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Jan. 26, 2006
If you're new to the digital camera club or searching
for your first digital camera, then you're probably quite confused about the
importance of “megapixels”.
Most salespeople and camera manufacturers lead you to believe that the more
megapixels a camera has, the better. But that's like saying a car with a
bigger engine will go faster than another without taking into account the size
and weight of the car, its transmission, and its aerodynamics. Similar misconceptions
exist about the relationship between megapixels and a camera's image quality.
 For
starters, a camera's megapixel rating is supposed to be based on the active
(or effective) number of pixels on a camera's sensor. (Those are the pixels
that contribute to the color and detail in the final image.) If all things
were equal between two cameras, the one with more megapixels would likely capture
images that were measurably sharper. But all other “things” are rarely equal
between two cameras, and in some cases the difference in megapixel ratings
means absolutely nothing—or worse, it can mislead you into thinking the camera
with the higher megapixel rating has better image quality when the opposite
is true.
The list of factors that contribute to a camera's image quality is
quite long. Here are most of them, not necessarily in order of influence:
• the
design and size of the imaging sensor;
• the camera's image processing
circuits and technology;
• the amount and type of data compression
used to store JPEG files;
• the image quality, contrast, sharpness,
and color settings,
• the accuracy of the camera's focusing, metering,
and white balance systems;
• the quality and focal length of the
lens;
• The time of day and the weather.
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