Sony A550 has a
14.0MP APS-C (23.4 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.
Below you can see the A550 and 550D sensor size comparison.
Sensor Size and Resolution Comparison image of Sony A550 and Canon 550D Cameras
Sony A550 and Canon 550D 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
At Camera Decision, we also look at Dxo Mark sensors when available as we think it is a good indicator of image quality.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Sony A550
66
21.9 bits
11.8 Evs
807 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 A550
or the
Canon 550D ,
including hyperfocal distance.