DateTimeOriginal is the EXIF tag that records when a picture was taken, read from the camera clock at the moment of capture. Windows Explorer calls it "Date taken" and Lightroom uses it as capture time. It is tag 0x9003 and lives in the Exif sub-IFD, not in IFD0.
Format, and the missing time zone
The value is a fixed 20-byte ASCII string: YYYY:MM:DD HH:MM:SS plus a terminating null. Colons in the date part, a 24-hour clock, nothing below one second. Fractions go in a separate tag, SubSecTimeOriginal (0x9291), as a string of digits, so 315 means 0.315 s. ExifTool merges the two:
[ExifIFD] DateTimeOriginal : 2026:05:14 18:42:07
[ExifIFD] SubSecTimeOriginal : 315
[Composite] SubSecDateTimeOriginal : 2026:05:14 18:42:07.315There is no time zone. The value is whatever the camera believed local time was, so a body left on home time during a trip, or one that never switched to daylight saving, is off by whole hours. Since EXIF 2.31 the zone can be stored next to it in OffsetTimeOriginal (see OffsetTime); once present, the composite above gains a +02:00 suffix.
Cameras and phones write the tag once, at capture, and editors are expected to carry it over to exports unchanged. Messaging apps that strip EXIF take it with them. Many photo managers then fall back to CreateDate or the file system date, which is how a 2019 photo ends up sorted under the day it was downloaded.
Changing it
For a single JPEG or TIFF, the EXIF editor has it as Date Taken in the EXIF Date & Time panel, next to its time zone field. Type the value in EXIF format, 2026:05:14 18:42:07. The editor writes the EXIF copy only; XMP and IPTC dates keep their old values. For batches and shifts, ExifTool:
exiftool -DateTimeOriginal="2026:05:14 18:42:07" photo.jpg
exiftool "-AllDates+=1" photo.jpg
exiftool "-DateTimeOriginal<Filename" IMG_20260514_184207.jpgThe second line moves DateTimeOriginal, CreateDate and ModifyDate forward one hour, the usual repair after a missed daylight saving change. Use -= to go back, or the full form for bigger shifts: "-AllDates-=0:0:1 2:30:0" subtracts one day and two and a half hours. The third line pulls the digits out of a phone-style file name. ExifTool keeps a _original backup unless you add -overwrite_original.
The tag is identical in a JPEG and a HEIC file, since both carry the same TIFF-structured EXIF block. For doing it from the operating system or a phone app, see the guide to changing the date taken.