Canon's S30 and S40 cameras fill a gap in the company's digital lineup. Nestled between the ultra-tiny Elph models and the feature-packed PowerShot G and Pro models, the S30 and S40 combine most of the portability of the former with nearly every advanced feature of the latter.

With the exception of their CCD sensors (the S30 is a 3-megapixel model, while the S40 is 4-megapixel), the cameras are essentially identical. Each features a brushed aluminum body with a sliding clamshell lens cover, a 3x optical zoom Canon lens, and a 1.8-inch LCD on the back of the camera for previewing and reviewing shots.

For beginners, the cameras are point-and-shoot simple. Just twist the dial to Auto and start snapping pictures. For more experienced photographers, both models include aperture priority, shutter priority, and full manual modes, plus manual focus, exposure compensation, slow-sync flash, spot metering, and adjustable ISO (from 50 to 400 on the S40, and 50 to 800 on the S30).

Movie mode lets you capture video clips with sound. At 320 x 240 or 160 x 120 pixels, the movies aren't camcorder quality, but they're fun and convenient, and they're perfect as e-mail attachments. The cameras also include an unusual voice-memo feature, which lets you record up to 60 seconds of audio with each image.

To provide maximum battery life in the smallest possible space, the cameras use a proprietary lithium-ion battery (both the battery and a charger are included). The battery charges quickly and holds a reasonably long charge, but if you're planning to use the camera for extended outings, a spare battery is a good idea. A larger-capacity memory card is also advisable if you want to shoot more than a dozen photos at a time or really take advantage of the movie mode. The cameras use Type I or Type II CompactFlash cards, including the Microdrive. To print your photos at home, the S30 and S40 connect directly to Canon's CP-10 and S820D printers for easy printing--you don't even need a computer.

If you're looking for a camera with the sleek, compact style of a point-and-shoot with the extensive manual controls of an advanced amateur camera, the S30 and S40 are both great choices.