Sigma DP2 has a
5.0MP APS-C (20.7 x 13.8 mm ) sized CMOS (Foveon X3) sensor . On the other hand, Nikon D90 has a
12.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor .
Nikon D90's sensor provides 7MP more than Sigma DP2's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
Below you can see the DP2 and D90 sensor size comparison.
Sensor Size and Resolution Comparison image of Sigma DP2 and Nikon D90 Cameras
As seen above, Nikon D90 has a 1.3x Larger sensor area than Sigma DP2. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.
Sensor size sets the circle of confusion, so it drives how much depth of field each
of these bodies gives you at a given aperture. You can calculate it exactly for the
Sigma DP2
or the
Nikon D90 ,
including hyperfocal distance.
