Canon PowerShot A640

The A640's most striking feature is its pivoting 2.5-inch LCD. You can flip and twist it to help frame odd-angled shots or fold it against the camera for a more traditional feel. It's a handy feature, as the screen can tilt up for shooting at chest level, tilt down for shooting over crowds, or even flip all the way around for taking self-portraits. Canon has equipped several of its cameras with this type of pivoting screen, including the A640's lower-end versions, the A630 and A620. The flip-out screen has also been seen in many of Canon's high-end, sub-SLR cameras such as the PowerShot G6 and S3 IS. Curiously, the latest iteration of the PowerShot G series, the G7, lacks the pivoting display. If the display isn't sufficient, the A640 also has a standard optical viewfinder for framing shots the old-fashioned way.

Besides its flip-out screen, the A640 looks like a fairly typical midsize point-and-shoot camera. At 1.7 inches thick and weighing 12 ounces, the A640 is a bit too bulky to just slide into a pocket, but it's perfect for a bag or a jacket. It runs on four AA batteries that fit into a grip on the right side of the camera, giving it a slightly more pronounced curve than most cameras of its shape. The controls are a standard but comfortably placed combination of mode dial, control pad, zoom rocker, and extraneous buttons. The various buttons feel reasonably responsive and easy to find with the thumb, though the tiny record/playback toggle switch's flat shape makes it awkward to manipulate.

The A640 is loaded with features that should please more-advanced photographers. Besides the standard automatic and scene preset modes, the camera offers full PASM controls, giving users the option of completely manual shooting. The camera uses a modest 35mm-to-140mm-equivalent lens, giving it a bit more zoom than standard 3X shooters. If the 4X lens isn't enough, the camera accepts additional accessory lenses. Canon currently offers directly from its site a wide-angle converter lens for $200 and a zoom-boosting telephoto converter lens for $150. We noticed some fairly quick performance in the A640 hindered only by a disappointingly slow burst mode. After a 1.5-second power-up cycle, we managed to take a shot every 1.7 seconds in bright light and once every 2.4 seconds with the flash enabled. Shutter lag was pleasantly low, clocking in at less than 0.5 second between hitting the shutter release and the shot being taken. Unfortunately, the 10-megapixel shooter's burst mode was disappointing; we could shoot only 44 shots over a 34.5-second period, giving us a sluggish frame rate of 1.3 shots per second. In fairness, the camera's high resolution was probably the biggest factor in the slow burst rate; processing 10-megapixel shots takes more time than for 7-megapixel shots.

Photos shot at low ISO settings are sharp enough to print well beyond 8x10, though the camera tends to blow out highlights. Noise starts to appear at ISO 200 but remains a steady and unobtrusive grain up to ISO 400. At ISO 800, however, the noise develops a bit of a sparkly, speckled quality beyond the normal grain. Between the noise and the camera's lack of an image stabilization mode, the A640 isn't the best choice for low-light or high-speed shots.