Canon 550D has a
18.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 4 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 77D's sensor provides 6MP more than Canon 550D'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 550D and 77D sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 550D and Canon 77D Cameras
Canon 550D 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 550D has 33% larger pixel area compared to Canon 77D, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
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 550D and Canon 77D sensors have been tested by DxO and the results show that 77D has a better overall score of 78, 12 points higher compared to 550D's score of 66.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 550D
66
22.0 bits
11.6 Evs
807 ISO
Canon 77D
78
23.6 bits
13.3 Evs
971 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 550D
or the
Canon 77D ,
including hyperfocal distance.
