Nikon Coolpix S640 review

The most control you get is in the 'program' mode -- called 'auto' on this camera -- which gives you settings for white balance, light metering, ISO, colour options and autofocus. There's also a 'subject tracking' mode for locking focus onto a moving subject, so they're in focus when you're ready to shoot, and a basic movie mode at VGA-quality only, with no use of the optical zoom.

Raises the Coolpix bar
Although the S640's shooting performance isn't outstanding, it's better than we've come to expect from a Coolpix camera, and on a par with the competition. It takes 1 second to power on and shoot. Subsequent shots will leave you waiting an average of 2.4 seconds between them, rising to only 2.7 seconds if you use the flash. Shutter lag in bright lighting conditions is good, at 0.4 seconds. In dim lighting, it's still decent, at 0.8 seconds. The S640 has a full-resolution continuous-shooting speed of 1 frame per second. These are average performance numbers for the S640's class, but it's an improvement for Nikon. They're still not great for moving subjects, though.

Overall, the S640's photo quality is very good. Many cameras in its class suffer a significant dip in quality when they use any sensitivity above ISO 200. The S640 is actually good to ISO 400, although there's some visible noise and increased softness. The camera lets you limit the auto ISO range to either 100-400 or 100-800. Thankfully, its auto ISO only uses up to ISO 1,600. If you're in daylight or bright conditions, we recommend locking it down to 100-400. It performs okay up to ISO 800, but there's definitely increased softness, noise and artefacts.

The S640 can shoot at full resolution up to and including a sensitivity of ISO 6,400. Photos from ISO 1,600 upwards don't look good, though, because of colour shifting and yellow blotching, as well as a near absence of image detail. While you can keep shooting images in low-light conditions, you probably won't be thrilled by the results.

The S640's colours aren't entirely accurate, with it pumping reds and blues up slightly, but the results are pleasing. Everything we shot turned out bright and looked reasonably natural. As is typical of compact cameras, its image highlights tended to blow out, but at least Nikon's D-lighting system helps bring up shadow detail.

For a 28mm-equivalent wide-angle lens, the S640 has little in the way of barrel distortion and no discernible pincushion distortion when the lens is fully extended. In high-contrast areas of photos, there's some purple fringing, but the amounts are below average for its class.

Shooting speeds (in seconds)
(Shorter bars indicate better performance)

Time to first shot

Typical shot-to-shot time (flash)

Typical shot-to-shot time

Shutter lag (dim)

Shutter lag (typical)

Sony Cyber-shot DSC-W290

1.3 

2.7 

2.3 

0.7 

0.4 

Nikon Coolpix S640

1 

2.7 

2.4 

0.8 

0.4 

Canon Digital IXUS 110 IS

1.4 

3.8 

2.6 

0.6 

0.4 

Nikon Coolpix S1000pj

1.8 

2.6 

1.9 

1 

0.5 

Samsung ST550

1.5 

2.6 

2 

0.7 

0.5 

Conclusion
The Nikon Coolpix S640 is just slightly above a basic point-and-shoot ultra-compact. It's not a bad camera, but it doesn't excel in any area. Its shooting performance is improved over other Coolpix cameras, but that only puts it in line with the competition. It does, however, take good photos at ISO 200 and below and, to some degree, ISO 400. Also in its favour is the fact that it's simple to operate and looks and feels good. If you don't want HD-quality movie capture, the S640 is a fine ultra-compact.

Additional editing by Charles Kloet