If you've ever discussed digital cameras, inevitably you've heard someone ask "How many megapixels does that camera have?"

There seems to be a perception in digital photography that more megapixels equate to a better camera. While a camera's megapixel count can have a significant impact on image quality, a simple More-Is-Better approach is inadequate. In this article we'll try to understand megapixels, examine why you might want more, and, believe it or not, look at why you might not want more.

Let's begin by defining what a "megapixel" is.

Pixels: Digital Building Blocks

Digital images are made up of a series of dots or squares. If you put enough of the squares together in a small space, then your eye will see a continuous image, not the individual squares. For example, here's a picture of a tortoise from the San Diego Zoo. I've zoomed in on a corner of his shell to reveal the individual squares that make up the image.

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Each of the squares that make up this picture can be considered a "pixel". A megapixel is simply one million pixels. The tortoise picture was shot with a camera that has a 6 megapixel sensor, so the picture contains roughly 6 million of those pixel squares. Understanding megapixels in your digital camera is as simple as that.

Why Is

Having More Megapixels a Good Thing?

More megapixels does not mean a better picture. Having more megapixels does two, and only two, things for you. It gives you the ability to make large prints and it gives you more flexibility in cropping pictures. That's it. Let's look at these two benefits individually.

Large Prints
More megapixels means that you'll be able to make large prints of your photos without seeing any pixels. For example, if you were to make a large 11x14 inch print taken from a 6 megapixel camera, you'd get a nice smooth print. If, however, you tried to make an 11x14 inch print from a 3 megapixel camera, the print would look rough. You'd be able to see individual dots in the 3 megapixel print which would seriously degrade the quality of your picture.

If, however, you were making smaller 4x6 inch prints, the 3 megapixel and 6 megapixel pictures would look just as good, assuming the two cameras were otherwise comparable. For regular 4x6 prints, anything more than 3 megapixels is just overkill and adds nothing to the image quality.

Cropping
If you’ve ever edited your digital pictures on a computer, then you've probably used cropping before. Cropping lets you draw a box around the area of the photo that you'd like to keep. Anything outside the box gets tossed away. This is very useful if you want to eliminate areas of the photo that are distracting - the strange, purple-haired guy who wandered through the background of your family photo, for example.

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