Fujifilm Users—There Is An Issue That Results In AF Inconsistencies Of Which You Need To Be Aware

There is potentially a serious autofocus issue with Fujifilm X cameras of which you should be aware.  I had heard references to this issue a few times over the past year but didn’t pay much attention to it since I hadn’t seen anything written about it or heard it discussed on podcasts.  Also, I didn’t seem to have any problems with my X-T4 and lenses.  Or, I thought I didn’t have a problem.  I do.  You may also.  My friend, Rick Walker (The Image Doctors Podcast), first brought this to my attention and advised me of the camera settings with which this occurs. 

ADDENDUM:  Just to be clear as to why I have written this post and the two follow-up post about the autofocus inconsistency issue, I was happy as could be with my Fujifilm gear.  I’ve been shooting with Fujifilm gear since the X-T1 was first introduced.  After I first heard about this problem I just knew I didn’t have any issues as I was happy with my images.  I ignored it.  Only after I heard about this issue three times over a year did I decided to delve deeper into it.  First, I searched the Internet and found comments in forums about the same issue.  That gave it some validity.  Then, I went back into my Lightroom files and pulled up a couple of hundred files and closely examined them.  At first I didn’t see any issues but that was looking at the files I edited.  When I looked at identical files I chose not to edit, that is when I started seeing slight unsharpness.  Some files were sharp and some identical files slightly unsharp.  I guess what I had done was assume the slight mis-focus in some files was my fault and I just chose to edit the best, sharply focused, files.  That’s why it didn’t register that I might have the focus inconsistency issue. That is when I decided to test my camera and my lenses.  What you read and see here are my non-scientific tests of my gear to clearly identify if my gear exhibits the autofocus inconsistency issue.  It does.  I have no idea if this issue is widespread or confined to only a few camera bodies.  That said, I am receiving emails and comments from others who have reached the same conclusion.  Don’t take my word for it.  These posts are for informational purposes only to bring this to the attention of other Fujifilm camera users.  I recommend you test your gear.  Don’t assume your cameras do or do not suffer from the variation in autofocus.  If you read through all three blog posts, you will get a good idea of what the issue is.  Frankly, I hope your camera(s) don’t have the same problem as does mine.

One last thing.  This issue doesn’t seem to affect the medium format GFX system to the best of my knowledge.

a) What is the issue?  b) Which cameras and which lenses are affected?

a) When the Fujifilm camera is set to AF-S with autofocus activated by using the shutter button (not back button AF) and using a wide angle lens generally stopped down, the camera is very inconsistent as to where it focuses.  Repeated focusing on a stationary subject at the same distance will result in wildly different focus distances.  I tested this extensively and I can attest it is happening.  In order to see this you have to enable the AF scale in your EVF and LCD then repeatedly autofocus on the same subject.

b) I don’t know which model cameras are affected but it’s clear the X-T4 is affected.  Any lens that has shorter than 50mm focal lengths seem to be vulnerable to this anomaly.

I tested for this with the 16-55mm f/2.8 lens, 10-24mm f/4 lens and the 55-200mm f/3.5-4.8 lens.  At focal lengths 55mm and longer, I did not see any focus variation.  With focal lengths shorter than 55mm the focusing inconsistency was readily apparent.  In fact, the wider the angle, the worse it was.

For example, I placed a subject at exactly 10 ft. from my camera (mounted on a tripod). With repeated exposures the autofocus varied from 6 ft. to about 11ft. (according to the scale on the LCD).  Very few actually landed right at 10 ft.  This occurred when using focal lengths of 35mm, 23mm and 16mm with the 16-55mm f/2.8 lens.  Also, this variation in autofocusing occurred both at f/2.8 and f/8.  When using the 10-24mm lens on the same subject at 10 ft., at 14mm and 10mm, the focus would vary from 5 ft. to infinity.  Yes infinity when the subject was only 10 ft. away!  Again, this occurred both at f/4 and f/8.

I have extensively tested for this along with some variations of the camera settings (such as using AF-C, Manual focus with “Instant AF”, etc.) and will fully analyze my image files this week.  I’ll have more about this in Friday’s post.

If you have had some wide angle photographs that were not in sharp focus, it may not have been you or a fault of the lens.  It may have been caused by this AF inconsistency issue.

Right now I can say that setting an X-T4 on AF-S, Shutter button autofocus and using a wide angle lens, focus inconsistency can be a problem.  It is with mine and as I look for more info on the Internet I’m finding others that have the same experience.  I recommend you test your own camera and lenses.

Again, more on this on Friday.  

You can find Part II here and Part III here.

Join me over at my website, https://www.dennismook.com.  

Thanks for looking. Enjoy!  

Dennis A. Mook  

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