Attention all FUJI GFX users- AF shift issues when shutting down

[GeneHack]

Hi fellow GFX users,

first of all please excuse my spelling and grammar errors, since I’m not a native English speaker-

We recently found out the hard way that the GFX line seems to exhibit a very strange behavior.
Producing at very hot temperatures (Arizona!) our GFX100S was constantly on the edge of overheating, throwing blind pixels and sometimes shutting down. We later discovered that we had a lot of out soft, of focus images thus the camera was set to manual. Camera was on a heavy tripod further secured with massive sandbags.
The lenses we used were the Fuji 23mm prime, Sigmas 12-24mm zoom via adapter and Canons EF 24-70mm II f2.8.
Placing a fan directly under the LCD display (slightly protruded from the body), plus and open battery tray door mitigated the situation slightly.

We witnessed the following behavior which is IMHO unacceptable for a professional camera:

When shutting down the camera, no matter forced or via the switch, the camera moves the lens focus to a resting position. At least tries. Some lenses like the Sigma zoom just slightly move focus, the Fuji own and the Canon (via adapter) get moved to infinity position.
Switching on the camera, the focus moves back to the last position, however layering the files afterwards always shows a pixel movement making it impossible for the postproduction team to just layer the exposures before and after the restart.
now comes the strangest part: the Sigma Primes via adapter we have (24+50mm), do not show this behavior they stay rock solid like a manual setting should.

We could verify the same behavior with a colleagues GFX, and the new GFX II

No other camera shows this behaviour. Manual means a fully controllable, non moving focus.
Maybe you can test it yourself with and without 3rd party AF lenses.
What motivation drove Fuji engineering to this decision and do you think this can be prevented by a software fix? And what is the best and most effective way to contact the responsible entities here?

 

[dbateman]

See if Pre-AF is set to on in the menu. If so change it to off.

That might change this behavior.

 

[Rodenmg]

Most likely this is due to the Fuji lens using linear focusing motors. When powered down the GF23 focusing group is free to float around inside the lens. Tilt the lens back and forth and you’ll feel it moving. Some like the Gf100-200 “park” the focusing group when powered down so there’s no movement.
Why the camera can’t remember where the focus was when powered off I don’t know.

--
... Mike, formerly known as Rod.
... https://www.flickr.com/photos/198581502@N02/

 

[left eye]

Don’t all focus by wire lenses do this? - as the focus isn’t mechanically linked to the focus ring. Lenses with true mechanical focus as designed for dSLRs offer 100% repeatable focus position even after a camera off / on.



There’s many reasons to like the GFX and EVF’s, but focus by wire lenses have almost totally turned me away from mirrorless cameras now. I often have true manual focus lenses on my GFX now, due to this exact reason, or I just use my Pentax 645Z - an all round more pro camera IMO.

 

[Rand 47]

If I remember correctly, Jim has reported (can’t remember which body specifically) that there can be a shift in focus from shot to shot, in manual focus mode, even when the camera remains “on.” As I recall, it wasn’t much, but it wasn’t nothing.

Rand

 

[JimKasson]

If I remember correctly, Jim has reported (can’t remember which body specifically) that there can be a shift in focus from shot to shot, in manual focus mode, even when the camera remains “on.” As I recall, it wasn’t much, but it wasn’t nothing.

Rand

Good memory, Rand!

 

[SrMi]

If I remember correctly, Jim has reported (can’t remember which body specifically) that there can be a shift in focus from shot to shot, in manual focus mode, even when the camera remains “on.” As I recall, it wasn’t much, but it wasn’t nothing.

Rand

Good memory, Rand!

Did you observe it on your X2D as well?

--
https://blog.kasson.com

 

[GeneHack]

PRE AF was off. That’s the first thing we double checked.

 

[GeneHack]

If I remember correctly, Jim has reported (can’t remember which body specifically) that there can be a shift in focus from shot to shot, in manual focus mode, even when the camera remains “on.” As I recall, it wasn’t much, but it wasn’t nothing.

