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Graphic by: Jenny Conner |
Your thrifty new digital camera will have both an optical and a digital zoom. So what's the difference? What should you look for? Is zoom really important at all?
Before we can examine optical zoom, we must know what it is first. But before we can understand what optical zoom is, we have to understand focal length. The focal length of a lens is defined as the distance in millimeters from the optical center of the lens to the focal point, which is located on the sensor or film if the image is "in focus." Here's an illustration:
If you divide the maximum focal length by the minimum focal length of a zoom lens, you get the optical zoom or magnification factor. This factor describes the ability of a lens to multiply the size of a subject between its minimum and maximum focal lengths. All cameras, digital or not, have an optical zoom. Likewise, optical zoom should not be confused with digital zoom.
Digital zoom is not very effective for several reasons. For example, a 1.6X digital zoom will only use the information of a 1,600 x 1,200 resolution crop regardless of how big your camera's megapixel resolution is. It will capture the same field of view as a comparable optical zoom lens, but at a fraction of the resolution. This means your pictures won't be as good a quality.
Many digital camera users simply turn their digital zoom off to avoid this. It is for this reason that you should not be too easily impressed with any camera's advertisements about digital zoom. It is not a very effective feature. The bigger the optical zoom, the better.
Of course, not all digital zooms are created equal. Like always, do research and compare models.
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Your Thrifty New Digital Camera, Part III: Zoom Zoom