Casio EX-100 has a
12.0MP 1/1.7-inch (7.44 x 5.58 mm ) sized CMOS sensor . On the other hand, Pentax RZ18 has a
16.0MP 1/2.3-inch (6.08 x 4.56 mm ) sized CCD sensor .
Below you can see the EX-100 and RZ18 sensor size comparison.
Sensor Size and Resolution Comparison image of Casio EX-100 and Pentax RZ18 Cameras
As seen above, Casio EX-100 has a 1.5x Larger sensor area than Pentax RZ18. 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
Casio EX-100
or the
Pentax RZ18 ,
including hyperfocal distance.
One thing to watch when comparing these two: they have different sensor sizes
(1/1.7-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.