Sigma SD15 has a
5.0MP APS-C (20.7 x 13.8 mm ) sized CMOS (Foveon X3) sensor and features True II processor. On the other hand, Nikon D2Hs has a
4.0MP APS-C (23.7 x 15.5 mm ) sized JFET sensor .
Another difference between these two cameras is that Sigma SD15's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the SD15 and D2Hs sensor size comparison.
Sensor Size and Resolution Comparison image of Sigma SD15 and Nikon D2Hs Cameras
As seen above, Nikon D2Hs has a 1.3x Larger sensor area than Sigma SD15. 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 SD15
or the
Nikon D2Hs ,
including hyperfocal distance.
