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A megapixel is a measurement of the resolution that a digital camera can produce. A megapixel is equal to 1 million pixels. Pixel is short for picture element, and a pixel is the smallest piece of data a digital camera can record. When the millions of pixels in a digital photograph are aligned, a human's eye only sees the final image, not the minuscule individual dots.
Although many factors affect image sharpness and clarity, resolution is very important. Digital cameras with more resolution, or more megapixels, typically create sharper photos that you can print at larger sizes. To print a sharp 8-by-10-inch photograph, in most circumstances, you'll need to shoot at 6-7 megapixels of resolution.
To help you decide how many megapixels you'll need in a digital camera to meet your photography needs, please click here.
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Digital cameras typically carry two zoom measurements: optical and digital. You essentially can ignore digital zoom, which simply magnifies a section of a photograph the camera has already created. On the other hand, optical zoom measures the camera lens' ability to magnify a scene before you snap the photograph. You don't lose photo clarity and sharpness with optical zoom.
Digital zoom is handy, but optical zoom is the measurement to watch. A 3X optical zoom is the minimum baseline for consumer-level digital cameras.
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Related to optical zoom is the 35mm measurement, which refers to the focal length of a digital camera lens. Digital camera's zoom capabilities often are listed as 35mm-105mm, for example.
A 35mm focal length is considered the standard, with no zoom and no wide angle. The focal length of the lens above 35mm determines the optical zoom measurement. For example, a digital camera lens with a 105mm focal length would be a 3X optical zoom lens versus a 35mm focal length, and a lens with a 350mm focal length would be 10X. A lens with a focal length below 35mm, such as 28mm, would have a wide-angle capability.
To further confuse matters, digital camera manufacturers don't always start at a 35mm focal length when measuring optical zoom. If the digital camera's minimum focal length is 28mm and its maximum is 280mm, for example, it would be listed as a 10X optical zoom lens, even though its maximum focal length would be only 280mm. When shopping, check the focal length measurement to know exactly how much zoom and wide-angle capability you're receiving with a particular digital camera.
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Most digital cameras now include image stabilization (often shortened to IS), which helps prevent camera shake and blurry photos. Two types of IS are available: optical IS and digital IS. Again, optical IS is preferred.
Optical IS uses hardware inside the camera to counteract camera shake. Digital IS, meanwhile, increases the camera's shutter speed and sensitivity to reduce the effects of camera shake. However, digital IS can lead to noise, or stray pixels, in the image. Noise, often a purple fringe on the photo, greatly downgrades image quality.
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ISO speed originated as a measurement of a film's sensitivity to light, and digital cameras have adopted a similar system. When shooting in low-light conditions, you'll need to shoot at a higher ISO speed. Some digital cameras allow you to manually set the ISO speed; others set it automatically. As the ISO speed increases, the image quality decreases.
If you want more control over your camera's image quality, be sure to pick a digital camera that allows for manual setting of ISO speed.
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Addition Aspects to Consider
Some additional aspects to consider when buying a digital camera include shutter noise and camera lag, click here to learn more.