Nikon Coolpix S640 Performance, Timings, and Image Quality

PERFORMANCE
Nikon claims the S640 is the quickest Coolpix ever - with the fastest start up time of any currently available camera in its class and an auto focus system that is as speedy as many entry level DSLRs. The S640's performance is impressive, especially so for an ultra-compact, but it is no speed demon. Here's the problem (granted it isn't much of a problem): the camera starts up almost instantly, but users then must wait 2-4 seconds before the camera can/will do anything - menu access, zooming, review, image capture.

Shutter Lag (press-to-capture, pre-focused)

AF Acquisition (press-to-capture, no pre-focus)

Continuous Shooting

After the camera is fully awake it is pretty quick, but not noticeably quicker than its competition - Shutter lag is 0.04 seconds, and AF Acquisition is a very snappy 0.29 seconds. The S640's continuous shooting mode (which allows users to capture several images in quick succession) is 3 frames in 2.2 seconds. Shot to shot times also seem a bit quicker than average.

Shooting Performance
In addition to being quicker than most of the competition the S640 consistently produces sharply focused and properly exposed images even in lighting that would challenge most point and shoots. The S640 accomplishes this by way of the camera's triple threat Image Stabilization system. It consists firstly of Nikon's standard Vibration Reduction technology, which works by quickly and precisely shifting lens elements in the S640's Nikkor zoom to compensate for camera movement during exposure. Digital Image Stabilization boosts sensitivity (up to ISO 6400) and increases shutter speeds to help further counter shooter instability - especially in low light. Nikon's Motion Detection technology automatically (when needed) manages shutter speed and sensitivity to compensate for minor subject movement during exposure.

The S640's VR system provides only two options - on or off. Finally, Nikon's nifty BSS (Best Shot Selector) mode captures (in rapid sequence) up to 10 shots of the subject and automatically saves the sharpest frame - so even in dismal lighting the S640 produces good images. Not only is the S640 a pretty good "street" camera it also turns out to be a decent indoor/bar/party camera.

Nikon claims the S640's AF is as speedy as many entry-level DSLRs - which is interesting since Contrast Detection type AF systems like the one used by the S640 are generally slower than the phase detection AF systems used in most DSLRs. I didn't have an entry level DSLR on hand to compare with, but the S640's AF is very quick and dependably accurate.

The Coolpix S640's built-in multi-mode flash is a bit on the weak side, but it provides an adequate selection of artificial lighting options, including Auto (fires when needed), On (fill flash), Red-Eye Reduction, Slow Sync, and Off. Nikon claims the maximum flash range (auto ISO) is about 25 feet, but that distance (based on my admittedly very limited flash use) seems wildly optimistic.

The S640 is powered by a 3.7V, 1050mAh Nikon EN-EL12 lithium-ion battery. Nikon claims the S640 (with a fully charged battery) is good for 270 exposures. I do a lot of shoot, review, delete, and re-shoot so I can't really keep track of exposures - but I only charged the battery twice while I had the camera. The supplied Charging AC Adapter (EH-68P/EH-68P) charges the battery in-camera.

The S640 provides 45MB of internal memory and stores images to SD/SDHC memory media up to 16GB.

Lens Performance
Most ultra-compact digicams sport 3x zooms, so one of the nicest features of the S640 is its very good f/2.7-6.6, equivalent 28mm-140mm 5x Nikkor zoom. Starting at a wide angle equivalent of 28mm is impressive, since most ultra-compact digicam zooms start at around 35mm. The S640's lens makes this camera very useful for candid/street shooters because they not only get a little extra width, they also get a little extra reach. This lens has a fairly fast maximum aperture at the wide end but a very slow maximum aperture at the telephoto end of the zoom range.

When the camera is powered up, the lens automatically telescopes out of the camera body. When the camera is powered down, the lens is fully retracted into the camera body and a built-in iris style lens cover protects the front element. Center sharpness is pretty good overall, but at the wide-angle end of the zoom corners are slightly soft. I didn't notice any vignetting (dark corners) and both barrel distortion (straight lines bow out from the center) and pincushion distortion (straight lines bow in toward the center) seem well corrected. Contrast is balanced and colors are hue accurate. Minimum focusing distance (in Macro mode) is 0.8 inches. Zooming is smooth, silent, and quick.

Video Quality
The Nikon Coolpix S640's movie mode is competent, but unexciting and pedestrian - it allows users to capture video clips with monaural sound at resolutions of either 640x480 at 30fps or 320x240 at 15fps. There is no HD mode - with HDTVs proliferating like proverbial bunnies, an HD video mode is becoming something of an expected feature on newer digicams. Shooters can't use the optical zoom (although the optical zoom can be set to whatever length is desired prior to recording) during video capture, but the digital zoom can be used.

Image Quality
Like most point and shoots, the S640's images are optimized for the bold, bright colors, and balanced contrast that many veteran shooters refer to as consumer color - overall color is accurate but noticeably over-saturated. Reds are very warm, blues are bold and bright, and greens/yellows are overly vibrant. Unlike the vast majority of compact cameras, the S640 does a very good job of accurately rendering purples.

Outdoors, the S640 does a great job - image quality is dependably excellent. Exposures are consistently accurate, but lots of sky in the picture often results in slightly overexposed images.

Nikon Coolpix S640

Fujifilm FinePix F70EXR

The S640's Auto White Balance is dependably accurate over a wide range of lighting conditions. In fact, it's the best auto WB I've seen in a camera in this price class - easily equal to Canon's "G" series cameras. The S640's Auto WB mode handled indoor color with aplomb - I had color accuracy problems under mixed indoor lighting with the Nikon Coolpix S620, so clearly Nikon has tweaked their white balance color interpolation a bit for the S640.

Auto White Balance, 3200k incandescent light

In addition to the auto setting there are Manual, Daylight, Incandescent, Fluorescent, Cloudy, and Flash settings.
Indoor image quality is excellent, on par with much more expensive digicams, but as sensitivity automatically rises to overcome lower levels of ambient lighting, noise rises exponentially and color accuracy suffers a bit. Noise levels are quite reasonable up to ISO 400, but they increase substantially after ISO 800.

ISO 100	ISO 100, 100% crop
ISO 200	ISO 200, 100% crop
ISO 400	ISO 400, 100% crop
ISO 800	ISO 800, 100% crop
ISO 1600	ISO 1600, 100% crop
ISO 3200	ISO 3200, 100% crop
ISO 6400	ISO 6400, 100% crop

Additional Sample Images