Rear Curtain Sync vs. Front Curtain Sync

All right Lisa, go ahead and take a walk through. Perfect, perfect. Excellent. So what we've got going here is, we've gotten up early in the morning. Light is just starting to come up.

But we're playing with our flash, but we're using both of the available curtain syncs that we can use on our flash. And it's important to know this because your camera has a front curtain sync, most cameras today also have a slow curtain sync, and they also have a front curtain sync. And there's a difference between each one. So we've got Lisa out here this morning for demonstration purposes, I've got her holding on to a headlamp as she walks by, because it helps illustrate what we're trying to do. And so, when you're looking at those illustrations of Lisa walking by using front curtain sync and rear curtain sync, you're gonna be able to see that on the rear curtain sync, the flash happens at the end of the exposure.

You'll see some publications call it "second curtain sync". Rear curtain sync is the way that I've always used this particular technique. It's also an old technique that we used to use in photojournalism, that it was called "flash and slash" because your subject would be moving in low light and as you strobed, it strobes at the end of the exposure as opposed to at the beginning of the exposure, which is front curtain sync. So you say to yourself, well what difference does it make? Well, the difference is this, if you've got a subject that's in motion, and I'm using rear curtain sync if it's a longer exposure, and they're moving through the shot.

And the exposure happens at the end of the exposure, you can get the blur, and then at the end of the exposure, pop! The flash hits them, and they're sharp. As opposed to front curtain sync as the subject moves through, the flash pops! As soon as you click the shutter, then there's motion afterwards and it becomes a blur. So there's reasons why, creatively, you want to choose one or the other.

So most of those shots that you see that are done in celebrations at night after somebody wins the World Series and it's already nighttime. And you see these pictures that are being taken down on Main Street. And it's already dark, but the exposures are still taken for ambient light. In other words, it's not just a flash on the camera that hits your subject, boom! Everything goes black behind it.

You're exposing for your ambient light. So it could be a one, two second exposure. If you've got it on rear curtain sync, at the end of that exposure, getting all that wild and good ambient light, the flash freezes your subject, gives you a sharp image. And it makes a much nicer shot. So, now I'm just gonna simply come in here and I'm going to change my camera now over to front curtain sync.

Let me readjust where I was. Right about there, okay Lis, go ahead and come through. Now the exposure's gonna happen right as she walks by. Boom. So that's front curtain sync.

The flash triggers as soon as I click the shutter, rear curtain sync it happens, the flash goes off at the end of the exposure. So, that's our demonstration. So in real life situations, look at this picture taken in the Boundary Waters Canoe Area wilderness on a dogsledding trip. Low light, finishing up the day coming back I got a dog team coming up behind me. And so I'm turning around on my sled, I've got my camera on the exact same setup that you see me using here now.

And I'm down low. Low light, ambient light. It's probably about, I think that shot was about a one second exposure. Rear curtain sync. I'm down low with my camera angle, and as the dog team from behind approaches me I'm able to get down for that one second exposure, rear curtain sync.

Fire the flash. I get a sense of movement, but I get sharpness with the dogs. And this one's even nicer, because we're both traveling at the same speed. So the variations that come with this, and your creativity, all happen based on how you decide you want to approach your subject. If it's a pan going this way, if it's a pan the same way.

You can actually follow somebody as they go, you can shoot, let 'em walk out of the shots. As you can see, it's endless possibilities. But you do have a creative tool with your flash and your camera by choosing front curtain sync or rear curtain sync. And it's an easy thing to do, most every camera has it now. And it's just another gateway to your creativity.