Fujifilm X-T1 IR has a
16.0MP APS-C (23.6 x 15.6 mm ) sized CMOS X-TRANS II sensor and features EXR Processor II processor. On the other hand, Nikon D300S has a
12.0MP APS-C (23.6 x 15.8 mm ) sized CMOS sensor and features Expeed processor.
Another difference between these two cameras is that Fujifilm X-T1 IR'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 X-T1 IR and D300S sensor size comparison.
Sensor Size and Resolution Comparison image of Fujifilm X-T1 IR and Nikon D300S Cameras
Fujifilm X-T1 IR and Nikon D300S have almost the same sensor size, so neither of them has any significant advantage over the other in terms of providing control over depth of field when used with the 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
Fujifilm X-T1 IR
or the
Nikon D300S ,
including hyperfocal distance.