Rand

That makes replicable professional still life use impossible.

 

[GeneHack]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

 

[left eye]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

...are those Sigma's in a dSLR mount? i.e. true mechanical manual focus, not focus by wire.

 

[GeneHack]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

...are those Sigma's in a dSLR mount? i.e. true mechanical manual focus, not focus by wire.

Those are „Art“ lenses with USM AF in Canon EF mount.

with that same EF mount the Canon 24-70mm exhibits the behavior of the Fuji own lenses. The camera seems to emit one last „bit“ which leads the lens to move to Infinity

 

[Rand 47]

If I remember correctly, Jim has reported (can’t remember which body specifically) that there can be a shift in focus from shot to shot, in manual focus mode, even when the camera remains “on.” As I recall, it wasn’t much, but it wasn’t nothing.

Rand

That makes replicable professional still life use impossible.

Not necessarily. I use back button focus in manual focus mode. And if I have any doubt, I’ll use the button to re-focus (without having moved my focus target box) before each frame. As a practical matter, I’ve not found focus drift to be an issue.

Alternatively, one could use a 3rd party manual focus lens (one with a real mechanical focus mechanism), or either of the GF T/S lenses that are manual focus only, “mechanically.” The 110 in particular is a GREAT still life lens.

Rand

 

[GeneHack]

Refocusing, even if precise leads to pixel differences between exposures as explained above. That doesn’t work in a replicable surrounding. No other camera does that.

i have a canon TS-E 17mm coming next week but i have my doubts

 

[left eye]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

...are those Sigma's in a dSLR mount? i.e. true mechanical manual focus, not focus by wire.

Those are „Art“ lenses with USM AF in Canon EF mount.

Ok so they are true manual focus, i.e. when the camera is off, you can adjust the focus with the focus ring. With focus by wire, and the camera off, the focus ring will turn but do nothing - it only 'does something' when the focus motor is on, hence the focus jumps turning the motor on and off (with the camera on and off).

Focus by wire is quite troublesome with all mirror-less cameras, it's a bit more accurate, less internal slop, due to eliminating the mechanical coupling to the focus ring, but for many pro's true manual focus lenses are better - and they are native only to dSLR cameras (not mirrorless). You can adapt true manual focus glass, i.e. Pentax 645 lenses to the GFX, but then you may as well have a 645Z for which you can then also use those same lenses with AF.

With your EF mount glass, if you want to manual focus and have shot to shot repeatable static focus, use a dumb adaptor, not one which transmits auto-focus.

 

[GeneHack]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

...are those Sigma's in a dSLR mount? i.e. true mechanical manual focus, not focus by wire.

Those are „Art“ lenses with USM AF in Canon EF mount.

Ok so they are true manual focus, i.e. when the camera is off, you can adjust the focus with the focus ring. With focus by wire, and the camera off, the focus ring will turn but do nothing - it only 'does something' when the focus motor is on, hence the focus jumps turning the motor on and off (with the camera on and off).

Focus by wire is quite troublesome with all mirror-less cameras, it's a bit more accurate, less internal slop, due to eliminating the mechanical coupling to the focus ring, but for many pro's true manual focus lenses are better - and they are native only to dSLR cameras (not mirrorless). You can adapt true manual focus glass, i.e. Pentax 645 lenses to the GFX, but then you may as well have a 645Z for which you can then also use those same lenses with AF.

With your EF mount glass, if you want to manual focus and have shot to shot repeatable static focus, use a dumb adaptor, not one which transmits auto-focus.

exactly -thanks for your explanation, but why does the Sihma 12-24mm exhibit a sort of hybrid behavior? It is manual focusable yet when switching the GFX the focus moves yet not to infinity?

and yes I will use a dumb adapter or tape the connectors, but wouldn’t it be easy for Fuji to implement a software toggle?

 

[Rodenmg]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

...are those Sigma's in a dSLR mount? i.e. true mechanical manual focus, not focus by wire.

