Both Nikon D3100 and Pentax Efina have 14.0 MP resolution sensors but Nikon D3100's sensor is APS-C (23.1 x 15.4 mm ) and Pentax Efina's sensor is 1/2.3-inch (6.17 x 4.55 mm ).
Since Nikon D3100'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 Efina.
Below you can see the D3100 and Efina sensor size comparison.
Sensor Size and Resolution Comparison image of Nikon D3100 and Pentax Efina Cameras
As seen above, Nikon D3100 has a 12.7x Larger sensor area than Pentax Efina. 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 D3100
or the
Pentax Efina ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(APS-C 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.
