Autofocus
One element of the X100 we said could be improved was its autofocus, and thankfully this has been significantly developed in the Fuji X100S. As noted in the Features section, the AF system of the new camera is a hybrid type that combines phase and contrast-detection AF, rather than using contrast detection alone. Phase detection is typically the faster system in low light because it does not rely as heavily on good contrast to find focus. The real innovation here is that the 142,000 phase-detection pixels built into the sensor are also used for image capture, so resolved detail is not affected.
With the X100S and X100 set up side by side to record the same scene, there is little difference in the response in bright daylight. Both models are very quick, although the X100S just has the edge. In low-contrast light, however, the difference is noticeable, with the X100S having a faster response and a better hit rate for accurately focused images.
Spot AF can further improve AF accuracy. Any one of 49 areas can be selected, and the spot area set to one of four sizes, with the smallest being very precise.
