What is the difference between a high-pixel camera and a low-pixel camera?

Answer 1

In general, higher Megapixels (MPs) are better if the pixel size is not reduced. So the sensor size needs to increase proportionately with the number of MPs. Why? Because a reduced pixel will gather less light, hence will be more noisy (poor signal to noise ratio). That inevitably leads to poor dynamic range (range of captured brightness levels). Nevertheless as the technology of manufacturing and data processing improves, it is possible to cope with incremental reduction in pixel size while holding on to image quality. e.g. jump from 7 to 8MPs on same sensor area. In general higher pixel camera will facilitate larger print size (all else being equal). For lab quality 8"x10" print (at 300DPI), at least 7.2Megapixels will be required.

In practical terms, the type of picture desired dictates the number of MPs required. For studio-quality A4-size portraits or close-ups, especially wedding photos, you need a high-pixel camera . At the other extreme, if you just want to take snapshots of friends at parties, then only a low-pixel camera is needed: 5MP would be sufficient.