Rear curtain flash technique, bowling at Fat Cats
So, a good friend of mine had his birthday and we celebrated as a big group at Fat Cats in Millcreek, UT. Bowling. And it’s not very often that I get my camera out for social purposes, at least not anymore (I tend to make a bigger deal out of things than just pointing and shooting ) The last time I did was when this same group of friends, divided in bitter rivalry, squared off against each other in their adult kickball rec league game. Naturally, being the huge event that it was, the long glass and super high ISO’s came out to play. This time around (since it was again a special occasion) I wanted to try and play around with some speedlights at the bowling alley, knowing ahead of time that it would be neon lights and all that jazz. The Nikon Creative Lighting System makes it SUPER easy to do some really fun things with their really intelligent speedlights, but you need to understand not only the principles of lighting, but also how to put them to proper use in shooting.
For this post, I wanted to explain a little as to how the following two photographs were made. The main principle behind them is a term we call “rear-curtain sync.” First, an exposure is made when the shutter in your camera opens for an amount of time, exposing either the digital sensor or the filmstrip to the light rays traveling down through the lens from your scene. The shutter opens and closes in a way that each pixel (or particle of chemical on a filmstrip) is exposed for an equal amount of time. If at any point during the time this shutter is open the flash of a speedlight fires, your subject, or whatever the speedlight is pointed at and has enough power to illuminate, will obviously be brighter than if it hadn’t fired. The key is when that speedlight fires. Is it right after the shutter opens? Right in the middle of the exposure? Or right before the shutter closes? Does it even matter? The answer is yes it matters, if you having a moving subject. Rear-curtain flash sync will trigger the speedlight to fire right before the shutter closes. The effect that it has is that with a slow shutter (these were shot with approx. 1/4 second shutters) you’re bound to have motion and/or lens blur (blur from the subject being in motion and blur from the camera itself moving during the exposure), the key is to get that blur where you want it: behind the moving subject. This is accomplished with rear-curtain flash, and by having the blur behind the subject, it gives the viewer a real sense of motion, and what direction the subject is moving. By popping the flash right at the very end, you give the digital sensor time to record all that low-light blurred mess, but then right at the last split-second you pop a good amount of light onto the subject, freezing them in place right at the end of the exposure.
The other technique I used in these photographs is called panning. Panning is when you follow a moving subject at the same rate the subject is moving (keeping the subject right in the middle of the cross-hairs as it whizzes past you) with a relatively slow shutter. By keeping the moving subject in the same position relative to your camera, the stationary background/foreground blurs as you move the lens to follow the subject. Combine that with rear-curtain flash and you get: