How to correctly set base timezone with `AllDates` tag alias?

[mesqueeb]

I have set the same datetime for scanned photos on 4 tags: `-AllDates` and `-MDItemFSCreationDate`.

When I check the result with:

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exiftool filename -AllDates -MDItemFSCreationDate -n

I get:

Date/Time Original           : 1985:10:01 18:13:01
Create Date                     : 1985:10:01 18:13:01
Modify Date                     : 1985:10:01 18:13:01
MD Item FS Creation Date : 1985:10:01 18:13:01+09:00

I want to preferably set the hour to 12:00 (noon) on GMT +01:00 (because they were taken around noon in a GMT +01:00 timezone)
I am currently in a GMT+09:00 timezone.

My Questions:

1. Is the datetime on these 4 tags currently the same? Or is the bottom one different?
2. How can I make sure that if I open the photo in a GMT+01:00 timezone it will show 12:00 (noon) for the hour? (nevermind the minutes)

(PS, I have not set GPS datetime, since I personally was confused by the documentation and wanted to avoid errors and over-complication. I'm open to try if this is my only option however.)

Best regards!

[Hayo Baan]

IF datatime original was gotten from the camera, it would be a local time without timezone info (and would normally be the time used by software to show the data taken). The other dates are always (local) times with timezones applied. And if your computer is set to +09:00, they all would be the same.

Setting the datetime taken to 12:00 would be accomplished by e.g.:

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exiftool -datetimeoriginal='1985:10:01 12:00:00' filename
The file modification/creation dates are best left alone since they are unreliable anyway (e.g. they would change each time an image is edited).

To be sure the date is set correctly using the above command, can you show the output of

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exiftool -G0:1 filename -AllDates -MDItemFSCreationDate

[mesqueeb]

@HayoBaan
Thank you for your post.

I have edited my post to state that the photos were scanned, so there is no metadata of any kind and also no GPS data.

I have tried your command `exiftool -G0:1 filename -AllDates -MDItemFSCreationDate` and I got the same result:
- Only `MDItemFSCreationDate` says `18:00:00+09:00` while the others just say `18:00:00`.

I'm unfortunately still confused about my question, even with your explanation:

Are these datetimes the same even if just one says +09:00? Or is only `MDItemFSCreationDate` read as 12:00 on GMT+1 because it has the +09:00 and the rest read as 18:00 even on GMT+1?

Any help much appreciated!

[Hayo Baan]

Yes, they are all the same; they are all local times and since you are in +09:00 they are all the same.


Note, however, that depending on the group of the tags, there might be some exceptions, so to fully answer your question I really need to have the output of

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exiftool -G0:1 -AllDates -MDItemFSCreationDate filename