There is a misconception about digital photography that the more megapixels, the better the image quality. Most people don’t realize that image quality has to do with both the amount of pixels and the size of the image sensor.
The image sensor in a camera is the digital equivalent of film. Light comes through the lens and hits the image sensor, where millions of pixel wells capture what color of light is entering that location. The larger the sensor size, the larger the pixel wells, the more accurate the information. The higher the megapixel, the more pixel wells, resulting in higher image resolution. Do not confuse image resolution with image quality. The size of the image sensor affects the amount of noise, the depth of focus, and the overall sharpness of the image.
In the photos, we see four different sensor sizes. There are currently around ten different image sensor sizes. We also see the difference in image performance based upon sensor sizes. This comparison shows two high megapixel point and shoot cameras and two lower megapixel SLR cameras. All the photos were shot with near identical camera settings at ISO 100. The images using SLR cameras were shot with their normal kit lens, the 18-55mm f/3.5-5.6. Immediately you can see a difference in clarity, noise, and color.
So why should you buy a camera with a smaller sensor?
Well, the smaller the sensor, the smaller the camera. It’s definitely convenient to own a camera which fits in your pocket. Plus cameras with smaller sensors can have much greater zoom lengths in an easy, portable size. Current Point and Shoot cameras are still performing better then current cellphones due to the size of their sensors. Point and Shoot Cameras have sensors varying between 1/2.3-inch and Apple iPhone 5s has a sensor which is 1/3-inch. Plus, Point and Shoot cameras have real zoom lenses. Cell phones use digital zoom, which degrades your image quality.
Realize that the larger the camera you carry, the better the image quality. If you are someone looking for quality, look into SLR cameras. Looking for help finding which camera is right for you? Check this post here.