Sony A77 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz processor. On the other hand, Canon 550D has a
18.0MP APS-C (22.3 x 14.9 mm ) sized CMOS sensor and features Digic 4 processor.
Sony A77'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 A77 and 550D sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A77 and Canon 550D Cameras
As seen above, Sony A77 has a 1.1x Larger sensor area than Canon 550D. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in same focal length and aperture.
DxOMark Sensor Scores
Both Sony A77 and Canon 550D sensors have been tested by DxoMark. DxoMark 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. Of the two cameras that we are comparing, A77 has scored 78, 12 points higher than 550D.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A77
78
24.0 bits
13.2 Evs
801 ISO
Canon 550D
66
22.0 bits
11.6 Evs
807 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
Sony A77
or the
Canon 550D ,
including hyperfocal distance.
