I May Just Have Figured Out Why My Focus Hit Rate Is Not As High As I Thought It Should Be With My Fujifilm X-T2

This is a 1610 x 1838 pixel crop of the original 6000 x 4000 pixel image (12.3%)  (click to enlarge)
Fujifilm X-T2, 100-400mm f/4.5-5.6mm lens @ 400mm; 1/640th sec. @ f/8; ISO 400

In the past I've written a few posts lamenting that the percentage of "in focus" images made with my Fujifilm X-T2 coupled to the Fujifilm 100-400mm f/4.5-5.6 lens has not been as I as I felt it should have been.  You can read those posts here, here, and here.

Essentially, I was getting quite a few wildlife images (it seems only birds and mammals) that were not in sharp focus even though my technique is sound, my gear is set for high shutter speeds, sufficient depth of field and in many cases, the wildlife was sitting still! 

Dumbfounded by not having this issue with my Olympus E-M1 Mark II, I experimented with changing many parameters, one at a time, to eliminate each variable so as to isolate a specific cause.  Nothing seemed to give me the answer.  Finally, I settled on the fact that the AF mechanism just wasn't focusing well on low contrast feathers and fur.  I had eliminated every other variable and the lens was perfect with other subjects.

Last week, Fujifilm introduced their new X-H1 and from all indications I've seen a marvelous camera in every respect.  While reading FujiRumors.com on February 19th, they published a number of media slides from a Fujifilm presentation.  One of those slides, which were mainly giving comparison figures between the X-T2 and the new X-H1, may have given me the answer I've been looking for.  Here is that slide.

From www.fujirumors.com, showing a performance summary comparison between the new Fujifilm X-H1 and the
current X-T2.  When you have a low contrast/high frequency subject, the success rate of the X-T2's PDAF
autofocusing system, by Fujifilm's calculations, averages 57%. (click to enlarge)

A low contrast/high frequency image would be, of course, one with low contrast but with lots of detail, such as same color feathers on a bird or mono color fur on an animal, such as a deer or bear.  

I guess this graph from Fujifilm gives me my answer as my expectations, evidently, have been too high.  With just over a 50% average hit rate for accurate PDAF focus on this type of target, my images are right in line with that figure.

I would encourage you to look at the other graphs from Fujifilm's media presentation as they highlight some additional improvements to the AF system.  You can find them here.

I'm pleased that with the new X-H1 the figures rise and, hopefully, Fujifilm will bring this improved AF system to the X-T2 and X-Pro 2.  It is nice to know Fujifilm continues to improve their focusing systems as well as other aspects of their cameras and often times, brings those improvements to their existing cameras.

I'm putting this issue to rest as I think I have my answer.

Thanks for looking. Enjoy! 

Dennis A. Mook 

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