Pentax K-3 III has a
26.0MP APS-C (23 x 15.5 mm ) sized BSI-CMOS sensor and features PRIME V processor. On the other hand, Fujifilm S3 Pro has a
6.0MP APS-C (23 x 15.5 mm ) sized CCD sensor .
Pentax K-3 III's sensor provides 20MP more than Fujifilm S3 Pro'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.
Another difference between these two cameras is that Pentax K-3 III's sensor lacks anti-alias (Low-Pass) filter. Removing anti-alias filter increases the sharpness and level of detail but at the same time, it increases the chance of moiré occurring in certain scenes.
Below you can see the K-3 III and S3 Pro sensor size comparison.
Sensor Size and Resolution Comparison image of Pentax K-3 III and Fujifilm S3 Pro Cameras
Pentax K-3 III and Fujifilm S3 Pro 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 Fujifilm S3 Pro has 110% larger pixel area (29.41µm 2 vs 13.95µm 2 ) compared to Pentax K-3 III, it has larger pixel area to collect light hence potential to 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
Pentax K-3 III
or the
Fujifilm S3 Pro ,
including hyperfocal distance.
