EXIF time stamps

Terry Pinnell wrote:

VanguardLH wrote:

Terry Pinnell wrote:

VanguardLH wrote:

Terry Pinnell wrote:

I'm struggling to determine the times at which my
holiday photos in Italy were taken with my iPhone.

This illustration of IrfanView windows hopefully states my questions
clearly:

https://www.dropbox.com/s/hcrzd9nxf9...ps-01.jpg?dl=0

Looks like an hour difference between meta-data datestamp and file
datestamp. Is one device set to use DST and the other not?

Meta-data is static. The device writes the meta-data at the time the
photo is taken and the meta-data stays that way no matter how time
thereafter changes on your phone. Copying a file would change its
timestamp in the file system but not alter any meta-data which is
contained within the file. Since the timestamps in the meta-data and
Irfanview are the same to the second, I'm guessing you removed a memory
card and slid it into a reader on your computer and that is where you
are using Irfanview to look at the file. That way you would not have
copied the file to change the timestamp. Could be your phone and
computer are set to use different DST offsets.

The phone likely locks in the current time regardless of where it is:
Italy, home, wherever. That won't change the meta-data in the file
recorded at the time of taking the photo. Don't know how your computer
is setup for DST or if it is even configured for the correct timezone.

Thanks both.

Time is set automatically on iPhone/iPad/Win 10 PC. (Settings General
Date and Time Set Automatically.)

The iOS devices were set correctly during my holiday in Italy as time
zone is automatically changed.

A photo take with the iPhone just now here in UK shows all four of those
dates are identical in a similar IrfanView screenshot. Note that it
automatically gets named 2017-06-09 10.03.38.jpg. I rename that (with a
macro, or in volume with Bulk Rename Utility) to the form
yyyymmdd-hhmmss. In this case 20170609-100338.jpg.

I'm still hazy as to why all my iPhone photos taken in Italy have that
IrfanView Properties date showing UK BST, while the EXIF window
correctly shows CEST. More coffee and I might get it...

Terry, East Grinstead, UK

But you are NOT running Irfanview on your phone. You are running it on
your computer. How did you get the photos from your phone to your
computer?

Uploaded to my PC via Dropbox.

Since the timestamp of the file is identical to the
timestamps in the meta-data but different by 1 hour, I suspect your
computer is looking at the timestamp on the file and biasing its
presentation in your file system per your regional time settings in your
computer.

Certainly sounds like you may be onto something, although I won't claim
to have got my head around it yet. And I'd have expected to see this
potential cause of confusion being discussed more widely, given the
number of iPhone/iPad users.

What's your view about the relevance of the article referenced by
Shadow?

When you were in Italy taking photos on your phone, did your phone
adjust for DST? Now that you're back home, is your phone showing the
correct local time or is it off by an hour? Is your home locale using
DST or not? What was the timezone for your phone at that you were in
Italy? What is the timezone for your home computer?


As I said in my previous post: "Time is set automatically on
iPhone/iPad/Win 10 PC," and "The iOS devices were set correctly during
my holiday in Italy as time zone is automatically changed."

So:
- Yes, it showed CEST (Central European Summer Time, GMT/UTC+0200)
- Yes, it shows correct time
- Yes, 'correct' obviously means BST
- (Again) CEST
- BST


Don't know how you are getting the photo from your phone to your
computer. If you copied the file, it would get a new timestamp since it
is a new file. Did you move a memory card from phone to computer? If
so, if you put the card back in your phone, what does it show for the
file's timestamp?

I answered that above.

Do you have a smartphone? It sounds not. Upload of photos from
smartphones (iOS, android, Windows) is a rather commonplace operation
these days. It's almost entirely done online, via wifi or 3G/4G.

Terry, East Grinstead, UK

In case it offers further clues, for the photo example in my earlier
illustration, here is all the data on Date/Time reported by Win 10. Even
more elements than I thought, although most are empty.

https://www.dropbox.com/s/1nr6sfeu0q...ments.jpg?dl=0

BTW, with apologies for digressing, I just viewed it in IrfanView and
closed it again, and was surprised that did not change 'Date accessed'.
So then (without editing) I resaved it - but no change in 'Date last
saved'. Then I edited it and resaved, but STILL no change to 'Date last
saved'! FWIW, this was working on a backup copy on a 2 TB USB HD,
although I don't see how that's a factor?

Terry, East Grinstead, UK