Canon 1Ds MIII has a 21.0MP Full frame (36 x 24 mm ) sized CMOS sensor . You can shoot at maximum resolution of 5616 x 3744 pixels with aspect ratios of and 3:2. 1Ds MIII has a native ISO range of 50 - 3200 and it can save files in RAW format which gives you a wider room for post processing.
Canon 1Ds MIII is not the highest resolution Full frame camera. Blackmagic PYXIS 12K with its 98.8MP sensor is leading in this class. Check the comparison of Canon 1Ds MIII vs Blackmagic PYXIS 12K or take a look at Highest resolution DSLR cameras list.
Canon 1Ds MIII DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. Canon 1Ds MIII sensor has been tested by DxO Mark and got an overall score of 80 for its image quality. You can find the details of their analysis of Canon 1Ds MIII here.
Let's look at how the size of the Canon 1Ds MIII's Full frame sensor compares with other standard sensor sizes.
Comparison image of Canon 1Ds MIII Sensor Size with other standard sensors
Sensor size is what determines the circle of confusion, and therefore how much
depth of field Canon 1Ds MIII gives you at any given aperture.
You can
calculate
the exact depth of field for the Canon 1Ds MIII
at any focal length, aperture and subject distance, including the hyperfocal distance
for landscapes and the very shallow focus zone you get with long telephoto lenses.
