other situations. I agree, it would be nice to see it before shooting and would be much more helpful, but even after the fact it's nice. As I said, the important number would be the focus distance. DOF and Hyperfocal Distance would be nice to have if they are easily extracted, but can be calculate if you have the focus distance.

Quote from: platti
just by the way: where is the distance saved in the exifs? Is it even saved? I don't find any item (Canon), that includes the distance of the object.

Platti,

Unfortunately, on Nikon neither Nikon NX/NX2 nor Nikon View NX or Photoshop File Info show the focus distance. Also Opanda IExif 2.3 seems not to show it. But I downloaded the free KUSO EXIF Viewer V3.0(http://www.kuso.cc/exifviewer/) which shows much more EXIF information. Please note that the site is in Japanese (I believe), but about 3/4 down the page is the link to the English-version download.

You have to look at the data for one of your pictures and see whether the camera records focus length. My D200/D300 do (when used with a distance reporting lens). The D70 didn't. So it depends whether you find it on your Canons.

Juerg


« Last Edit: April 12, 2009, 12:34:43 AM by archer69 »
Regards,
Juerg H.
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Offline platti

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Re: Add Variables for certain EXIF information
« Reply #6 on: April 12, 2009, 01:47:30 AM »
Hi Jürg

I'm reading the exifs with the exiftool on a mac, my two canons (40D, 5D) do not contain distancetags. I get hyperfocaldistance, but nothing else.
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Offline Hayo Baan

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Re: Add Variables for certain EXIF information
« Reply #7 on: April 12, 2009, 10:35:12 AM »
just by the way: where is the distance saved in the exifs? Is it even saved? I don't find any item (Canon), that includes the distance of the object.
I'm quite sure this is a Nikon only thing and it is encoded deeply in the maker note data (e.g ., the camera/manufacturer specific data) inside the exif info.
 
I'm reading the exifs with the exiftool on a mac, my two canons (40D, 5D) do not contain distancetags. I get hyperfocaldistance, but nothing else.
Hmm, if exiftool does not show it, the data is not there (99% certainty).

Here's the lens data part of the output of exiftool when run on an image from a Nikon D3.
Lens Data Version               : 0203
Exit Pupil Position             : 93.1 mm
AF Aperture                     : 2.9
Focus Position                  : 0x04
Focus Distance                  : 6.68 m
Lens ID Number                  : 147
Lens F Stops                    : 6.00
Min Focal Length                : 24.5 mm
Max Focal Length                : 71.3 mm
Max Aperture At Min Focal       : 2.8
Max Aperture At Max Focal       : 2.8
MCU Version                     : 149
Effective Max Aperture          : 2.8


As you can see, apart from the Focus Distance, quite a number of other interesting bits are encoded as well.

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Offline platti

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Re: Add Variables for certain EXIF information
« Reply #8 on: April 13, 2009, 10:51:47 AM »
Hi,

Yeah Bayo, just go ahead with your focus distance  :P
Me, I got the circle of confusion shown in the exifs, bääh   ;D
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