Megapixels: Myth or Reality?

When it comes to technology, more is always better, isn't it? More memory, more hard drive space, more screen resolution. In the case of digital cameras, you keep hearing – from manufacturers, sales people, and friends and family – that more megapixels are the measure of a camera's quality.

But is this true? Or are we being sold a bill of goods? Well, the truth lies somewhere in the middle. Megapixels are an important factor when choosing a digital camera. But they shouldn't be the deciding factor, nor are they the most important.

What's a megapixel anyway?

First off, let's look at what a pixel is. It's short for picture element, and is a single colored square in the mosaic that makes up a photograph. Each pixel represents a bit of light that sensors (explain) in your camera picks up when you click the button to take a picture.

A megapixel is one million pixels – one million little squares of light. In theory, the more megapixels that a camera can pick up, the clearer the photo whether at its original size or when enlarged. Notice that I wrote in theory. Megapixels are just one piece of the photo quality puzzle. There are other factors that influence how good or bad a photo turns out. And they're as important, if not more important, than the number of megapixels that your camera packs.

Megapixels alone don't make a good photo

So, what are some of the other factors that contribute to, or detract from, the quality of a digital photo? They include:

Lighting

Light, or lack of it, has been a problem for photographers from the earliest days of taking pictures. And that still holds true for digital photography. When there's not enough light, photos look dark. When there's too much light, they look washed out.

Using a flash helps, and every digital camera on the market includes a flash as a standard part of the camera. As well, a decent digital camera (or one of better quality) has a number of options that can help to automatically correct any problems that you might have with lighting.

Which brings us to our next factor ...

Size and quality of the camera's image sensor

When you click the button to take a picture, your digital camera collects light using an image sensor. Cameras with higher megapixel counts can take in more light. But that doesn't mean that the quality of the megapixels is greater with an 8 megapixel camera than it is with a 5 megapixel model.

On most cameras aimed at the non-professional photographer, the size of the sensor averages between 0.5 and 0.7 inches. And that's regardless of the megapixel count of the camera. That leads to a problem – as a camera collects more pixels, a lot more light has to be accomodated in a smaller space. Those pixels get smaller and become more densely packed. Smaller pixels are less efficient for gathering light, and millions of them can lead to grainy, poor-quality photos regardless of the megapixel count of the camera.

Lenses

You can argue that a good lens can make a huge difference in the quality of a digital photo. The lens on a digital camera is the gateway to the image sensor. A good lens will let in the right amount of light, and not distort that light or cause photos to become blurry.
With most consumer cameras, you can't change the lens as you can with higher-end digital camera. Still, you can ensure that your digital camera has the best optics available. One feature to look for is an image stabilizer that's built into the lens. This will help prevent blurry photos.

And when using a digital camera, many experts advise turning off digital zoom. Digital zoom works by further homing in one whatever it is you're photographing. That sounds like a good thing, but digital zoom does this by increasing the size of pixels in the photo. And, like the densely packed pixels discusses earlier, this lowers the quality of the photo. You see this as blotchiness or graininess, which is called image noise. And more megapixels, mated with a poor lens and digital zoom, can make the noise worse.

Instead of relying on potentially unreliable digital zoom, try to find a camera with a good optical zoom. Most consumer digital cameras have at least 3X zoom – the ability to zoom in three times closer to your subject. Overall, optical zoom is a better choice because it doesn't degrade the quality of a photo.

How many megapixels are enough?

That's a tough question to answer. It depends on what your needs are when it comes to snapping photos. If you're a casual photographer, someone who takes photos around the house or while on vacation, then you can take great photos with a camera that's in the 5 megapixel to 7 megapixel range. Chances are you, and the folks with whom you're sharing your snaps, won't notice the difference between a photo taken with a 5 to 7 megapixel camera, and one taken with a camera that does double digit megapixels.

Don't believe me? Here are a couple of cases to consider.

In 2007, New York Times technology columnist David Pogue conducted an experiment. He had photos taken with 5 megapixel, 8 megapixel, and 13 megapixel cameras. Pogue then had the photos enlarged to 16 inches by 24 inches, and hung the prints on a wall in New York's Union Station. Out of the dozens of people that Pogue quizzed, only one person was able to tell which photo was taken with which type of camera. The rest could see little or no difference between the various pictures.


My wife has a nice 8.1 megapixel Sony CyberShot camera. In good conditions, that camera takes excellent photos. But I've also taken some lousy shots with it. On the other hand, I've been impressed with the quality of the photos that friends have taken with their cheap cell phones – devices with cameras of less than two megapixels.

Of course, the serious hobbyist and the professional will probably want more megapixels. For photographers who fall into these categories, more megapixels will undoubtedly useful – especially if they're cropping and manipulating their photographs.

Still, the final decision is yours. You're definitely best off with a camera that gives you good resolution, but won't cost you a fortune.

Conclusion

No matter what some people say, megapixels aren't the only factor to consider when buying a digital camera. More megapixels can be useful, especially when resizing or cropping a photograph. With more megapixels, you retain more of the detail and sharpness from the original.

Your best bet is to educate yourself before you buy a digital camera. There are a number of good camera information and review sites on the Web. One of the better ones is Steve's Digicams.

But don't forget to consider the other factors that are discussed in this TechTip. Taken together, they'll help you choose the camera that's right for you.