Photograph: Rick Rizner

Casio's $399, 5.1-megapixel EX-S500 may be one of the thinnest zoom-lens-equipped digital cameras you can buy--just 0.6 inch front to back with its 3X zoom lens retracted. That makes it small enough to take with you almost anywhere. Casio offers this model in three colors: dark gray, white, and an eye-catching orange. The 2.2-inch LCD is slightly smaller than the 2.5-inch displays found on some competing models of comparable size, but it's perfectly adequate for composing shots or sharing snaps with friends. The EX-S500's small size and large LCD does mean that you'll have to forgo the luxury of an optical viewfinder.

The EX-S500 starts up in less than 2 seconds and has minimal shutter lag. At first glance, its stylish controls suggest a victory of form over function. But though the buttons are tiny, I found them surprisingly simple to use. Menus are easy to navigate, too, and that's a good thing, since almost all of this camera's controls--including the macro setting, self-timer, and white balance--reside in them. You can, however, set the right and left keys on the four-way thumb pad to launch your most frequently used controls, such as exposure value (the default), focus, ISO, self-timer, or white balance. Oddly, there is a dedicated button for voice recording.

Casio includes 29 scene modes for you to choose from when you press the dedicated "Best Shot" button; each is illustrated with a sample image and a short description. An antishake feature helps keep shots sharp for long exposures or in low-light conditions. You can adjust settings for sharpness, saturation, and contrast, as well as flash intensity. A small window onto your current subject immediately displays the effects of menu settings such as white balance and exposure compensation.

On the negative side, though the S500 includes an SD Card slot, it doesn't come with media; the paltry 8.3MB of internal memory is enough for only two shots at the camera's highest quality setting. I had some difficulty zooming precisely, and the instant review of each shot is so fleeting that you barely have time for a glance before it disappears.

In our formal testing, the S500 earned average scores for exposure and color accuracy. The details in our resolution test, however, were noticeably less sharp than for other recently tested 5-megapixel cameras. There was also a significant amount of noise (or speckling) in solid colors. On a sunny day, I took the camera on a walk along the San Francisco waterfront, capturing some lively and colorful scenes. My portraits were especially good. On the other hand, the camera's limited aperture range made it harder to capture composite shots with both the near foreground and distant background in focus.

At home or in the office, the S500 perches on its small docking cradle, facing rearward. You can set it to display a calendar, with each day you took a photo represented by a small thumbnail image. Alternatively, you can arrange for it to run a slideshow while charging its lithium-ion battery. When traveling, you must take both the cradle and the compact power adapter with you; the only connector on the camera is for slotting it into the cradle. In our tests, the battery completed a reasonable 261 shots on a single charge.

Upshot: The ultrathin Casio Exilim EX-S500 is a quick, easy-to-handle camera best suited for snapshots of family and friends.

Paul Jasper