Photos from a camera with an incorrect clock can appear far away from the rest of an event. Before changing dates, identify an independent reference: a known event schedule, a correctly timed picture of the same moment, or another reliable record. A plausible guess can make the collection harder to understand later.

In Photos on Mac, select a representative image and open its information with Command-I. Record the existing date and time and why you believe it is wrong. Distinguish the time of capture from the day the file was copied or imported.

Prove the correction on one image

Choose Image, Adjust Date and Time. Enter the intended value in the Adjusted field and, when necessary, choose the appropriate time zone and nearby city. Apply the change, then inspect the image’s information again.

Check where the photograph now appears relative to known images from the event. Look at the scene itself as well as the date label. An evening photograph placed before a morning arrival may reveal an incorrect date, time zone or reference assumption.

Do not select a whole mixed import merely because its files arrived together. It may contain pictures from several cameras, old scans and screenshots, each with a different reason for its date. Group only items whose correction you can justify.

Keep uncertainty visible

For a scanned historic photograph, an estimated year is different from a precise known capture time. Preserve that uncertainty in your notes or caption rather than presenting an invented day and minute as established fact.

After applying further corrections, sample the beginning, middle and end of the affected group. Recheck images near midnight, where a small time difference can also change the date.

Keep a brief record of the original values and the basis for the correction with the project. If exported dates matter to a downstream archive, inspect a sample export in that system as a separate acceptance check. Correct organisation inside Photos is one result; correct interpretation by another application must be verified there.

References: Apple: editing photo information.