Nikon A900 has a
20.0MP 1/2.3 (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Nikon P100 has a
10.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor and features Expeed C2 processor.
Nikon A900's sensor provides 10MP more than Nikon P100'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 A900 and P100 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon A900 and Nikon P100 Cameras
Nikon A900 and Nikon P100 have the same sensor sizes so they will provide same level of control over the depth of field when used with same focal length and aperture. On the other hand, since Nikon P100 has 102% larger pixel area (2.81µm 2 vs 1.39µm 2 ) compared to Nikon A900, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
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
Nikon A900
or the
Nikon P100 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/2.3 versus 1/2.3-inch),
so compare them at the same framing rather than the same focal length.
Put the same focal length on the smaller sensor and it will show less depth of
field, not more, because it also crops tighter. The calculator shows the
full frame equivalent focal length for each body so you can match the framing.
