Both Panasonic G3 and Nikon D5100 have 16.0 MP resolution sensors but Panasonic G3's sensor is Four Thirds (17.3 x 13 mm ) and Nikon D5100's sensor is APS-C (23.6 x 15.7 mm ).
Since Nikon D5100's has a larger sensor area with the same resolution, this means that it also has a larger pixel area hence better light collecting capacity for a given aperture compared to Panasonic G3.
Below you can see the G3 and D5100 sensor size comparison.
As seen above, Nikon D5100 has a 1.6x Larger sensor area than Panasonic G3. Larger sensors give photographer more control on the depth of field and blurry background compared to smaller sensor when shot in 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. Panasonic G3 and Nikon D5100 sensors have been tested by DxO and the results show that D5100 has a better overall score of 80, 24 points higher compared to G3's score of 56.
Model |
Overall |
Color Depth |
Dynamic Range |
Low-light ISO |
Panasonic G3 |
56 |
21.0 bits |
10.6 Evs |
667 ISO |
Nikon D5100 |
80 |
23.5 bits |
13.6 Evs |
1183 ISO |