Aperture ha stwo time adjustments:
One adjustment is for correcting the Time Zone: If your camera was set to a different timezone then the actual time, you use "Metadata > Batch Change"
- You set "Camera's Time Zone" to the Time Zone your Camera has been set to, when you took the pictures.
- You set "Actual Time Zone" to the Time Zone you want the images to show.
For example: If your camera is stuck on European time, but you took the pictures in London, set the "Camera's Time Zome" to "MET" (Paris) and the Actual Time to GMT (London).
The second adjustment is for correcting inaccuracies. If your camera's time is inaccurate - e.g. off by several minutes, you can correct that by "Metadata > Adjust Date and Time". The panel will show the current time for one of the images and you can adjust this to the correct time. All other selected images will be adjusted by the same amount.