Canon 90D has a
33.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features DIGIC 8 processor. On the other hand, Canon 77D has a
24.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features DIGIC 7 processor.
Canon 90D's sensor provides 9MP more than Canon 77D'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 90D and 77D sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 90D and Canon 77D Cameras
Canon 90D and Canon 77D 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. On the other hand, since Canon 77D has 34% larger pixel area (13.84µm 2 vs 10.29µm 2 ) compared to Canon 90D, it has larger pixel area to collect light hence potential to have less noise in low light / High ISO images.
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 90D
or the
Canon 77D ,
including hyperfocal distance.
