Both optical and digital zoom magnify subjects.
Almost all consumer point-and-shoot cameras have both optical and digital zoom. While both of these processes will magnify your subject, they work in completely different ways. Knowing the technical details, advantages and disadvantages of both will improve your ability to shoot quality photos.
How They Work
Optical zoom is what you probably think of when you think of zoom. When you adjust the optical zoom, you adjust the physical pieces of glass in the lens. By affecting the arrangement of the optics, you increase the image as it hits the image sensor. Digital zoom, on the other hand, simply blows up the image on a limited area of the image sensor. Technically, this is not "zooming" in; it is merely cropping the image that the sensor sees to enlarge it on the LCD.
The Result
With a quality optical zoom, your camera sees a larger image that is as high quality as a zoomed-out photo. However, a digital zoom typically degrades an image as it magnifies it. Because the camera is only increasing one area of the image sensor, you are more able to see the pixelation and noise with each successive zoom level.
Which Is Better?
By far, optical zoom is the superior choice for achieving high-quality images while zooming. It results in a more pure image, while digital zoom often causes graininess. Digital zoom ability is often listed in the product description as a marketing tactic, especially if the level is extremely high, such as 300x magnification.
When Should I Use Either?
If possible, always use optical zoom and never digital zoom. If your subject is too tiny when you're at your maximum optical zoom, you can still take the photo and then enlarge the subject later when post-processing. If you find yourself in a difficult situation, you can use the digital zoom, but you should be aware you are losing image quality with each successive magnification.
Tags: digital zoom, optical zoom, image sensor, area image, area image sensor