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Christmas Prize Draw 2017

Understanding EXIF


saltireblue Plus
7 7.4k 33 United Kingdom
11 Oct 2017 6:33PM
Here is the embedded EXIF from an image.
I cannot understand the relationship between these 2 pieces of information.

The second line shows the correct date and time the image was taken. 10:16 am on the 27th Aug.
The upper line shows a time 8 hours earlier when the photographer was safely tucked up in his bed!

In another example, the time difference was 4 hours and in yet another 5 hours.

Can anyone explain what the first line means as the second line shows the time the image was actually taken.

128530_1507743199.jpg

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11 Oct 2017 6:48PM
Time zone?
saltireblue Plus
7 7.4k 33 United Kingdom
11 Oct 2017 6:53PM

Quote:Time zone?

HardlySmile...otherwise the time difference would be the same on the all examples...
11 Oct 2017 7:00PM
I just had a look at the memory card in my 6D - all the dates and times on an image I looked at are the same. However, I have noticed that when I copy them to the drive on my computer the dates go a little odd. Sometimes the "modified" date is before the creation date, when the creation date is the actual date and time I took the photograph.

Probably one of the oddities of EXIF and computer filesystems. Looking at older photos on my drive from a camera I no longer have, a similar thing seems to happen.
banehawi Plus
13 1.7k 3783 Canada
11 Oct 2017 7:37PM
What did you use to read this data?
saltireblue Plus
7 7.4k 33 United Kingdom
11 Oct 2017 8:11PM

Quote:What did you use to read this data?

EXIF viewer in F’fox
Philh04 Plus
12 1.3k United Kingdom
11 Oct 2017 9:03PM
The line with the tag {0x9003} should be the correct one for when the image data was recorded so I would guess that the time is probably wrongly set in the camera.

I'm not sure where the data for the line tagged {0x9004} is being obtained from, in fact it is not an often used tag. The first line (Exif.Image.DateTimeOriginal) is the most commonly used.

Not sure if that is any help Tongue
EddieAC Plus
13 1.8k 2 United Kingdom
11 Oct 2017 9:10PM
I can't see why it would but at a wild guess is the camera recording the first time as that in Japan where the second time is correct for you in Norway?
11 Oct 2017 9:24PM
There are multiple versions of EXIF and not all cameras use them correctly. I recently looked into writing some program code to iterate through the 25,000 or so images on my drives and extract EXIF data if it existed, and those images are from about eight different cameras as well as two models of scanner - and it seems the implementation of EXIF by even quite professional organisations is, to put it charitably, inconsistent.

So very possibly browsers, plug-ins, file managers and cameras all have different expectation as to what should be in a given field, and when they come across unexpected data they perhaps forgivably get it wrong. Oddly enough, though, it is inconsistent even within a single camera - picking images at random all shot on one camera with the same SD card and stored on the same drive, some have all dates the same, some have modify dates later than creation dates, some have apparently been modified before they were created. Unless Canon has discovered the secrets of time travel, it's probably best to assume there are big flaws in EXIF.

Note to Canon - if you HAVE discovered time travel, please go back three or four years and decide to keep making the 1V.
Fma7 2 791 United Kingdom
11 Oct 2017 10:56PM

Quote:Note to Canon - if you HAVE discovered time travel, please go back three or four years and decide to keep making the 1V.


If it's not too much trouble a quick scoot to the future for some lottery numbers would be appreciated too. Smile
11 Oct 2017 11:02PM
Nah, a shiny new 1V would be favourite.

Clearly my priorities are misplaced.
saltireblue Plus
7 7.4k 33 United Kingdom
12 Oct 2017 5:59AM
Thanks all for your thoughts thus far.
Further digging makes me suspect that this 'quirk' may just be related to one particular camera. A particular camera, not a brand or model.
Further research is on-going.
Next step to find out if it is camera or card related...

@EddieAC - the camera in questionis in the UK, and the time differance varies from shot to shot.
Dave_Canon 11 1.3k United Kingdom
12 Oct 2017 9:43AM
I have just checked a random sample of my images in LR from 3 different Canon DSLR's and for each frame, the Original Date/Time and Digitisation Date/Time was identical.

Dave
saltireblue Plus
7 7.4k 33 United Kingdom
12 Oct 2017 9:53AM
Thanks Dave.
The owner of the camera seems to think it may be something to do with his slightly older version of Elements which has a problem with this newer camera. Another older camera shows the correct times...
sherlob Plus
11 2.9k 129 United Kingdom
12 Oct 2017 2:19PM
Malc,

As I understand it, this is explained by Willy Wonkers theory of quantum physics: the subject of a digital image must first be digitized before the image can be transported electronically. The theory is rather complex, but basically the subject of an image 'knows' that it is to be photographed before the image is taken (multi-dimensional theory is in play here) and begins the process of self-digitalization to enable the digital image to be recorded. The camera can extrapolate the digitization time from the time the image is actually taken based on a mathematical formula (different manufacturers dispute the best formula to use).

You may be interested to learn that Willy Wonker's experiments for transmitting chocolate via TV were fundamental in the development of his quantum theory.

I trust this explanation clears up any confusion you have and will prevent you from over scrutinising your exif data in the future.

Adam Wink

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