White Balance

Just like the 8700 the 8400 puts in a very good automatic white balance performance. In natural light white balance is virtually always perfect, under fluorescent light there's a slight cast but it's hardly visible and incandescent which was slightly pink is still considered very good. Kudos Nikon.

Outdoor - Auto WB
Red -0.1%, Blue 0.1%
Fluorescent - Auto WB
Red -0.1%, Blue -3.0%
Incandescent - Auto WB
Red 2.5%, Blue -2.4%

Flash Performance

The Coolpix 8400's flash performance was unsurprisingly almost identical to that of the 8800 (no color cast, slightly under-exposed). The flip-up flash has a specified range of 6.0 m at wide angle and 3.0 m at telephoto which is pretty impressive, although these figures are at automatic ISO sensitivity.

Color chart - good exposure, no color cast Skin tone - no color cast, slightly over exposed

Night exposures

The 8400 has manually selectable long exposure noise reduction which when enabled causes the camera to take a second exposure which is used to subtract noise from the main exposure. The longest manual exposure shutter speed is eight seconds although it is possible to achieve exposures of up to ten minutes via the 'timed release' option on the record menu. Overall results were quite good with virtually no hot pixels even with noise reduction switched off.

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ISO 50, 8 sec, F3.9 (manual exposure), Noise reduction Off
ISO 50, 8 sec, F3.9 (manual exposure), Noise reduction On
ISO 50, 2 sec, F4.2 (manual exposure), Noise reduction On

Macro Focus

As with all recent Coolpix digital cameras the 8400 indicates the optimum macro range (the 'sweet spot') on screen by turning the macro icon and zoom indicator bar green. The best results were achieved at the telephoto end of this 'sweet spot'. As with almost all Nikon digital cameras macro performance was impressive however the corners of the frame were a little soft and there was some obvious barrel distortion.

Wide macro - 61 x 46 mm coverage
53 px/mm (1340 px/in)
Distortion: High
Corner softness: Low (with some CA)
Equiv. focal length: 24 mm
Mid-zoom macro - 46 x 34 mm coverage
70 px/mm (1781 px/in)
Distortion: Average
Corner softness: Average (with some CA)
Equiv. focal length: 37 mm

Barrel and Pincushion Distortion

Despite having an extremely wide angle 24 mm equivalent the 8400 still only produced an 'average' 1.3% barrel distortion which is better than we'd expected. At telephoto we measured 0.2% barrel distortion which wouldn't be noticeable.

Wide angle - 1.3% Barrel distortion
Equiv. focal length: 24 mm
Telephoto - 0.2% Pincushion Distortion
Equiv. focal length: 85 mm

Vignetting / Lens Shading

Our vignetting measurement is made by taking the average luminance value of the darkest corner of the image and comparing it to the average luminance at the center of the image, any difference greater than 15% may be visible in everyday shots. At full wide angle (24 mm equiv.) and maximum aperture the 8400 exhibited quite high lens shading (although the drop-off isn't sudden), you wouldn't immediately notice this in everyday shots but it will affect the overall tone of the scene. Things look better at telephoto with below average shading.

Wide angle, maximum aperture (F2.6)
23.6% maximum fall off, top left corner
Telephoto, maximum aperture (F4.9)
7.9% maximum fall off, bottom right corner
Wide angle, stopped down (F5.1)
13.1% maximum fall off, bottom left corner
Telephoto, stopped down (F6.9)
6.2% maximum fall off, bottom right corner

Purple Fringing (Chromatic Aberrations)

The 8400's wide angle zoom lens put in an impressive performance with essentially no visible fringing even at wide angle and maximum aperture. Kudos Nikon.

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24 mm equiv, F2.6 (max aperture)
34 mm equiv., F5.2

Overall Image Quality / Specific Issues

Considering the adventurous nature of the 8400's lens (24 mm equiv. is very wide for a digital camera) it performed extremely well, good sharpness even in the corners, no purple fringing and relatively low distortion. If you take the lens out of the equation the results were almost the same as the Coolpix 8700, noise levels are very similar, as is tone and color balance (as long as you select Auto saturation). Automatic white balance was good, some of the best among eight megapixel prosumer models. We found no other specific issues which needed further analysis.