Nikon's Coolpix S640 is available for around £180 -- £20 more than its stablemate, the Coolpix S570. But that £20 buys you optical image stabilisation, slightly improved shooting performance and a couple of extra shooting options. Otherwise, it's the same simple and stylish camera, with a wide-angle lens, 5x zoom and consistently very good photo quality below ISO 400. The lack of a high-definition movie mode is a drawback, though. If you're fine with its VGA-only video mode, then the S640 is a decent ultra-compact camera.
Available in silver, white and black, the S640 is a slim, lightweight camera that can be easily slipped into a trouser pocket or small bag. Its metal body gives it a sturdy, high-end feel.
Its lens specifications add to that feel, providing everything you'd want to find in an ultra-compact camera -- it's a 28mm-equivalent wide-angle lens with a maximum aperture of f2.7 and a 5x zoom range. The only disappointment is that, when zoomed out, the aperture goes down to f6.6, making low-light shots iffy when the lens is fully extended. This is slightly more acceptable on the S570, since it's cheaper. You'll also have to be aware of your finger placement when using the flash, as the bulb is located high on the left side and easily blocked.
The controls are fairly standard and easily learned. On top are the power and shutter-release buttons, with a zoom control around the release. On the back, to the right of the bright LCD and below the thumb rest, are buttons for changing shooting modes; playing and editing images; accessing photo, video and system-setting menus; and deleting pictures. There's a dial for quickly moving through settings and photos, and it also acts as a directional pad for navigation and setting exposure, flash, timer and macro. Again, it's all pretty straightforward. The dial moves freely, but there are stops that you can feel when using it. The camera can be charged via a USB cable.
The S640 uses a version of Nikon's four-way 'vibration reduction' image stabilisation, which includes optical image stabilisation. It will also use high ISO settings and shutter-speed adjustments, along with motion detection, to help with handshake and motion blur.
There are 15 scene modes, with nothing out of the ordinary, as well as 'scene auto selector' -- Nikon's automatic scene-recognition mode. Nikon's 'smart portrait system' gets its own spot in the shooting-mode menu. Basically, it combines the previously available 'blink warning', 'smile shutter', 'in-camera red-eye fix', 'D-lighting' and 'face priority AF' features into one mode, and adds a 'skin softening' component. This type of mode is available from other manufacturers, but Nikon's implementation is fast, works well and has a good balance of sharpness and softening.