For both examples, we will imagine that we’re taking pictures with a 5MP camera that is set to capture images at the highest quality level.

Optical zoom uses the camera’s lens (optics) to magnify the view. When using only optical zoom, the camera will capture an image file containing 5MP of information. Because only the camera’s lens is used to capture the full amount of megapixels, your image will be sharper and smoother than with digital zoom.

Digital zoom, which you can usually turn on or off in the camera’s setup menu, engages when you’ve zoomed in as far as you can with the optical zoom. When looking at the camera’s LCD or through the viewfinder, it appears that the camera is zooming in even more, but in reality, the camera has simply enlarged part of the image and cropped the rest. By cropping the image, the camera has discarded some of the image’s pixels, leaving you with an image that contains far fewer pixels than one shot with an optical zoom. For example, using our previous 5MP camera, we take a picture that engages digital zoom. The camera crops out 2MP of image data so the image file now contains only 3MP of image data. Because we’re using a 5MP camera, however, the camera must produce an image with 5MP of data. In order to do this, the camera interpolates (invents) the missing pixels and adds them to the image file. The resulting image is almost always softer than the original, and individual pixels may be visible when the picture is enlarged.

So, when you’re shopping for a digital camera, ignore the digital zoom specifications. And, for the best image quality and ability to make larger prints, use only the optical zoom when shooting.

by Theano Nikitas