Both Canon 1Ds MIII and Canon 1Ds MIII have Full frame sized 21.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the 1Ds MIII and 1Ds MIII sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 1Ds MIII and Canon 1Ds MIII Cameras
Canon 1Ds MIII and Canon 1Ds MIII 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.
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
Canon 1Ds MIII
80
24.0 bits
12.0 Evs
1663 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
Canon 1Ds MIII ,
including hyperfocal distance.
