Some of the more inexpensive digital cameras have a fixed lens. This means if you want to enlarge the image in the viewfinder, you have to get closer to the object. Others have a control which allows the user to zoom in and out from the scene.

When you capture an image, light travels into the lens. Since light travels in a straight line through a given medium (air in this case), only the light which is lined up with the lens will enter. The lens system will view only a given area of the scene. When the user adjusts the zoom controller, the area detected by the camera changes.

Sarah and Nate are using yarn to illustrate the viewing angles for the zoom settings on a given camera. "Zooming out" or the wide angle setting captures a larger field of view. "Zooming in" or the telephoto setting captures a smaller field of view, as illustrated in the camera's LCD screen in the image on the right.

The two sets of images below were taken by two different digital cameras. The top set was taken by the Sony FD91, which has a 14x optical zoom. The second set of images were taken by an Olympus D-460.

Full Wide Angle

Full Telephoto

The two images shown above illustrate the maximum range of the Sony FD91. The stick in the image is a meterstick. The image on top (full wide angle) represents a length of about 112 centimeters. The image on the bottom (full telephoto) represents a length of 9.1 centimeters. What was the zoom factor? Is it close to 14x?

Wide Angle View

Full Optical Zoom

Full Optical and Digital Zoom

The image set above shows the maximum ranges of the Olympus D-460 digital camera. It has an optical zoom, and a digital zoom. The top image represents totally wide angle viewing (width of the picture represents 113 cm). The middle image represents full optical zoom (represents 39.4 cm). The bottom image represents a full optical and full digital zoom (represents 19.8 cm).

What is the optical zoom for the Olympus D-460 camera? What is the digital zoom?

Zooming is a convenient feature to have on a digital camera, but it is not required for most applications in teaching. The more the optics can zoom, the more expensive the camera.

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