Canon 1Ds MIII has a
21.0MP Full frame (36 x 24 mm ) sized CMOS sensor . On the other hand, Pentax K-3 II has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Prime III processor.
One other difference between these two cameras that is worth mentioning is that Pentax K-3 II's sensor doesn't have an 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 1Ds MIII and K-3 II sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 1Ds MIII and Pentax K-3 II Cameras
As seen above, Canon 1Ds MIII has a 2.4x Larger sensor area than Pentax K-3 II. 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.
DxOMark Sensor Scores
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 1Ds MIII
80
24.0 bits
12.0 Evs
1663 ISO
Pentax K-3 II
80
23.6 bits
13.6 Evs
1106 ISO
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
Canon 1Ds MIII
or the
Pentax K-3 II ,
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.
