Nikon D3100 has a
14.0MP APS-C (23.1 x 15.4 mm ) sized CMOS sensor and features Expeed 2 processor. On the other hand, Nikon D40 has a
6.0MP APS-C (23.7 x 15.5 mm ) sized CCD sensor .
Nikon D3100's sensor provides 8MP more than Nikon D40'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 D3100 and D40 sensor size comparison.
Nikon D3100 and Nikon D40 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
Both Nikon D3100 and Nikon D40 sensors have been tested by DxoMark. DxoMark 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. Of the two cameras that we are comparing, D3100 has scored 67, 11 points higher than D40.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Nikon D3100 |
67 |
22.5 bits |
11.3 Evs |
919 ISO |
Nikon D40 |
56 |
21.0 bits |
11.0 Evs |
561 ISO |