Fuji INCONSISTENT Autofocus issue Pt. 3

Using an X-T4 with a Fuji 16 1.4 lens in manual mode with BBF I can see the distance indicator jumping about when focusing. When I change the camera setting in Shutter AF to AFS/on and use half press the shutter button to focus, the distance indicator locks on with no jumping about whatsoever.

That is what I see. But the BBF jumping quickly settles to good focus and the AF-S doesn't jump around unless you half press the shutter repeatedly, when you see a random element in where it settles.

I seem to remember reading that lenses focus in small steps and, if these are too widely spaced, errors presumably could creep in (does this apply to Fuji lenses or modern lenses in general?)

I was wondering also if the number of focussing problems was related to the age of the lens, i.e. is there a tighter tolerance built in the new high res lenses for example, or do they suffer the same number and extent of missing the focus as the earlier generations?

Phil

Perhaps, but the jumps are so big that it cannot be the explanation, especially as the BBF which does work properly will have the same number of steps at its disposal.

Once I get a chance, I'm going to experiment shooting with the settings I described. I'll half press the shutter button to acquire focus and then continue pushing the button all the way down. It'll be, press half way and pause then all the way and release.

You'll need to take several frames to see if the distance indicated is consistent like that as much of the time the focus is close enough to make seeing it in images difficult.

I'm wondering if it would prove useful (possibly in a Part 4 posting) if we organized the thread by listing lens AF accuracy ratings such as those mentioned in passing already. Here is my best recollection (no serious testing done):

XF 16/2.8 - good+, XF 23/2 - good, XF 27 (old version) - good+, XC 35/2 - good-, XF 50 - Excellent

XF 18-55 - good-, XC 50-230 - good+, XF 70-300 - poor

Canon EF 100/2 (Fringer adapted) - good-

Now that I'm looking at the list, I can't help but wonder if there is at least some correlation between lens design priorities that cause problems with the focusing confirmation process.

The 70-300 clearly is a lens that puts sharpness above bokeh rendering due to overcorrection of spherical aberrations (resulting in relatively hard edges in the OOF areas). It also happens to be the most prone to misfocusing. Slightly unsharp lenses such as the XF 27 and 50-230 tend to focus better. The XF 50 is sharper, but the OOF areas are also very good (soft) - and it seems to focus the best of all.

It does seem to make sense, but perhaps its just coincidence - or my perceptions are not in line with what others are experiencing. I'm speculating, but that's allowed here!

baobob said:

I disagree, however. Checking carefully trees at infiniy you can clearly see some lack of sharpness when the distance indicator is not at full infinity.

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If these trees are at a large distance (actual infinity is impossible) from the plane of focus they cannot be absolutely sharp.

All WA lenses (and zoom lenses at the WA settings) suffer from this. Starting at 35mm, to things improve a lot, and I have not seen it on the 50f2 and 90f2. The new 18f2.4 shows the issue, and even the 33f1.4 is nog completely immune.

No, the issue seems very similar (only takes place with wider lenses and when focusing at longer distances), and is still quite common especially with the 14mm.

very sharp when the scale is to infinity and a bit blurred when the distance indicator stops a bit before....

OK, now that the smoke has cleared here in the US Northeast I tried recreating this. I focused on a house about 30-40 meters away at 5.6 with the 14. Distance indicator bounced around between 30ft and infinity. I never noticed this before but it appears it affects me as well. This was with the XT30II.

Now try it at 10M at f5.6~f8 and see what happens.

Definitely didn't work for me with either the X-T5 or X-E4. :-|

Just tested. 14 @ 5.6 and 30ft. Bounced all over the place.

This may have been looked at already bit I don't think I saw it anywhere in the threads. The exif data logs where the focus point is on the image. Has anyone looks at the exif data to see if the focus point matches the distance scale, where where the image is in focus, or where it was placed where the image was taken. In other words did it pick the right spot and process it wrong or did it pick the wrong spot. This may help isolate where in the AF process this is happening.

Glad this is being looked into. I have had a focus problem on my x-t20 since I got it in 2017. It was back to Fuji a couple times with no resolution. I almost sold the camera because of this issue. I finally switched to Manual/BBF which significantly improved the issue but I didn't know why it worked. This thread helped answer that question. A side effect of this issue is I only have one AF lens (18-55 zoom) and I primary shoot with legacy lens. I didn't want to spend the money on an AF lens and be disappointed with the results. This could also impact the choice of my next camera if I upgrade. Maybe if Fuji sees this as lost sales they will resolve it.

Never checked, but will when I return from this trip next week.

I have no problem with this issue, never paid attention to it, I don't need to for a darn good reason, I TAKE 3 OR MORE EXPOSURES OF ANY SHOT I feel will be one I will need or want badly. So I can't figure out why you wouldn't do the same?

Even if Fuji came out and said they fixed this I WOULD STILL NEVER TAKE JUST ONE EXPOSURE OF A SHOT THAT WILL BE Important TO ME!!.

If I am just doing walk around shots of every day stuff I always see, then I sometimes take just one exposure, but there are places like the nice waterfall at a state park about 45 minutes drive, I only get there once a year, and maybe only once in 2 years. When I am there I know the shots I will take are more important to me and I want to make sure I get some goid shots, so problem or not, I take sometimes 5 to 7 shots of that waterfall, some with slightly different setting.

So I can't understand how anyone wouldn't do the same. I have never once had to even think anything about this. So there is an obvious way to make this almost non existent in practicality. Are you saying you see a beautiful scene you know will make an awesome photo and you take JUST ONE exposure, WHAT???.

So problem or not, there is an obvious way to make it darn near meaningless. Never take just 1 exposure if any scene you know will be important to you.

There is nothing you could show me about this problem that could make it anything meaningful to my Fuji experience, because I take multiple exposures of any scene I know will make for a goid photo, so the problem simply never enters my world.

So I don't have a fix but I also have no problems with it either.

Wait wait.. are you saying you take MULTIPLE EXPOSURES?!?

AKA Wayne said:

Wait wait.. are you saying you take MULTIPLE EXPOSURES?!?

Click to expand...

Now ya got it!! Perfect way to make this problem meaningless. I bet you do too. If you see an awesome sunset over a gorgeous and well kept farm and field and you pull over and get out to take a shot? No way do you take one shot and go, "OK, got the shot of this amazing scene, guess Ill get back in the car and leave with my one shot". No one does this, NO ONE!!