Photographing Water Using the Multiplication Factor Technique

More is easier than it used to be. It's also a lot more creative.

By more we mean multiple exposures—an age-old technique made new by digital photography. Simply, it means taking two or more exposures on the same frame. That used to mean a frame of film; today it means multiple capture on the camera's sensor.

It's a technique that nature photographer Rod Planck has been working with lately, especially in scenes that portray moving water.

"It's a way of getting a different look to the water," Rod says. "The idea is to create a sharp landscape and have the multiple exposures layer the movement of the water so that I get a contrast of textures."

For photos like these, Rod follows the golden rules of multiple exposures: camera on a tripod, mirror locked up, shutter tripped by electronic release. "Nothing can move except the water," he says, and he's not kidding.

When the subject's not water, there's still a lot that can be done. "Many times I'll hand-hold the camera and deliberately move it to dapple one exposure onto another to get a painterly look to the image." While this might sound mostly experimental, there is a degree of control.  "I compose the photo the same way I would if I were using a tripod, but I'm hand holding with the composition mapped out in my mind." Camera movements are slight as he makes the exposures. "If you move the camera too much you lose all definition in what you're photographing. So there's a magic amount of movement—enough that it's obvious that you're creating a technique, but not so much that there's no idea of what you're actually photographing." There's also such a thing as too little movement: "If you hand hold too well—that is, don't move the camera enough-you create a photograph that looks like you made a mistake." And thus the idea of "a magic amount of movement."

By now you're probably wondering about Rod's definition of multiple. Just how many exposures does he make for one image? Well, he has no hard and fast rules, but the number ten shows up a lot in his calculations. In fact, each of the photos you see here is comprised of ten separate exposures.

Nikon technology offers ease and control when it comes to making multiples. Access the camera's menu and simply choose the number of exposures you'd like.

Then make one more choice: set the camera for auto gain on or auto gain off. Think of auto gain as an automatic exposure compensation. It takes into account the number of multiples you've chosen to make and reduces the exposure of each one so the buildup results in an accurate exposure. Turn auto gain off and you're in control; each image in the multiple will adhere to the exposure choices you've made.

Rod chooses auto gain most of the time, but will go manual in specific cases. For example, the first image accompanying this story, the waterfall and rainbow. "If I'm in a brightly-lit situation and have a relatively fast shutter speed, say about 1/250 or 1/400 second, I can find that the water won't show either a silky look or a stop-action effect—I'll be in between. So I turn off the auto gain, go to manual exposure from my usual aperture priority setting and then add a zero to whatever shutter speed I had if I'm planning to shoot ten exposures. So a 1/250 second becomes 1/2500 second, and now I've got a stop action effect while the layers of exposure build up a silky look."

One of Rod's multiple methods combines new and not-so-new technology. Take a look at the last photo, a multiple image of a penguin colony. It's a variation of the old zoom-the-lens-as-you-make-a-slow-shutter-speed-exposure. Only here the lens was zoomed between each exposure of the ten-image multiple.

Rod has two final tips to offer:

"Making ten exposures takes a while, especially if you're on a tripod, locking up the mirror and using an electronic release," Rod says. "You want to make sure your exposure is correct, so it's a good idea to make a test shot and check the histogram. The histogram doesn't change on multiples, so I always shoot a test to be sure the histogram is right where I want it as far as the exposure is concerned.

"Often I'll set a particular focus point from the camera's array—one of the 51 points from the D3, for instance—and use it as a reference point for my subject. Say I've got a field of wildflowers. I'll look at one focus point and see that it's always positioned on one particular flower for all ten of the exposures. I'll make sure I don't move the camera so much that the sensor totally leaves that flower. I don't want to be creating color with no edges to it—I need some edge detail to create a painterly look."

So there you have it. Go forth and multiply.

Be sure to check out our related story on image overlay here.

And visit Rod Planck's site at www.rodplanck.com to see more of his photography and learn about his workshops.