The Coolpix 3100 appears to use a similar white balance algorithm to other Nikon Coolpix digital cameras, its response was almost identical. In natural light automatic white balance was almost perfect (apart from a very faint pink cast), however in incandescent or fluorescent light there was a strong visible pink color cast. The preset white balances for natural light and incandescent worked well, not so well the fluorescent preset. Thankfully the 3100 has a manual preset option which worked well under any light.
|Outdoors, Auto||Outdoors, Cloudy (or Sunny)||Outdoors, Manual|
|Incandescent, Auto||Incandescent, Incandescent||Incandescent, Manual|
|Fluorescent, Auto||Fluorescent, Fluorescent||Fluorescent, Manual|
The 3100 carries on the strong macro performance of previous Coolpix digital cameras. It's best frame coverage is an amazing 32 x 24 mm at wide angle, however lens barrel distortion and corner softness are both high here and really only the center 50% of the frame is really usable. Zoom to about mid way between wide and tele and you can still get a fairly respectable frame coverage (better than most digital cameras), this delivers no distortion although still fairly high corner softness. The macro tests below are using our new macro focus test chart and measurement system; each line on the grid is 10 mm, taken at shortest subject distance in macro mode.
|Wide angle - 32 mm x 24
63 px/mm (1600 px/in)
Corner softness: High
|Mid zoom - 57 mm x 42
36 px/mm (914 px/in)
Corner softness: High
The A70's internal flash unit has a quoted range of 3.0 m at wide angle and 1.7 m at telephoto (Auto ISO). Our tests showed good color balance but underexposure (poor flash power metering) notably more on our 'normal' skin tone flash shot.
|Skin tone - Natural color, no blue cast, underexposed.||Color patches - Good color balance, no color cast, underexposed.|
The Coolpix 3100 has a dedicate night exposure mode, the 'Night landscape' scene mode. This allows for exposures of up to two seconds, however it also pushes the camera's sensitivity to ISO 400. My experience of taking night exposures with digital cameras is to use the lowest sensitivity, a long exposure and the lens stopped down at least one stop (to avoid softness). As you can see from the sample below the Coolpix 3100 didn't perform well with this combination of high ISO and maximum aperture (softer).
|'Night landscape' exposure: ISO 400, 2 sec, F2.8|
Barrel and Pincushion Distortion
The Coolpix 3100's lens exhibited 1.4% barrel distortion at wide angle (this is above average although considering the small size of the lens system not unexpected) and 0.3% (very low) pincushion distortion at telephoto.
|Barrel Distortion, 1.4% @ wide angle||Pincushion Distortion, 0.3% @ telephoto|
Vignetting / Lens shading
Our vignetting / lens shading test is very simple, a shot
of a blank wall from two meters away, vignetting will always be most visible
at wide angle and maximum aperture and will start to disappear at smaller
apertures and/or further zoom. Kudos Nikon, the 3100 had almost no noticeable
(there is some but it's really so slight as not to be seen) shading at
wide angle and of course nothing at telephoto.
|Hardly any noticeable shading at wide angle and maximum aperture (F2.8)||No noticeable shading at telephoto (F4.9)|
Purple Fringing (Chromatic Aberrations)
Our standard CA test shot taken with the 3100 had virtually no shading however there was a fair amount of blooming emanating from the overexposed areas of the chart. In our everyday shots it was tough to find a clear example of CA, Kudos Nikon.
|Hard to find evidence of CA in everyday shots||Our standard chromatic aberration test shot|
Overall Image Quality / Specific Issues
For most shots the Coolpix 3100 delivered contrasty images with pleasing color and low noise. Nikon appear to have tuned the Coolpix 3100's color response to deliver nice foliage greens, this was noticeable in any shot with leaves or grass. I did find the 3100 to appear slightly softer than other similar three megapixel digital cameras, resolution was average for this level of camera. My only potential gripe would be that I personally found the 3100's tone curve to be a little to contrasty leaving darker areas of the image virtually black, knocking out most shadow detail. It would have been nice to have some control over tone on this camera.
Note: We could not produce our normal noise comparison test because the 3100 does not allow the user to manually select ISO sensitivity.