Nikon P610 has a
16.0MP (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Nikon A900 has a
20.0MP 1/2.3 (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Below you can see the P610 and A900 sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon P610 and Nikon A900 Cameras
Nikon P610 and Nikon A900 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.
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 P610
or the
Nikon A900 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
( versus 1/2.3),
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.