Fujifilm Focusing Issues in the Fujifilm GFX100 Have Existed for At Least 6 Years in Fujifilm X Series Also
Related: Craig E, focusing, Fujifilm, Fujifilm APS-C, Fujifilm GFX100, Fujifilm medium format, Fujifilm mirrorless, Glenn K, medium format, reader comment, unstable lens focus
Craig E writes:
As a landscape photographer, I am deeply interested in your ongoing Fujifilm GFX100 testing. Last year, I purchased a Fujifilm XT-30 for the sole purpose of time-lapse photography. After minimal testing, I drove into the wilderness 80 miles and set up the camera, fully enclosed in a steel case. Manual focus, with focus ring taped with gaffers.
A week later I returned, and found that focus had changed sometime during the first night. What I have learned is that switching the camera menu to M, and setting the lens switch to M (if the lens has a switch) is not enough to stop the camera from changing focus.
I’m not sure if there is one or even 3 settings to successfully shut down AF—I went through the menu and turned off everything af related—and I now have a fully manual focus camera. But!—only if I have the shutter button set to focus—if I set the camera to back button focus, the camera autofocuses with the body set to MF. It is all very weird. I have owned several Fujis and always want to love them, but never do.
DIGLLOYD: in my experience with Fujifilm cameras, setting the camera to manual focus does nothing for focus stability; the unstable lens focus behavior persists, which is awful for some shooting scenarios. See Fujifilm GFX100: Unstable Lens Focus for what can be done to deal with it—there is no good solution, only time-wasting workarounds that are not guaranteed to work.
Unstable lens focus with Fujifilm cameras could be an unfixable electromechanical design flaw.
Since Fujifilm has not fixed the issue in at least seven years, and it harkens way back to both Fujfilm and Zeiss Touit lenses on the Fujifilm X series, I am forced to conclude that is the case.
Note also that Play then Delete always resets lens focus, regardless of any setting—not that it should be acceptable with any settings (except perhaps Pre-AF enabled). This idiotic and intensely frustrating behavior has dogged me for every Fujifilm camera I’ve used, wasting my time and causing errors so many times. I’ve had to train myself to never delete an image after doing Play until later.
As for AF-ON working with the camera set to manual focus: that’s the way it ought to work. It's just the smart thing to do. Think of it as an override feature: regardless of settings, pressing the AF-ON button initiates autofocus. This is very useful in manual focus mode.
Fujifilm unstable lens focus has been a bug for years
Six years ago, I published Fujifilm X-E1 Focus Creep Kills Sharpness and Fujifilm X-E1 Behaviors That Kill Images. At that time I called it “focus creep” instead of unstable lens focus. Here is what I wrote in July 2013:
The X-E1 exhibits a FOCUS CREEP: it changes focus even in manual focus mode when nothing is done except to change exposure (aperture and/or shutter speed). The Fujifilm X-Pro1 can be expected to have the same bug
Focus at infinity, make one shot at f/2, make another shot at f/4 and chances are that the focus will creep forward substantially. Depth of field will hide the creep in part. In my field use, I typically shoot an entire aperture series, e.g., f/2, f/2.8, f/4, f/5.6, f/8, f/11 all while leaving focus set to manual: focus ought to remain invariant. Instead it creeps forward.
The problem is not limited to any brand lens (happens with Zeiss Touit and with Fujifilm Fujinon).
With some lenses the focus creeps forward (e.g,. from infinity to as close as 1 meter. I observed this type of behavior with the Touit 32mm f/1.8 in particular. With others it creeps rearward, e.g. from 1 meter towards infinity. I observed this behavior with the Touit 12mm f/2.8 Distagon in particular
A subtle manifestation is a slight change in image position and size between apertures; this proves that the lens has moved (somehow). This change can be as little as 1-2 pixels, or as much as 10-12 pixels.
I had myself forgotten the term I used six years ago. But clearly the problem has existed for the better part of a decade, and clear it is a camera design issue (since both Fujifilm and Zeiss Touit lenses are/were affected)!
Professor Glenn K writes:
This is anecdotal, but I bought my daughter a Fuji X-E3 and 18-55mm lens for her study abroad in Scandinavia. I had tested the lens and it was the sharpest kit zoom I had seen.
When she returned, I noticed that a significant number of shots were very soft. I tested the system and found that it often misfocused, particularly when the focus point was very distant. I have examples of successive shots show varying focus accuracy on a distant target.
I have sent the system back to Fuji with samples and await their feedback. The lens is sharp and the colors are great, but at this point I can't trust the system to deliver a well focused image. That's why I rented a Z6 for my trip to Europe.
DIGLOYD: direct evidence of something not right. but whether it is inaccurate AF followed by untable lens focus or just inaccurate AF is very hard to be sure of. Or even if this particular X-E3 is the issue. But given the long history, I don’t suspect this specific camera. I do know that unstable lens focus can occur in 8 seconds or less , but I don’t know much more than that.
