Digital Photography: The Missing Manual

Burst Mode for Rapid-Fire Shooting

When you press the shutter button on a typical digital camera, the image begins a long tour through the camera’s guts. First, the lens projects the image onto an electronic sensor—a CCD (Charge-Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor). Second, the sensor dumps the image temporarily into the camera’s built-in memory (a memory buffer). Finally, the camera’s circuitry feeds the image from its memory buffer onto the memory card.

You may be wondering about that second step. Why don’t digital cameras record the image directly to the memory card?

The answer is simple: Unless your camera has state-of-the-art electronics, it would take forever. You’d only be able to take a new picture every few seconds or so. By stashing shots into a memory buffer as a temporary holding tank (a very fast process) before recording the image on the memory card (a much slower process), the camera frees up its attention so that you can take another photo quickly. The camera catches up later, when you’ve released the shutter button. (This is one reason why digital cameras aren’t as responsive as film cameras, which transfer images directly from lens to film.)

The size of your camera’s memory buffer affects your life in a couple of different ways. First, it permits certain cameras to have a burst mode, which lets you fire off several shots per second. That’s a great feature when you’re trying to capture an extremely fleeting scene, such as a great soccer ...