Digital camera buyers should avoid the megapixel madness

March 18, 2004|By MIKE HIMOWITZ

THIS IS THE season when people begin planning their summer vacations, and judging from questions I'm getting, a lot of them plan to take digital cameras along this year.

Folks who bought 3-megapixel cameras last year want to know if they should upgrade. And for snapshooters who are buying their first camera, the big question always seems to be, "How many megapixels do I need?"

The answer is not to get caught up in megapixel mania. To understand why, it helps to know how digital cameras work.

Instead of recording on film, digital cameras focus the image on a light-sensitive electronic plate known as a charge-coupled device, or CCD. The CCD breaks the image into a grid of tiny dots, or pixels. Each pixel has a color value, which typically is expressed as a number in binary form. The camera transfers those numbers to the memory card as part of a digital image file.

Once you've transferred the file to a computer, your photo-editing software turns it back into an image that can be displayed, edited and printed. You also can send the file to someone else via e-mail or post it on a Web site.

The resolution of a camera is the number of pixels recorded by the CCD. The more pixels a camera uses to record an image, the greater the detail, or resolution.

Resolution is measured by multiplying the number of horizontal and vertical pixels, which usually comes out in the millions. Each million is known as a megapixel. So a camera that records photos 1,600 pixels wide by 1,200 pixels high will have a resolution of 19.2 million pixels, or about 2 megapixels.

Likewise, an image of 2,000 by 1,500 pixels is referred to as a 3-megapixel image. An image of 2,400 by 1,800 produces a 4.2 -megapixel image, and so forth.

Why wouldn't you want the highest-possible resolution? First, it's expensive. Typically you'll pay hundreds of dollars more for a 5-megapixel camera than you will for a 3-megapixel model with similar features.

Second, you may not need it. If you're just snapping photos of the kids to send to grandma and grandpa via e-mail, you're not doing them any favors by sending a huge image. All they want is a glimpse of your offspring - unless they're digital photo mavens, they're going to be viewing the photos in their e-mail program or a Web browser. A large photo will overwhelm the screen.

Resolution does, however, count when you print a photo, particularly if it's cropped. Printers have much higher resolution than computer monitors - often measured in thousands of dots per inch. So the more detail in your image, the better your prints will look - but only up to a point.

For example, a 2-megapixel image will produce a good 4 x 6-inch print, and possibly a decent 5 x 7. A well-exposed 3-megapixel image will produce a good 5 x 7 and possibly an 8 x 10. I'm not talking about a print that's merely recognizable, but a sharp one with true colors that looks like a photofinisher's work.

Since most printers won't deliver anything larger than an 8 1/2 x 11-inch image - and relatively few photographs warrant even that size - a 3-megapixel camera is fine for snapshots and occasional enlargements.

But there's a hitch when you decide to crop an image, because cropping eliminates pixels. For example, if you crop out half of a 3-megapixel image, you're down to a 1.5 megapixel image, which is marginal for anything but a snapshot.

That's why experienced photographers will tell you that the first rule is to compose your pictures carefully and fill the frame with your subject - whether you're using a digital camera or film. But it's a rare snapshooter who composes photos perfectly.

So, if you want to cover all the bases, a 4-megapixel image will produce superb snapshots and fine enlargements, even with some cropping. If you're shooting sports from a distance or vacation landscapes that might require even more cropping, a 5 megapixel camera might be worth the money.

If your budget is limited, however, the key is finding the camera that produces the best original photo, which isn't necessarily the one with the highest resolution. Most manufacturers offer two or three lines of cameras, each with a choice of resolutions. The more expensive lines typically have better lenses that make sharper pictures, more powerful flashes (or a shoe for an external flash), and a variety of exposure adjustments. You might get superior results overall choosing a better camera with slightly lower resolution than with a lower-end model with higher resolution.

Finally, by being a smart photographer, you can make huge improvements in your images at any resolution.

For example, the CCDs in all but the most expensive digital cameras aren't as sensitive to light as the all-purpose, ISO 400 speed film that many traditional photographers use. And zoom lenses lose light-gathering ability when extended. The camera typically compensates by decreasing the shutter speed, which in turn increases the effect of camera shake. The result is often a blurry image. Using a tripod or monopod, or even steadying your camera against a post or fence, can work wonders.

Digital cameras also have more trouble handling high-contrast lighting than film cameras. So using a fill flash to open up the shadows when shooting people outdoors can produce remarkably better photos. Indoors, unless the room is dark, you might have better luck with a tripod and available light than the camera's puny flash.

Bottom line: Spend your money on the best combination of resolution and features. You'll be a happier photographer.

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