Canon 300D has a
6.0MP APS-C (22.7 x 15.1 mm ) sized CMOS sensor . 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.
Canon 550D's sensor provides 12MP more than Canon 300D'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 300D and 550D sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 300D and Canon 550D Cameras
Canon 300D 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
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 300D and Canon 550D sensors have been tested by DxO and the results show that 550D has a better overall score of 66, 11 points higher compared to 300D's score of 55.
Model
Overall
Color Depth
Dynamic Range
Low-light ISO
Canon 300D
55
21.0 bits
10.8 Evs
544 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
Canon 300D
or the
Canon 550D ,
including hyperfocal distance.
