When you're choosing a digital camera, it's easy to spot the ones with big LCD screens and high megapixel ratings. This tells you little about a digital camera's image quality, though.
If you're upgrading from, say, an 8-megapixel digital camera, you'll want something that offers a significant improvement. However, while a 16-megapixel digital camera is tempting, quality is generally worse than with 10-megapixel digital cameras.
To understand why, think about the sensors in these digital cameras. They're about 10mm from corner to corner, but need to measure light at 16 million points. Each pixel is around 1/1,000th of a millimetre wide, and not a lot of light hits something that small. That makes it hard to measure the light accurately. The result is a grainy pattern as the camera tries to hide the noise.
Using fewer megapixels means each pixel on the sensor is a little bigger, capturing more light and measuring it more accurately. That's why enthusiast-oriented compact digital cameras use 10-megapixel sensors. This gives more than enough detail plus less noise than cheaper, higher-megapixel digital cameras. It also helps that these cameras' lenses let in more light. That's indicated by the aperture, such as f/2 or f/2.8, lower figures are brighter