|Nikon D90 offers a fine color reproduction
Color reproduction of the Nikon D90 is fairly consistent and deviates only slightly over the entire light sensitivity compared to the Gretag Macbeth Color Checker. The color reproduction looks fine and extremely natural. Perhaps due to certain colors that are slightly over-saturated, such as blue, red and green. It seems to have a positive influence on the whole reproduction. The auto white balance encounters some difficulties with an abundance of incandescent or fluorescent light. Something we encounter frequently and can be solved easily by using a manual setting. If you use the manual setting on a frequent base, you will obtain a reasonably correct reproduction with the Nikon D90, the entire ISO sensitivity offers a similar result at least to the naked eye. Lab tests show only a minor irregularity at 3200 ISO.
Sensitivity of the image sensor
The actual sensitivity of the image sensor is also measured in the DIWA Lab in order to enable us to compare the specified and actual ISO values. The margins of the differences are usually with a margin of 25%. In the case of the Nikon D90, we find an actual value of 150 ISO (+33%) at 100 ISO. For 200 (125%) and 400 ISO (-26%) we measured 160 and 317 ISO respectively. As for 800 and 1600 ISO they are almost equal to the specified values, however; ISO 3200 (-27%) and ISO 6400 (-11%) deviate strongly. These deviations are common and are used to get a firm grip on the signal/noise ratio.
Signal / noise ratio
Up to and including ISO 400 the signal/noise ratio is excellent to reasonable. From ISO 800 we see the internal noise reduction working hard, which results in a loss of fine details, and from ISO 1600 reasonable detail remains however, drops drastically thereafter. If we compare the signal/noise ratio with the Nikon D300 for example, technical tests show that 3200 ISO on the D300 is around the level of ISO 1000 on the Nikon D90. This is an obvious difference.
|We must draw the conclusion that the ISO level of the D300 is a step too high for the D90. If you shoot in RAW, you will gain more by setting the noise reduction manually.
Dynamic range of the Nikon SLR
The dynamic range is excellent; the Nikon D90 even gets more out of it compared to the D300. The consistent graph shows an excellent to fine result of the D90 up to and including ISO 6400. The Nikon D90 shows some beautiful values, resulting in pictures with fine details in the light and dark areas.
Nikon D90 combined with the 18-105mm zoom lens
The Nikon D90 was tested in the DIWA Lab in combination with the AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR zoom lens. A beautiful lens with a versatile range that has become very popular. A fine range for the consumer to shoot daily moments or portraits. If we measure the sharpness of the centre as well towards the edges, we see an excellent result. Up to and including f/16 the lens delivers a fine result, showing a consistent sharpness at both measurements. As for the range of f/4 - f/8 the AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR zoom lens is at its best.
Nikon AF-S DX Nikkor 18-105mm zoom lens
We did expect distortion, certainly at 18mm (average of +1.21%). Yet the other focal lengths obtain a reasonably fine to excellent result, in particular telephoto range, where hardly any distortion is visible. Perfectionists among us will be able to further improve maximum wide angle, afterwards by software. Nikon is very well able to effectively correct chromatic aberration. Nikon does extremely well in this field with the exception of the telephoto area. DIWA Lab measurements show visible chromatic aberration in the aperture range of f/8 - f/16. The lens performs fine to superb as far as vignetting is concerned. Apart from the 18mm wide angle and full aperture, there is hardly any visible vignetting.