Both Canon 300D and Canon 10D have APS-C sized 6.0 MP resolution sensors so sensor size and resolution is not a differentiator between these two cameras.
Below you can see the 300D and 10D sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 300D and Canon 10D Cameras
Canon 300D and Canon 10D 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.
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 10D sensors have been tested by DxO and the results show that 10D has a better overall score of 57, 2 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 10D
57
21.1 bits
10.9 Evs
571 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 10D ,
including hyperfocal distance.
