Canon 20D has a
8.0MP APS-C (22.5 x 15 mm ) sized CMOS sensor . On the other hand, Canon 70D has a
20.0MP APS-C (22.5 x 15 mm ) sized CMOS sensor and features Digic 5+ processor.
Canon 70D's sensor provides 12MP more than Canon 20D'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 20D and 70D sensor size comparison.
Canon 20D and Canon 70D 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 20D has 143% larger pixel area compared to Canon 70D, 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 20D and Canon 70D sensors have been tested by DxO and the results show that 70D has a better overall score of 68, 6 points higher compared to 20D's score of 62.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Canon 20D |
62 |
21.9 bits |
11.0 Evs |
721 ISO |
Canon 70D |
68 |
22.5 bits |
11.6 Evs |
926 ISO |