In the beginnings of Fujifilm’s revival, their cameras weren’t known for their great AF system in terms of both speed and accuracy. Many firmware later, Fujifilm has significantly improved the situation with both firmware and better lens focusing systems. But it’s not perfect yet. Even today, sometimes there is is some AF hunting.
- The AF point is too small and therefore can’t find enough contrast to focus on.
- The AF point is positioned on a spot without sufficient contrast.
- The light levels are too low for the phase detection system and the original lenses.
- Very low available light.
Modern Fujifilm cameras have 2 focusing systems: CDAF (Contrast Detect AF) and PDAF (Phase Detect AF). The center of the sensor has the Phase Detect sensors which is as much as 10 times faster than the Contrast Detect sensor which as much slower but more accurate.
The Phase Detect AF doesn’t work when:
- The lens aperture is set to: > f/9
- There isn’t enough light: < 1EV
- The single point AF used than isn’t located in the PDAF grid.
- An AF zone that includes some non-PDAF sensors in the Zone.
- The AF mode is wide/tracking AF.
With the same lighting conditions and the same lenses, the newer cameras with the X-Trans III will hunt a lot less than the cameras with the X-Trans II who in turn will hunt a lot less than the X-Trans cameras.