Manipulating file dates

[Lennart Sorensen]

On Wed, Mar 31, 2010 at 04:47:07AM -0400, Mike Oliver wrote:
> With that or with exiftool, you'll have to do some scripting, which
> is fine if you like that sort of thing, but it isn't really necessary.
> The "jhead" command will allow you to specify a delta from the existing
> EXIF timestamp, and apply it to *.jpg in a directory.  Use
> "jhead -ta hh:mm:ss" (or a minus sign in the obvious place
> for a negative delta).
>
> One good trick, if you're using a GPS and you want to correlate
> the photos based on the timestamp, is to take a shot of the GPSs
> time display, so that you know the exact delta.
>
> Unfortunately it works only on JPEGs (and not, for example,
> on DNGs, which also have EXIF headers).
>
> One final remark -- I've come to the conclusion that it's simply
> better *not* to reset your camera's clock to the new time zone when
> travelling (or your laptop's, either), unless it's quite a long trip.
> It's easier to remember to convert those times in your head than it
> is to figure out which timestamps apply to which time zone.  Very much
> too bad that timestamps don't include time-zone info, to allow automatic
> conversion.

Some cameras have GPS stamps on pictures.  That would let you figure
out what timezone it was in.

-- 
Len Sorensen
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