Olympus TG-2 iHS has a
12.0MP 1/2.3-inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor . On the other hand, Ricoh G900 II has a
20.0MP 1/2.3 inch (6.17 x 4.55 mm ) sized BSI-CMOS sensor .
Ricoh G900 II's sensor provides 8MP more than Olympus TG-2 iHS'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 TG-2 iHS and G900 II sensor size comparison.
Sensor Size and Resolution Comparison image of Olympus TG-2 iHS and Ricoh G900 II Cameras
Olympus TG-2 iHS and Ricoh G900 II 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. On the other hand, since Olympus TG-2 iHS has 71% larger pixel area compared to Ricoh G900 II, it has potential to collect more light on pixel level hence have less noise in low light / High ISO images.
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
Olympus TG-2 iHS
or the
Ricoh G900 II ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/2.3-inch versus 1/2.3 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.