Tuesday, October 23, 2012
Solutions: Shutter Speeds & Shutter Angles
What are the best shutter speeds to use for time-lapse and for motion capture?
Time-lapse has exploded in popularity. These mesmerizing movies can show a landscape in a way that's impossible to observe in real time. Nature photographers often work to capture a sense of motion in a still frame, and time-lapse gives you a chance to show motion in a profound way as time itself is distorted.
We recommend checking out some exceptional time-lapse examples. Shawn Reeder's "Yosemite Range Of Light" (www.shawnreedervisuals.com/timelapse/) was featured in the October issue of OP. It's a brilliant time-lapse project that shows Yosemite Valley like you've never seen it. OP contributor Tony Rowell has pioneered time-lapse techniques, as well, and on his astronomytimelapse.com website, you can see a number of examples of time-lapse movies that show the night sky in motion. In what can be thought of as the definitive project of its kind, Tom Lowe's "TimeScapes" explores the American West. In Lowe's incredible film, he depicts both the speeding up and the dilating of time through breathtaking slow-motion segments. "TimeScapes" was the product of more than three years of shooting at more than 100 locations throughout the Southwest. It's one of the most inspiring looks at Southwestern landscapes you'll ever see. Go to timescapes.org for more information about the film or to buy a copy—it's available in 4K!
Taking a look at these projects will give you a sense of what's possible. These are the best of the best, but extremely high-end, sophisticated time-lapse results are possible with the gear you have now. Slow motion is more problematic because it involves shooting full HD video at shutter speeds of 60 fps, 120 fps and faster, and that can require higher-end motion cameras. For this article, we focus more on the time-lapse side.
For beginners, one of the main frustrations of time-lapse is getting the smooth look of a polished project. Think about a time-lapse that shows a busy street corner. In a lot of these types of projects, people become "blips" that wink in and out of the frame in sharp focus. That effect works for some projects, but generally, for nature time-lapse, you want a smoother look as one frame transitions to the next.
The key here is the selection of the shutter speed. Time-lapse shooters talk about "dragging the shutter"—using a slower shutter speed to create a smooth transition from one frame to the next. If you're shooting a frame every 10 seconds and each frame is 1⁄250 sec., you easily can end up with the blip effect. Instead, try slowing the shutter speed to 1⁄40 to 1⁄50 sec. This seems counterintuitive to still shooters who have always valued sharpness, but when you're creating a motion project, a little blur is often preferred.
Filmmakers refer to the concept of "shutter angle," which comes from film-based movie cameras with rotary shutters. Many cinematographers use a shutter angle of 180º, which is roughly equal to 1⁄50 sec. at 24 fps. At that shutter speed, the amount of blur is just right. You may say you're not shooting at 24 fps, but in effect, you are, as that's the rate at which you're going to play the time-lapse.
This rule of thumb should be a starting point for your experimentation. Variables such as the sort of time-lapse you're creating—whether it's starscapes, fast-moving clouds or just the light moving over a landscape—will dictate the precise shutter speed to use.
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