Date Time

[Wil]

I have tried to get info about this subject on the Lightroom forum, but got no help.

There are four Date Time entries in the Lightroom 4.1 metadata:

Metadata Date
  I don't know what this means, but it seems to be given in the time of the current time zone.

Date Time Original
  This seems to be the date time when the image was captured and given in UTC time.

Date Time Digitized
  I don't know how this differs from "DateTime Original",  but it seems to be in UTC time.  It is sometimes the same, but not always as "Date Time Original."

Date Time
  I don't know what this means, but it seems to be given in the current time zone.

It seems be obvious that the UTC times come directly from the camera, but where do the times for the current time zones come from?  I can't find any way to set the current time zone in Lightroom.  I suspect it comes from the computer system clock.

I hope someone knows the answer to these questions.

Wil

[dneuman]

EXIF will include the Date Time "original", "digitized" and plain "date time" as part of its metadata.
IPTC will include "Date Created" as part of its metadata.

I believe what you are looking at is the EXIF and IPTC metadata together. Ordinarily Date time original, digitized and simple date time should all be the same if you are importing digital photographs. Your "metadata date" may be what you have in your metadata template (I cannot find a metadata date rubric).

The distinction between "original" and "digitized" allows you to utilize and date scanned photos. The original might be 2/2/1954 but the actual date of the scan could by 11/15/2011.

The time zone would be established in your camera, not in LR. Where do you read UTC times?

[Wil]

Canon 5DIII, Win7

You are right about the EXIF and IPTC stuff.  I have them both checked.  I have now checked EXIF only for what follows.

I have set the time zone in the camera to be London without correcting for daylight saving time to be in sync with UCT.  I live in, and my computer is set for the eastern time zone with correction for DST. 

Here are the EXIF times of a shot I just made.  The image was imported as dng, and no modifications have been made.

Date Time Original      8/24/2012 7:04:07 PM
Date Time Digitized   8/24/2012 7:04:07 PM
Date Time      8/24/2012 3:05:40 PM

Note that both "Date Time Original" and "DateTime Digitized" are correct for UTC, and "Date Time" is close for EDT.

The strange thing is the "Date Time" entry.  After correcting for the time zone difference, it is 93 seconds different from the other two.  A check of the camera clock and the computer clock indicates a difference of only 4 seconds after allowing for the time zone difference.

It's all very strange!  It surely seems that all of the EXIF data should come from the camera, but this example shows that something strange is going on.

Wil

[dneuman]

You correct; that 93 seconds of difference makes no sense. My guess is that it is a bug in LR and the way it is "reading" your computer time. Let me know if you find anything out.