Canon PowerShot A640

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http://reviews.cnet.co.uk/digitalcameras/0,39030233,49284011,00.htm

Reviewed 16 October 2006

Reviewed by Will Greenwald

With lots of manual settings and a reasonably low price tag, Canon's PowerShot A640 looks quite appealing. Though it lacks the flexibility of higher-end cameras and the stylish portability of more compact shooters, the 10-megapixel PowerShot A640 is a smart, fully featured camera with some surprising benefits.

Design
The A640's most striking feature is its pivoting 64mm (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. 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 48mm thick and weighing 340g, the A640 is 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.

Features
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 more zoom than standard 3x shooters. If the 4x lens isn't enough, the camera accepts additional accessory lenses.

Performance
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 seconds 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.
 

Shooting speed
(Shorter bars indicate better performance)

Typical shot-to-shot time

Time to first shot

Shutter lag (typical)

Casio Exilim EX-Z1000

3.5 

1.8 

0.3 

Canon PowerShot A640

1.7 

1.5 

0.5 

Nikon Coolpix P3

3 

4.1 

0.9 

Image quality
Photos shot at low ISO settings are sharp enough to print well beyond 200x250mm, 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 sparkly, speckled quality beyond the normal grain. Between the noise and the camera's lack of an image stabilisation mode, the A640 isn't the best choice for low-light or high-speed shots.

Beyond the low-light issues, the A640's photos were crisp and detailed. We noticed little fringing or distortion, and fine details showed up quite clearly, especially in the lower ISO settings. Colours tended to appear slightly muted and cool, but otherwise images were very attractive. 
 

A shot taken at ISO 800 with the A640 (top) compared to one shot with the A710 IS (bottom). As you'd expect, the 10-megapixel A640 has the worst noise profile of all the A-series cameras

 
Unfortunately, the A640 preserves the PowerShot's history of less-than-stellar low-light shooting. Otherwise, the Canon PowerShot A640 is a great camera for users who want a solid point-and-shoot with photographer-friendly manual capabilities. If you like the A640's feature set but don't want to spend quite so much for the resolution, you might want to consider the camera's 8-megapixel but otherwise identical little brother, the A630.

Edited by Lori Grunin
Additional editing by Nick Hide