All digital cameras don't 'think' alike

Camera Angles

By Rick Sammon ~ The Associated Press

Not all digital cameras are created equal. For example, I'm sure you know that different models offer different-sized megapixel image sensors (megapixel meaning millions of pixels or picture elements), such as 2, 3, 4, 5 and now even 6 megapixels. Usually, the more pixels, the better the image quality -- although some 4-megapixel cameras with a CCD image sensor produce a better image than some 6-megapixel cameras with a CMOS sensor.

But the number of pixels (and the sensor) is not your only consideration when choosing a digital camera. Of course, a lens' zoom range is important -- the greater the range, the more versatile the camera. But there are two often overlooked features that you should consider when choosing a digital camera. Both have to do with image-processing speed or "thinking time."

One is what's technically called "shutter lag." That's the time between when you press the shutter-release button (although consumer digital cameras don't always have shutters in the traditional technical sense) and the time when the picture is taken. On low-end cameras, shutter lag can make the difference between getting a fast-moving subject in the frame -- or out! On high-end consumer digital cameras, shutter lag is reduced. And on professional digital cameras, shutter lag is, for all practical purposes, eliminated -- which is one reason why these cameras can cost up to $5,000.

So, when looking at a digital camera, ask the salesperson about the shutter lag (aka shutter delay). If you can, take a picture with the camera. In most cases, you will be able to tell immediately whether the camera has a noticeable shutter lag -- because most cameras have an audible click to indicate when the picture is taken.

The other thing to consider when looking at a digital camera is the time it takes for the camera to "write" the picture to the memory card. Initially the photo is written to a buffer memory, and when that's full is transferred to the memory card. Low-end consumer cameras don't have as large a buffer or write as fast as high-end consumer ones -- which means you could miss a shot while one picture is being "written" to a card. In addition, low battery levels can cause an image to be written to a card slower than if the battery is at full charge.

Of course, these are moot points if you shoot landscapes, where nothing much moves.

So, if you are thinking about a digital camera, consider how fast the camera can "think."

Rick Sammon is the author of 21 photography, nature and conservation books.