Both Nikon D600 and Pentax KP have 24.0 MP resolution sensors but Nikon D600's sensor is Full frame (35.9 x 24 mm ) and Pentax KP's sensor is APS-C (23.5 x 15.6 mm ).
Since Nikon D600's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Pentax KP.
Below you can see the D600 and KP sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D600 and Pentax KP Cameras
As seen above, Nikon D600 has a 2.4x Larger sensor area than Pentax KP. 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
Nikon D600
or the
Pentax KP ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(Full frame versus APS-C),
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.
