How the CMOS or CCD Sensor In Your Camera Sees The Light. (page 2)

The Shutter Also Impacts How Light Is Recorded

If you've ever aimed a CCD camera directly into a bright video light, you've seen what happens. Unlike with a film camera, where you'll get a halo effect, the video you record will often give you glaring vertical streaks. (However, any streaking you'll see with a CCD-based camera will pale in comparison to the severe lags and streaks that used to be commonplace with the tube-based cameras of yesteryear.)

On the other hand, most CMOS cameras use a rolling electronic shutter to capture an image sequentially in thin rows from top to bottom in the course of a single frame. The rolling shutter can generate a different type of visual distortion. Panning too quickly with a CMOS camera will often result in skew, which is a distortion of vertical lines in an image.

So What Happens on the Other End?

These days, camcorders use a variety of storage mediums. But whether it's DV or HDV tape, a hard drive or even Flash media, they're recording a digital version of the intensity of the light flowing into their lens.

On the opposite side of the lens, your computer or digital TV takes the information and reverses the above process. It increases the intensity of light in specific areas of the image it's playing back, based on the intensity of the electrical charge.

Fortunately, all of this is infinitely easier in practice than description, allowing us to focus on our overall productions, and not the tiny technological details. A computer involves a myriad of processes occurring microsecond by microsecond, but which we take for granted (at least, until it crashes). Similarly, the complex process of translating light into digital images happens at near-instantaneous speeds inside a device that, at its smallest, fits in the palm of your hand.

Perhaps what I said at the beginning was incorrect, and maybe it is magic. Or at the very least, certainly indistinguishable from it.

Edward B. Driscoll Jr. is a freelance journalist covering home theater and the media.