NOTE: This was my post to the earlier thread, which unfortunately was the one that reached the thread limit so nobody was able to reply. Rather than get people to seek it out I've decided to re-post it, so that the affected people can comment and everybody with new issues can see what was said.
To see the comment in context go here: https://www.dpreview.com/forums/thread/4278856?page=8
It is the last post.
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jameszhan wrote:
RubberDials wrote:
jameszhan wrote:
A while ago, ATLshooter had 3 huge threads about eye-AF failure on two copies of A7 III. I thought I should be okay because only 8 people were reporting the same problem in this forum.
I was wrong. My copy (serial number 3379xxx) of A7 III has the exact same issue.
I would caution you against collecting a list of other people's problems and trying to present them as a trend or an indication of something. It's almost impossible to know whether people are having similar problems or whether their issues are occasioned by the same things or are user error or something else all together.
I look at these threads often and I have seen no issues of eye-AF failure that you are referring to, let alone cases from '8 people'
You sure you look at these threads often? You must have missed all the reports.
Please read the following threads if you have the time to. If you make a count, there are now more than 10 people experiencing the same issue.
https://www.dpreview.com/forums/thread/4273349
https://www.dpreview.com/forums/thread/4275541
https://www.dpreview.com/forums/thread/4276377
https://www.dpreview.com/forums/thread/4277220
http://www.fredmiranda.com/forum/topic/1540503
http://www.fredmiranda.com/forum/topic/1543271
I don't expect you to read them, but I'm just showing you this is not just an isolated case and there are more and more people reporting the same problem, some of them are in this very thread we are in.
Right then James, although you didn't expect me to I read all of the threads you linked. Took me a while!
As I expected, and why I hadn't seen it - there weren't 8/10 people with the issue there was one - ATLshooter, and now yourself. Several people with no previous posting history chimed in and said 'yeah, mine does that' but unless people provide detail and test shots you can't presume that they are experiencing the same problem. This is self evident - if someone has a headache because they have a brain tumour it doesn't mean everyone with a headache has a brain tumour. The issue is further complicated by the incessant trolling that takes place on Sony forums.
Of course the fact that some people take the opportunity to bash Sony does not mean that there may be no issue, so let's look at that.
I didn't do any controlled scientific testing; I didn't need to because I used the same lens, 85mm f1.4 GM, on two copies of A7 III (one mine, one in-store on display shelf), and mine was clearly front-focusing while the other was not.
Sony mirrorless cameras do not front or back focus, this is an issue that occurs when the focussing sensor is not exactly on the film plane. Mirrorless cameras can mis-focus and they can focus on things that you didn't want them to focus on but they can't front or back focus.
Well, I'm using the term "front-focusing" quite literally, meaning the focus is achieve at a plane before the intended plane, and that is certainly proven possible with mirrorless cameras, though it's not due to the misalignment of the AF module found in DSLRs.
Here's the A7 III front-focusing, courtesy of ATLshooter: https://youtu.be/ueudeH23ZXg
Here is another thread demonstrating A7 III front-focusing (possible cause is a misalignment between the displayed focus point and the actual PDAF pixel on the sensor in A7 III): https://www.dpreview.com/forums/post/61108811
Okay, that's understood. I think a better term would be mis-focussing because front and back focus is a calibration issue and Sony e-mount cameras are self calibrating.
The discrepancy between the displayed focus point and the actual one has been mentioned before. I have no reason to doubt that this is a real issue.
I'm exchanging my copy tomorrow. I'm making this thread just to raise some awareness because I suspect the problem may be more widespread than we thought.
That's very kind of you but if there was a problem I think it would have been seen by reviewers and some of the more dedicated users on here.
It has been, as shown in the links above. But keep in mind, it doesn't seem to affect all A7 III bodies.
Okay. I don't believe that it has been shown, nor in the examples you gave at the start of the thread.
Apologies in advance for talking about ATLshooter in the third person. It will be confusing if I split my post between him and you. ATLshooter, please jump in at any point.
ATLshooter (hereafter referred to as ATL) created three threads about his AF difficulties and claimed that he had two A7IIIs and they didn't eye AF properly, they 'front-focussed'.
ATL posted several pictures to demonstrate this. The first is here:
https://www.flickr.com/photos/139655841@N03/41408864121/in/shares-gHiJp4/
No one could argue with his claim that eye AF has not worked. Neither eye is in acceptable focus.
