Canon 70D has a
20.0MP APS-C (22.5 x 15 mm ) sized CMOS sensor and features Digic 5+ processor. On the other hand, Sony A77 has a
24.0MP APS-C (23.5 x 15.6 mm ) sized CMOS sensor and features Bionz processor.
Below you can see the 70D and A77 sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 70D and Sony A77 Cameras
Canon 70D and Sony A77 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
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 70D and Sony A77 sensors have been tested by DxO and the results show that A77 has a better overall score of 78, 10 points higher compared to 70D's score of 68.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 70D
68
22.5 bits
11.6 Evs
926 ISO
Sony A77
78
24.0 bits
13.2 Evs
801 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 70D
or the
Sony A77 ,
including hyperfocal distance.
