How to batch correct times on observations for incorrect clock?

I have roughly one hundred observations, taken at different times, from a field camera whose clock was 12 hours off (AM vs PM problem). The metadata are in the image files. I have looked and not found an answer on whether there is a simple way to adjust the time on a batch of observations to correct for this sort of problem. It would be easy to adjust it so they all have the same (incorrect) time, but I’m not sure how to quickly add 12 hours to all the different times. I would like to find an automated approach within iNat if possible because I anticipate this problem, or similar, may arise again in the large set of field camera images I am processing. I also suspect is it not uncommon for iNaturalists to notice afterwards that the time on a camera or phone was incorrect. Suggestions would be appreciated. Thank you.

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I recently had to deal with this. There’s no easy answer, unfortunately. Time zones are one of the most brutal things to deal with. Here’s what I do if I have to edit several:

  1. Make sure my account is set to whatever time zone I want the observations in. Yours doesn’t sound like the result of travel, but if so this is key.
  2. From “my observations” (your equivalent of this) click “Batch edit” and select everything I want to edit the time for.
  3. Manually change the time (and date, if needed) for each observation you selected on the batch edit page. No easy way around it.
  4. Crucially, scroll to the bottom and click “save all”.

I suppose someone might be able to some up with a clever tool using the API to edit your observations to manage a time offset issue, but nothing like that exists to my knowledge.

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Thank you @carrieseltzer! I appreciate the quick and clear response. I’d better get editing!

Good luck :-) With 100, I’d break it down by day (assuming they aren’t all the same day!) and do them in small batches so as not to lose track of how I change the date and time.

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Maybe of no help in this case, but I will mention that it is possible to correct EXIF meta data in JPG photos with various tools. I often use a command line one called “jhead” on my Linux computer. Among many things it can add/subtract a fixed about of time to each EXIF timestamp for a batch of photos. You would have to re-create your observations to get the system to read the new timestamps though.

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I’ve used ExifTool for a similar thing (adding the date & time to photos taken with my trail camera which, adding GPS location to photos taken with my camera using a track recorded on my phone).

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I’ve heard that ExifTool has a steep learning curve. @zabdiel, how much time did you need to invest before you could use it efficiently? Thank you.

Not much. I just looked up the commands for my two use cases & saved them in a text file. I can then run them from command prompt.

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