Pentax K20D has a
15.0MP APS-C (23.4 x 15.6 mm ) sized CMOS sensor . On the other hand, Canon 90D has a
33.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features DIGIC 8 processor.
Canon 90D's sensor provides 18MP more than Pentax K20D'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.
Below you can see the K20D and 90D sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K20D and Canon 90D Cameras
Pentax K20D and Canon 90D 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.
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
Pentax K20D
or the
Canon 90D ,
including hyperfocal distance.
