Canon 300D has a
6.0MP APS-C (22.7 x 15.1 mm ) sized CMOS sensor . On the other hand, Canon 40D has a
10.0MP APS-C (22.2 x 14.8 mm ) sized CMOS sensor .
Below you can see the 300D and 40D sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 300D and Canon 40D Cameras
Canon 300D and Canon 40D 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 40D sensors have been tested by DxO and the results show that 40D has a better overall score of 64, 9 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 40D
64
22.1 bits
11.3 Evs
703 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 40D ,
including hyperfocal distance.
