Zooming during image capture
Zoom lenses for cameras come in two basic types: optical zoom and digital zoom. With an optical zoom lens, the focal length of the lens is variable within a range. Digital zoom lenses do not actually zoom; instead a portion of the image area is enlarged and cropped to simulate a zoom. Some point-and-shoot cameras have both optical and digital zoom.
Optical Zoom
Optical zoom lenses actually move in and out to change the focal length of the lens, while remaining in focus. The ranges are expressed in focal length. A focal length of 50mm to 55mm is considered a "normal" perspective for a 35mm film camera or DSLR with a similar-sized sensor. A zoom lens with a focal length from 55mm to 200mm is a telephoto zoom lens. A zoom lens from 24mm to 55mm is considered a wide-angle zoom lens.
Digital Zoom
Digital zoom lenses do not have the quality of an optical zoom lens. They work by taking a sample of your subject, and as you zoom they magnify the sample. The higher the zoom, the worse the quality. Digital zooms can result in pixilation. Digital zoom lenses are described in magnification factors from a normal perspective of 55mm. A 2X zoom will yield a result similar to a 110mm optical zoom.
Image Quality
Although optical zoom lenses are considered to be of higher quality than digital zoom lenses, all lenses exhibit different characteristics. Lenses with glass elements perform better than lenses with plastic elements. If you need a long lens, it is better to buy a telephoto converter than to use a digital zoom lens. There is a significant quality difference between the two types of zoom lenses.
Point-and-Shoot Cameras
Most point-and-shoot cameras use a combination of optical and digital zoom lens. You will notice that as you zoom, the lens extends a little to alter the focal length. If you zoom further, the image is zoomed using a digital zoom. Normally point-and-shoot cameras will offer an optical zoom of 35mm to 110mm and then a 2X, 4X or even 8X digital zoom. Your image quality will suffer when you use the digital zoom.
Digital Single-Lens Reflex Cameras (DSLR)
A digital single-lens reflex camera use lenses that have optical zoom only. If you need a different focal length, you need to change lenses. With these cameras you can also use telephoto and wide-angle converters to alter the focal length. Converters are cheaper than new lenses but vary in quality. You can get cheaper ones with plastic elements, but it does not make sense to do that with a Nikon, Canon or other high-quality lens. To maintain the quality, it is better to buy an adapter from your camera manufacturer or third-party quality manufacturer that uses optical glass elements.
Tags: zoom lens, focal length, optical zoom, zoom lenses, digital zoom, point-and-shoot cameras
