How do I adjust the time that is stored with my digital photos?

I have a Canon S400 that I used to take thousands of pictures with,
however, I recently learned that the date and time setting on my
camera was off by a year and a few months.

This creates a ton of problems with most photo organizing software
(picasa in particular).  I want to find a tool/utility or approach
that will enable me to find all of the pictures taken with this camera
(I also have a Canon S200 that has the correct date/time), and adjust
the time so that it represents when the picture was actually taken.

I know the difference between actual time and camera time, so that is not an issue.

You should be able to adjust the date setting by going into a menu.

Turn on the camera and hit the button that says "menu" or takes you
into the menu options.  Now look around for something that says "date
stamp" or go through the menus to a setup and you should find the date
settings there.

Also refer to your camera manual, if my directions are too vague.

You should be able to find the camera manual online also on Canon's site.

Good Luck!

Sorry, this doesn't address my question.  I know how to change the
time on my camera (I have already done so).  I want to change the time
that is stored with the several thousand pictures I have already
taken.

Now I realize that the photos are already on your computer and you
need to change all of their dates. . .ok

The Freeware (free software) you need is
"THE Rename" it allows you to change the datem time, or file
attributes for many files at once.

You can find it here:
http://www.dirfile.com/the_rename.htm

Google Search terms:
batch edit file attributes freeware

This is really close, but doesn't quite allow me to change the time
stored with the pictures.  On reviewing the application, I learned a
few more things that should be useful.

The data elements that I need to change are EXIF tags that are
included automatically when the camera takes the picture. There are
three relevant tags:
  - Date Time
  - Date Time Digitized
  - Date Time Original

With the Canon S400, apparently all three of these tags are always set
to the same value, so I will need to change all three.

So, reiterate and clarify, the application needs to be able to review
a large set of files, and shift the three EXIF tag values by a fixed
amount (X days, Y years, Z hours).  It also needs to be able to only
conduct this shift on files that were taken by the S400 , which is
identified with another EXIF tag.

The application you identified allows me to view the EXIF tags, but
not actually make any changes to them.

Adobe Photoshop and some other image editors allow you to edit the EXIF data.

Some free programs that I found inlcude:

Opanda iEXIF Editor and Viewer 1.8
http://www.opanda.com/en/iexif/download.htm

If you are willing to pay for the program, you also have several other
programs to choose from.

I'm willing to pay for a program, but need one that will allow me to
make the date/time edits in bulk.  From what I can tell, the OPanda
program will only allow me to edit the photos 1 at a time.

jhead is a command line utility which can do time shifts on the fields
you mentioned (among other useful things).  It can also filter by
camera model.  jhead is free.  It is available at
http://www.sentex.net/~mwandel/jhead

The documentation (http://www.sentex.net/~mwandel/jhead/usage.html) is
good and supplies examples, so I'll only elaborate on a few points.

1. The relevant options are -model and -ta
2. To adjust time, you'll have to convert everything to hours and
minutes.  1 year is 8760 hours, and each month differs depending on
the number of days in it.  E.g., January has 744 hours, but February
has only 672 hours.  I'm not sure how it handles leap years--you'll
have to experiment with that.
3. Be careful: jhead overwrites the original images, so you should
make backups first until you're sure you've gotten the results you
want.
4. The S400 ebmeds the orientation of the camera at the time of
capture.  In case you are like me and don't use the Canon software to
download your pictures to your computer, you will find that the images
are not automatically oriented correctly.  jhead will correct this
with the -autorot function.
5. jhead works in batch and supports wildcards.

Hey xenophile411, 

This was the perfect utility.  I can't figure out how the heck to pay you...

Please advise.

davenaff,

No worries.  Just send a thank you to the author of jhead for me.

Cheers,
Troy

Troy, Thanks for your help.  As a way of thanking him, I ended up
buying the author a book that he had been hoping to read - Blink by
Malcom Gladwell.

Best,
Dave