Before EXIF data landed on the scene through the rise of digital photography, film cameras could superimpose the current date directly onto your photos, allowing you to see when you shot each one as you flipped through an album. If you've ever wondered how that date was included, here's an interesting 14-minute teardown by Applied Science that reveals the secret.
Shooting two or more cameras generally means you need to ensure the cameras are all synchronized to the same clock time. Unfortunately, my Canon 5D Mark III drifts horrendously when it comes to keeping good time -- perhaps even 20 seconds in a week. I found myself continuously having to set each of my cameras before each wedding shoot to ensure images are timestamped in the right order.
After giving it a think, I came up with this handy way to sync my two DSLR cameras using Lightroom and a "Timestamp" trick.
If you've ever needed to deal with photos shot with multiple cameras at the same event, you've probably found how important the clocks on the cameras are for keeping the resulting photos neat and orderly. If timestamps are off, then figuring out when photos were captured in relation to each other can be a pain.
One way you can make sure the clocks on your cameras are perfectly synchronized is by automatically synchronizing them to your computer.
Here's a friendly public service announcement: remember to time on your camera before and after Daylight Savings Time (which just ended yesterday in the United States) -- unlike cell phones, digital cameras generally don't adjust their own time. If you accidentally forgot and now have a bunch of photos with timestamps that are off by an hour, there are some programs out there that can help you set things right.