The Ins and Outs of Fujifilm X Autofocus

I recently posted an article about getting the most from the Fujifilm X system cameras. One of the points of discussion and contention that came up in the comments was that of autofocus. Other issues, such as flash system and software support were also raised. The flash system is a matter of needs. All manual systems are supported and HSS/TTL is also becoming more fully developed. As for software, although Adobe's support is still in a developing state, speed has increased somewhat, as has detail rendering. Software is mostly now a matter of taste. So, I have decided to address the concerns about autofocus in more detail. 

The Evolution of Fuji Sensors

I was personally introduced to the Fuji X system by a close friend who bought an X-Pro1 and a Fujifilm 35mm f/1.4. At this point, the X-Pro1 was taking multiple seconds just to save a file to card (which of course had to be completed before you could review your images). This was the original X-Trans sensor and processor, both of which were seemingly a proof of concept, rather than a fully fledged system. Autofocus was extremely slow, but a Leica M adapter was released at the same time to allow manual focus M mount lenses to be used. I completely skipped this generation of cameras after trying the X-Pro1, which even after the first couple of Kaizen firmware updates was limited by its hardware.

The next iteration of the sensor, the X-Trans II, was introduced at the beginning of 2013. With its updated processor, it allowed for huge increases in operational speed all around for the cameras that used it, including the X100S, X-E2, X-T10, and the game-changing X-T1. An increase in speed wasn't the only addition, however. The second-generation sensor allowed for much better ISO performance and phase detect autoocus. Whereas the X-Pro1 AF was all but useless in low light, the newer generation was able to focus much more easily, especially when coupled with newer lenses. More on that in a moment.

The next surprise that Fujifilm had in store was Firmware 4.0. The features of this were introduced in the X-T10 and rolled out to the other X-Trans II bodies as time went by. Essentially, this enabled a full-blown tracking system for continuous autofocus and a much improved single focus system. Zone autofocus was also introduced, which allowed older lenses like the 35mm f/1.4 to focus much more quickly in ample light. These were huge improvements that many (myself included) compared to their existing DSLRs. The truth is there was still a lot of wishful thinking involved in those statements. The autofocus was significantly improved and could hold its own in many situations, but it was still not as responsive and well developed as a pro-level DSLR system.

At the beginning of 2016, that began to change. Fujifilm rolled out their latest sensor and processor with the X-Pro2 and then the X-T2. The operational and autofocus speed of these two cameras leaves previous generations in the dust. For the first time, I can honestly say that DSLR manufacturers need to be worried. These little cameras are approaching and in some ways surpassing DSLR territory. A little more on this soon, but let's just say that if Fuji can pull off what they did with Firmware 4.0, that gap will be bridged.

The Evolution of Fuji Lenses

The initial three offerings from Fujifilm were slow and noisy in comparison to their newer lenses. Among the three, the 18mm was relatively the quickest to focus and operate, but the image edges suffered heavily until stopped down to f/5.6 or more. The 35mm f/1.4 rendered beautiful images, but was extremely slow to focus. Finally, the 60mm was optically fine, but again suffered greatly in the autofocus department.

Fujifilm followed these three quickly with some more primes and a collection of consumer-grade zooms. The excellent 14mm f/2.8 was the shining star here, but nothing spectacular was to follow until the standout offerings of the 23mm f/1.4 and 56mm f/1.2. These still suffered from quite slow autofocus (when compared to their DSLR counterparts), especially until the release of Firmware 4.0. Both improved significantly with this update, but still hunted a lot for focus, especially in low contrast situations.

Then came the pro zooms, the 16-55mm and 50-140mm. Both of these were aimed squarely at the working professional as substitutes for their 24-70mm and 70-200mm staples. Although optically spectacular, both still suffered from sluggish autofocus. The linear motor from these was adapted for the 90mm f/2, and finally. we started to see where autofocus was heading with the system.

Come late 2015, we saw the introduction of the first "Fujicron", the 35mm f/2. This tiny lens shows how fast Fujifilm is able to make a lens focus, and the two followups, the 23mm f/2 and 50mm f/2, are no different. These lenses finally put the Fujifilm system right up there with professional-grade DSLRs in terms of focus speed.

The Combination of These

The Caveats

Now that I have sung the praises of the developments Fuji have made in the X system, it is time to be perfectly honest. All of what I have said rings true when there is enough contrast for the system to operate well. In low-light situations, things start to swing back in favor of DSLRs. My Nikon D750 and D800 focus wonderfully, no matter what lens is attached, in next to no light.

I often photograph corporate events in dimly lit hotel function rooms, and although I do this exclusively with Fujifilm X cameras now, I have to be cognizent of their shortcomings. Especially with lenses like the older 56mm f/1.2 or the larger 50-140mm, I need to allow a bit more time (sometimes up to a full second) for the autofocus to lock on before I can make a frame. Looking out for high-contrast edges to focus on really helps with this.

The next is scenes with complex contrast. For example, If a background has patches of light and dark and the subject is moving in and out of those patches (even though the subject is well lit), the X system will struggle. This is especially true when using continuous tracking. The camera will often lock onto the background, even when the subject clearly fills the selected autofocus point.

The final point I wish to make here also relates to continuous focus. Coming from the spectacular Nikon D750, I am used to a camera that locks on instantly and doesn't let go until you release the shutter button completely. The Fujifilm X system takes quite a bit longer to obtain its initial focus, but once it locks on, it also tracks exceptionally well. A burst of 16 frames from both my D750 and my X-T2 got every single frame of my assistant in focus as she ran erratically towards the camera, but the D750 locked on much earlier.

Samples

Below are a few simple, unscientific comparisons between the Fujifilm X-T2 and the Nikon D750. Of course, these are not perfect, as the lenses compared are not perfect matches and lens to subject distances differ slightly due to minimum focus distances. However, these approximate actual conditions that you might use these lenses in and should give you a guide to how well each system performs. Please excuse the rough video; it is for demonstration purposes only. 

Fujifilm X-T2 + 35mm f/2 WR

Nikon D750 + 58mm f/1.4

Fujifilm X-T2 + 56mm f/1.2

Nikon D750 + 85mm f/1.8G

In Conclusion

There are plenty of things to consider when looking at a camera, and autofocus is just one of them. I hope that this article has helped prospective Fujifilm buyers to understand the autofocus system better. As always, I am happy to answer questions and offer further explanation in the comments below. Please also don't hesitate to share your own experiences and thoughts so that we can all benefit and create a larger sample for readers to draw from.