Digital Cameras: Pixels Aren't Everything


By Stephen H. Wildstrom The folks who market digital gear to consumers like to have a nice, simple number to sell. Computer companies still pitch their newest models on the basis of processor speed, even though that statistic long ago stopped having much meaning for most buyers, who would be hard pressed to tell the difference between a 2-gigahertz Pentium 4 and a 1.2-GHz Celeron. Digital-camera makers are paying the same game, but this time the bait is megapixels rather than megahertz.

Kodak's introduction of the DX4900, a $400 consumer camera with a 4-megapixel sensor, shows that the megapixel war is in full swing. But Nikon's $380 CoolPix 2500 is a 2-megapixel camera that proves that there's a lot more to pictures than pixels.

The pixel count in a digital camera is indeed important, but understanding what it means -- and why more is not always better -- is critical to making an informed choice when looking for a camera that suits your needs. A pixel, short for "picture element," is the fundamental component of a digital image. The more pixels, the more information an image contains and the finer the detail that can be resolved. The equivalent of a pixel in conventional film is a grain of silver halide. It's estimated that a 35-mm frame of fine-grained film such as Kodacolor has the information content of a billion pixels or more.

WASTED INFO. How many pixels you actually need depends on how you plan to use your pictures. For photos put on a Web site or e-mailed to friends or relatives, even 1 megapixel (1 million pixels) is overkill. A full-screen picture at 1,024x768 resolution uses just 786,432 pixels. Supply more than that, and all you do is slow downloads with information that will be thrown away.

Printing is another story, but even there the demand for pixels isn't unlimited. A 2-megapixel image will produce a very good quality 8x10 print. Kodak brags that the DX-4900 can make "stunning prints to 20x30 inches." That may be true, but when did you last make a 20x30 print or even enlarge a quarter of a frame to 8x10 size?

Professional photographers need all the pixels they can get because they make big prints or high-magnification enlargements. Casual photographers, as a rule, do not and will be perfectly happy with a 2-megapixel camera.

STORAGE SHORTAGE. The DX-4900 is a very competent, if not terribly exciting digital camera. Personally, I would have traded some of those pixels for a better lens. The camera offers only a 2X optical zoom, giving a range equivalent to 33-mm to 70-mm lenses on a 35-mm camera. (A 3X digital zoom is also provided, but this is more like an enlargement than true zoom: You trade image quality for size.) The DX-4900 is very simple to use, partly because it offers only a limited range of manual controls.

You do pay a price for all those pixels, however, since the included 16-megabyte CompactFlash storage card can hold only 12 shots at standard-quality settings. (If you want the ultimate in storage, consider SanDisk's new 1-gigabyte CompactFlash card. Of course, at over $700 it costs more than most cameras, but it will hold 750-plus DX-4900 pictures on a single card.)

Uploading your pictures to a Windows PC or a Mac is simple with Kodak's EasyShare system. You set the camera in a tray, press a button, and the pictures are on their way. This system automatically launches software that offers printing on your own printer or on Kodak's commercial service, sharing via e-mail or the Web, and minimal editing functions.

SWIVEL AND SHOOT. While the DX-4900 is about as conventional as a digital camera can get, Nikon's CoolPix 2500 is a somewhat radical design. Closed, it resembles a small tape recorder more than a camera and slides easily into a pocket. To take pictures, a section on the left side of the unit rotates to bring the lens and flash into shooting position.

The design, inspired by Nikon's high-end CoolPix 995, allows you to swivel the lens through an angle of about 90 degrees. This can be a big advantage if you want to hold the camera over you head and shoot downward, as you may when taking pictures at a crowded event. The 3X optical zoom lens gives focal lengths equivalent to 37-mm to 111-mm lenses on a 35-mm camera. The 16-MB CompactFlash card holds 31 standard-quality exposures.

The CoolPix 2500's design forces one serious drawback. It has no optical viewfinder, just a 1.5-inch LCD display. Unlike those on some competitors, this LCD offers very high contrast and brightness, so it's usable even in strong sunlight. But having to rely exclusively on an LCD viewfinder cuts into the rechargeable lithium ion battery's life, which is rated at a relatively short 80 minutes of continuous use.

SUNSET SETTINGS. While the CoolPix 2500 works perfectly well as a point-and-shoot snapshot camera, it offers many of the manual controls that users of Nikon's more expensive digital cameras have come to expect. Very few, if any, cameras in its class provide a manual white-balance setting, which allows you to tailor your picture's color balance for the scene's lighting. More interesting to most likely buyers of this sort of camera are optimized exposure and focus settings for a dozen different types of scenes, including portraits and landscapes, as well as sunsets, snow, and fireworks.

The CoolPix won't quite displace the Canon Digital Elph SA-110 as my pocketable digital camera of choice. For one thing, I really miss the optical viewfinder. But as a solid and versatile midprice camera, it's tough to beat -- even though it has only half the pixels of its competitor from Kodak. Wildstrom is Technology & You columnist for BusinessWeek. Follow his Flash Product Reviews, only on BusinessWeek Online


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