Fujifilm S3 Pro has a
6.0MP APS-C (23 x 15.5 mm ) sized CCD sensor . On the other hand, Fujifilm S1 Pro has a
3.0MP APS-C (23 x 15.5 mm ) sized CCD sensor .
Below you can see the S3 Pro and S1 Pro sensor size comparison.
Sensor Size and Resolution Comparison image of Fujifilm S3 Pro and Fujifilm S1 Pro Cameras
Fujifilm S3 Pro and Fujifilm S1 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 S1 Pro has 97% larger pixel area (58.16µm 2 vs 29.41µm 2 ) compared to Fujifilm S3 Pro, 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
Fujifilm S3 Pro
or the
Fujifilm S1 Pro ,
including hyperfocal distance.