Use optical zoom to make your subject appear close up.
If shopping for a digital camera feels like wading through electronic alphabet soup, don't let advertisements boasting a camera's MP rating, x-factors or inclusion of a CCD or a CMOS get you down. Many of these abbreviations refer to a single, sought-after camera feature: zoom. Compact digital cameras offer two types zoom: optical and digital. Although represented by a smaller x-factor number on the box, optical zoom creates close-up photographs using all the MP -- or megapixels -- available from the camera.
Optical Versus Digital Zoom
Not all zooms are equal. Optical zoom uses the lens, or the optics, of the camera to fill the digital sensor with data. This type of zoom utilizes all of the pixels available to record the image. Digital zoom modifies the image recorded on the sensor by trimming off the edges of the image, then stretching the photo proportionally.
Both digital and optical zoom crop an image, but the resulting photo quality differs. While digital zoom makes the image appear larger, it degrades the quality of the photo since fewer pixels compose the image. As a general rule, only use optical zoom on your digital camera for the highest quality image possible. You can later achieve digital zoom-type results by cropping the photo in photo editing software to make the subject appear closer to the camera.
Explaining X-factors
Digital camera manufacturers rate zoom with an x-factor. Think of the "x" as a multiplier. If the camera has 5x zoom, you can make a subject appear five times closer than you see with the naked eye. If the camera package contains wording such as "5x zoom" or "up to 30x zoom", find out if the numbers refer to optical or digital zoom. Some advertisers will only advertise the zoom type with a larger x-factor to make the camera more appealing.
When using optical zoom combined with an automatic exposure mode on a compact digital camera, the camera automatically adjusts the aperture ring in the camera lens. This adjustment affects the depth of field, or depth of focus visible in the image. As the lens zooms, the aperture ring closes down, allowing less light into the camera. The combination of a longer focal length -- caused by zooming -- and less light causes the depth of field to become shallow. Images captured using the fullest extent of the optical zoom feature often have a soft, blurred background, making the subject appear dominant in the photo.
Megapixels and Optical Zoom
Don't confuse a camera's megapixel rating and optical zoom rating. The amount of megapixels refers to the image size possible from that individual camera. A camera rated at 10MP will offer more detailed images than a 3MP camera.
An optical zoom function will utilize all of the megapixels available for its resolution setting to record your pictures whether you zoom a little or a lot. Optical zoom will not affect the resolution of a picture, unlike digital zoom.
Using Optical Zoom
Only compact digital cameras with built-in lenses offer an optical zoom feature. Single-lens reflex (SLR) interchangeable-lens cameras don't have optical zoom. Many compact digital cameras feature a toggle switch, buttons or a small lever to activate the optical zoom feature. Look for labels such as "T" and "W" on the camera to indicate telephoto and wide-angle views, the two endpoints of a given zoom range. Some cameras use pictorial representations for optical zoom such as a grouping of trees to represent a wide view and a single tree to indicate a close-up view.
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