Both Canon 40D and Ricoh GR Digital IV have 10.0 MP resolution sensors but Canon 40D's sensor is APS-C (22.2 x 14.8 mm ) and Ricoh GR Digital IV's sensor is 1/1.7-inch (7.44 x 5.58 mm ).
Since Canon 40D'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 Ricoh GR Digital IV.
Below you can see the 40D and GR Digital IV sensor size comparison.
Sensor Size and Resolution Comparison image of Canon 40D and Ricoh GR Digital IV Cameras
As seen above, Canon 40D has a 7.9x Larger sensor area than Ricoh GR Digital IV. 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.
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 40D
or the
Ricoh GR Digital IV ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(APS-C versus 1/1.7-inch),
so compare them at the same framing rather than the same focal length.
Put the same focal length on the smaller sensor and it will show less depth of
field, not more, because it also crops tighter. The calculator shows the
full frame equivalent focal length for each body so you can match the framing.