ATL then links two more pictures. Only one is with eyeAF, the second one. Of it he says:
"shows what eye af does almost 100% of the time. If you download the image and zoom up you will see that only the bridge of the nose is in focus. The eye lashes are definitely out of focus, and the eye brows are even slightly out of focus. Only the bridge of the nose is dead in focus."
Here is the picture:
https://i.lensdump.com/i/8BO4nF.jpg
In fact the eyelashes on the model’s right eye are in focus and this is what the camera has focussed on. The eyelashes on the right eye are NOT out of focus.
He then posts four more pictures.
Two are close up and two head and upper body.
#2 and #4 are with Eye AF
The first shot with eye AF is not that sharp. but Depth of field is much thiner at close distances. ATL doesn’t seem to appreciate this.
The second shot with eye AF (The 4th overall) is pretty sharp although ATL says:
"Fourth shot: Further away using eye AF. Still missed, focused on the bridge of the nose. It's harder to see but the eyes are definitely out of focus."
Here are links to the two photos.
First eye AF photo (2nd overall) https://www.dpreview.com/forums/post/61020370?image=1
Second eye AF photo (4th overall) https://www.dpreview.com/forums/post/61020370?image=3
This is not the sharpest possible, but the eyes are definitely NOT out of focus as ATL claims.
That’s it. Despite filling three threads to capacity complaining about the eye AF, ATLshooter has only actually posted FOUR pictures taken with eye AF. Of those four, one was taken in extreme close up, where the eyeAF has failed. The second was also close up and is poor. Of the other two, BOTH are acceptable, though one is sharper than the other. Neither is as sharp as the spot focus with contrast phase. This is not unexpected behaviour. Without the final contrast detect phase (where the lens cycles in and out) which doesn't happen in eye AF AF-C, the camera is only using phase detect. It is simply not as precise at large apertures where depth of field is very shallow as the full hybrid focussing cycle.
I noted the following about the ALT’s testing. He did not use a tripod. He did not use the same position or composition for any shot. It was pointed out to him that the focus was on the plane of model’s eyelash on more than one occasion, but he continually referred to the focus ‘jumping onto the bridge of the nose’ which cannot have happened. ATL was deriving his eye AF expectations from using the system on aps-c and at smaller apertures.
ALT ignored three posts by Horshack, who is one of the most knowledgeable members of the community who suggested a simple test for confirming the mis-focus was a phase detect issue.
ALT used the fact that he got the results he wanted with the A7rIII (a completely different camera model) to ‘prove’ that both his A7III’s were faulty. This is a logical fallacy.
The following two threads by ALT demonstrate a certain unfamiliarity with the system and perhaps FF photography (He apparently did not know what lateral chromatic aberration was).
https://www.dpreview.com/forums/thread/4280294#forum-post-61109691
https://www.dpreview.com/forums/thread/4277930
Please go test out your A7 III's eye-AF with a fast lens before the exchange/return period expires.
No need to debate whether it's user error or not as it is already been argued to death in ATLshooter's threads. And in my opinion, it is quite clear cut that this is not user error.'
Lol. Sadly when it comes to issues to do with focussing or lens sharpness it usually is user error. Never wise to dismiss it.
Sure.
Note that this two shots are not the only ones I took. I was using my 24-70 GM at f2.8 and I already noticed a bit of softness at the eye with eye-AF, which was why I went into the store today and tested it with a f1.4 lens.
I would like to thank ATLshooter for raising awareness of it. I don't think I would go in store to get a f1.4 lens to test if I didn't know this problem could exist in some copies of the camera. I currently don't have the budget to buy another lens, and if I found out about the problem when I saved up enough to buy a fast prime, it would most likely be too late for me to exchange.
It doesn't look to me as if there is anything wrong with your camera. In the first photo the focus is on the left eye (the left eye of the model) so I'm not sure why you have reproduced a detail of the right eye. The face is at an angle and the depth of focus at maximum aperture is very small.
Eye-AF box picked up the right eye and confirmed focus on it; instead in the final image, the focus is on the left eye, proving a back-focusing issue. I had her face at an angle on purpose so it's very easy to see if the focus is front-focused or back-focused. That's how you check front and back focusing, traditionally with a ruler at a 45 degree angle.
If I said to you I'm going to pick up the green ball but instead I picked up the red ball, which ball would you say I picked up? The fact that the focus is on the left eye suggests the camera focussed on the left eye, rather than the camera focussed on the right eye and somehow mis-focussed.