Zoom factor

     Most digital cameras are now equipped with zoom functions allowing the user to get closer pictures of scene without having to physically move forward or backward. A zoom lens is any lens that has an adjustable focal length. Zoom doesn't always mean a close-up. Digital cameras have three types of zoom functions: an optical zoom, a digital zoom, or both.

     An optical zoom actually changes the focal length of your lens. As a result, the image is magnified by the lens (sometimes called the optics, hence "optical" zoom). With greater magnification, the light is spread across the entire CCD sensor and all of the pixels can be used. You can think of an optical zoom as a true zoom that will improve the quality of your pictures.

     A digital zoom is a computer trick that magnifies a portion of the information that hits the sensor. Let's say you are shooting a picture with a 2X digital zoom. The camera will use half of the pixels at the center of the CCD sensor and ignore all the other pixels. Then it will use interpolation techniques to add detail to the photo. Although it may look like you are shooting a picture with twice the magnification, you can get the same results by shooting the photo without a zoom and blowing up the picture using your computer software. Hence, a digital zoom is not recommended for professional use due to the ‘artifacts’ introduced into the image by the enlargement.