Canon 1Ds has a
11.0MP Full frame (35.8 x 23.8 mm ) sized CMOS sensor . On the other hand, Pentax K-1 has a
36.0MP Full frame (35.9 x 24 mm ) sized CMOS sensor .
Pentax K-1's sensor provides 25MP more than Canon 1Ds's sensor, which gives a significant advantage in real life. You can print your images larger or crop more freely.
On the other hand, please keep in mind that Max sensor resolution is not the only determinant of resolving power. Factors such as the optical elements, low pass filter, pixel size and sensor technology also affects the final resolution of the captured image.
One other difference between these two cameras that is worth mentioning is that Pentax K-1'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 and K-1 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 1Ds and Pentax K-1 Cameras
Canon 1Ds and Pentax K-1 have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the same focal length and aperture.
DxOMark Sensor Scores
DxOMark is a benchmark that scientifically assesses image quality of camera sensors. It scores camera sensors for color depth (DXO Portrait), dynamic range (DXO Landscape) and low-light sensitivity (DXO Sports), and also gives them an overall score. Canon 1Ds and Pentax K-1 sensors have been tested by DxO and the results show that K-1 has a better overall score of 96, 33 points higher compared to 1Ds's score of 63.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 1Ds
63
21.8 bits
11.0 Evs
954 ISO
Pentax K-1
96
25.4 bits
14.6 Evs
3280 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
or the
Pentax K-1 ,
including hyperfocal distance.