Those are „Art“ lenses with USM AF in Canon EF mount.

Ok so they are true manual focus, i.e. when the camera is off, you can adjust the focus with the focus ring. With focus by wire, and the camera off, the focus ring will turn but do nothing - it only 'does something' when the focus motor is on, hence the focus jumps turning the motor on and off (with the camera on and off).

Focus by wire is quite troublesome with all mirror-less cameras, it's a bit more accurate, less internal slop, due to eliminating the mechanical coupling to the focus ring, but for many pro's true manual focus lenses are better - and they are native only to dSLR cameras (not mirrorless). You can adapt true manual focus glass, i.e. Pentax 645 lenses to the GFX, but then you may as well have a 645Z for which you can then also use those same lenses with AF.

With your EF mount glass, if you want to manual focus and have shot to shot repeatable static focus, use a dumb adaptor, not one which transmits auto-focus.

exactly -thanks for your explanation, but why does the Sihma 12-24mm exhibit a sort of hybrid behavior? It is manual focusable yet when switching the GFX the focus moves yet not to infinity?

and yes I will use a dumb adapter or tape the connectors, but wouldn’t it be easy for Fuji to implement a software toggle?

Is it possible the camera's IBIS is turned on? I know silly question but....

 

[left eye]

Why some Sigma primes don’t exhibit this behavior? Non linear motors then?

...are those Sigma's in a dSLR mount? i.e. true mechanical manual focus, not focus by wire.

Those are „Art“ lenses with USM AF in Canon EF mount.

Ok so they are true manual focus, i.e. when the camera is off, you can adjust the focus with the focus ring. With focus by wire, and the camera off, the focus ring will turn but do nothing - it only 'does something' when the focus motor is on, hence the focus jumps turning the motor on and off (with the camera on and off).

Focus by wire is quite troublesome with all mirror-less cameras, it's a bit more accurate, less internal slop, due to eliminating the mechanical coupling to the focus ring, but for many pro's true manual focus lenses are better - and they are native only to dSLR cameras (not mirrorless). You can adapt true manual focus glass, i.e. Pentax 645 lenses to the GFX, but then you may as well have a 645Z for which you can then also use those same lenses with AF.

With your EF mount glass, if you want to manual focus and have shot to shot repeatable static focus, use a dumb adaptor, not one which transmits auto-focus.

exactly -thanks for your explanation, but why does the Sihma 12-24mm exhibit a sort of hybrid behavior?

the MF / AF switch on the lenses is still an electronic switch, so even if in the MF position, if the the GFX doesn't see this (due to lag in the adaptor waking up, even for a split second), the GFX will assume the lens is in AF mode.

AF adapters I've found are fraught with minor issues, in the end I couldn't deal with the hassle. Now I use native GFX lenses, or adapted manual focus lenses with dumb adapters, keep it simple and solid.

It is manual focusable yet when switching the GFX the focus moves yet not to infinity?

and yes I will use a dumb adapter or tape the connectors, but wouldn’t it be easy for Fuji to implement a software toggle?

I recommend Kipon as the 'dumb' adaptor, not that it offers anything more than say a K&F concept, except for evidently better and simpler build quality (and usually Kipon's are lighter weight).

In my book there is still a place for high-res dSLRs ...not only for the true manual focus AF lenses, but also the OVF - which you don't need to 'turn on' to focus a shot, but that's another subject!

 

[GeneHack]

IBIS of course off.

And as we know the „infinity park position sydrome“ is independent from an adapter in place or not.

 

[JimKasson]

If I remember correctly, Jim has reported (can’t remember which body specifically) that there can be a shift in focus from shot to shot, in manual focus mode, even when the camera remains “on.” As I recall, it wasn’t much, but it wasn’t nothing.

Rand

Good memory, Rand!

Did you observe it on your X2D as well?

Never observed it by accident. Never specifically tested for it. In general, I don't trust FBW lenses to remain focused over long time periods.