Jason Snell, Six Colors:

I went to a wedding in London over the summer, and as you might expect at an event full of techy people, I ended up with hundreds of photos of the event from numerous sources—at least six. I imported them all into my Photos library and then discovered that they were all mixed up—the bride walking down the aisle, immediately followed by dancing at the reception, followed by the exchanging of vows.

This happens to me every time I get photos from other folks and try to mix them with my own photos of the same event. This is especially true when I travel with a group, and we each have our own view of the same series of locations.

The issue, for the most part, is the time stamps and device clocks:

Most cameras embed time data on every file they take, which is great, but whenever I try to mix photos from multiple sources in one place, I end up discovering all the ways that the clocks don’t match. For some of them, the clock is right but the time zone is wrong. For others (especially non-cellular devices that rely on a human to set their clock correctly) there are a few minutes of drift. For still others, there’s a time but not a time zone embedded.

Though this is less and less an issue as more and more photos are taken with clocks set by servers, there are still time zone issues, as well as photos taken using regular cameras.

Take the time to make your way through Jason’s post. If nothing else, I appreciate the walkthrough of smart albums and what they can do for you. Great stuff.