Why Digital Camera Megapixels Don't Matter

By Kurt Hansen

You see it every time you look at an advertisement for a digital camera. The ad screams 8 MP or 10MP. It looks impressive. It's persuasive. It's important, isn't it? Nope. As a matter of fact, many people don't even know what it means. Many people understand what a 4 cylinder versus a 6 cylinder car means. They might even know what 145 versus 225 horsepower means. But megapixels? Not likely.

The number of megapixels is a measurement of the ability of the camera to capture light and color. A film camera uses film that is exposed to light and color through the camera lens. When the film is exposed, it changes chemically and when processed captures the picture. A digital camera uses an electronic circuit board to capture light and color. This circuit board consists of millions of light and color sensing charge coupled devices (CCDs). That's electronic speak for thingamajig. When the CCDs are exposed to light they capture the picture. Unlike film, digital photos don't need to be processed. They're available immediately.

The CCDs are arranged in an array. Think of it as a checkerboard with millions of squares. The number of squares is calculated by multiplying the number of rows by the number of columns. An 8 MP camera would have around 8 million CCDs. The circuit board might have 3,000 columns and 2,650 rows of CCDs which equals 7,950,000 CCDs. This is close enough for our example to state that it's an 8 MP camera. Each of these CCDs provides a numeric value, called a pixel, for the light and color when exposed by the lens. These values are saved in digital format to create the picture file.

"Doesn't a 10 MP camera capture more and thereby make my pictures better?" you ask. Yes, it captures more pixels. No, it doesn't make your pictures better. "What?" you exclaim. "How can this be? The camera manufacturers keep telling me I need more megapixels. Are they lying to me?" Well, no but they are being a bit misleading. Here's why: resolution determines the quality of the display on your monitor or the quality of a printed picture.

"So now what? How does resolution come into play?" you wonder aloud. Resolution is measured in dots per inch (dpi). It determines how many pixels are needed for a specific size display or print. Digital photos are displayed and printed at specific resolutions. Increasing the resolution will display or print more dots per inch but the image size will go down. Decreasing the resolution will increase the image size but display fewer dots per inch.

Let's say you have a 10MP camera and take photos with the highest number of megapixels. Your camera might produce images of 3,888 pixels by 2,592 pixels. If you multiply these two numbers, the result is just over 10 million or 10MP. Send your pictures over to Walgreens and the standard resolution for printing is 128 dpi. If you want to print an 8 X 10" print you only need ((8 x 128) x (10 x 128)) = 1,310,720 pixels or 1.31 MP. What happens to all of those megapixels? Well, they're wasted! Not needed!

In this example, a camera with the ability to capture 1.31 megapixels will be sufficient to print a quality 8 X 10" print. More megapixels simply allow you to display a larger picture on your computer monitor or print a bigger picture without decreasing quality. That's all megapixels will buy you - bigger pictures.

Camera manufacturers still focus their ads on the number of megapixels. But when buying a camera, don't focus on the number of megapixels. You'd be hard pressed to find a camera with less than 2 MP today. Megapixels are mostly irrelevant unless you want to print or display very large pictures.
Kurt Hansen
http://www.highfxphoto.com
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