How much is thin worth to you when it comes to digital cameras?

There's no question that thinner cameras look sexier than their bulkier competitors. These engineering marvels, under an inch thick, are also easier to tote around, ready at hand in pocket or purse without being in the way. But that added style and usefulness can come with their own trade-offs.

Price, somewhat surprisingly, isn't the biggest among them. Among the 10 digital cameras we tested, the thinner models cost only about $90 more. For that, you'll get a camera that not only is noticeably thinner -- for example, the Canon PowerShot SD400 (about $380 in stores) is half as thick as the $230 PowerShot A520 -- but is lighter and sleeker, sized to easily slip into a pocket.

Nor is picture quality something that must be sacrificed in a smaller digicam. We cannot report any consistently significant difference in the quality of images from these two categories. Like their larger counterparts, pocket-sized digital cameras now all incorporate such must-haves as an optical zoom lens and three or more million pixels (megapixels) of resolution.

Batteries, however, can constitute a major compromise. Most ultra-thin cameras must employ expensive, proprietary rechargeable batteries that you won't find outside of camera stores -- Sony Corp.'s hyper-sexy Cyber-shot DSC-T7, only 0.6 inch thick even where the LCD cover protrudes, is itself thinner than the rechargeable AA batteries that power its thicker sibling, the DSC-S90. And when one of these unique batteries runs out, you'll need a spare or ready access to an outlet (you did remember to pack the charger, right?).

All mid-range cameras offer both optical viewfinders (windows to look through that frame the picture) and color display screens, but some ultra-small models omit the viewfinder. We prefer to have both options, with the display as large as possible -- good examples being the weather-protected, 2.5-inch screens on Pentax's thin Pentax Optio S5Z and thicker Optio S55. Similarly, many compact models may disappoint more ambitious photographers by not offering manual control of such factors as aperture and exposure times, instead providing simpler, automated scene-specific options.

Usability can and should be the biggest factor in choosing any camera. An electronic device can be too small; just try to punch in a phone number on a new cell phone. Some ultra-thin cameras would present a challenge for the large-fingered among us. For example, the otherwise excellent Kodak EasyShare V550's on/off switch is tiny and kept flush with the camera's surface, making it hard to switch on in a hurry.

This is why digital cameras, like computer keyboards and monitors, should not be purchased without a hands-on trial. Inspect some cameras, hold them, take pictures with them, see how they feel in your hands and where your fingers fall on its controls. Choose the most compact and convenient camera that works for you and feels comfortable. But if a camera feels too small, leave it behind.