I'm thrilled that you implemented it straight away! Thank you! I've had the Z8 for a month and have been following this topic with interest. I have no problems with it. I do think that the autofocus could be more reliable and precise on the iris, but in the real world it is more than precise and none of my customers would complain that the focus is not 100% exact. Even the Z6 and Z7ii were enough for that. But I'm interested in technology and think it's good and interesting that tests are being carried out here!
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Z8 Subject Detection Inaccurate in Low (but not that low) light
- Thread starter SCoombs
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Andre Yew
Veteran Member
You said Nikon cameras had trouble focusing in studio situations like a generality, but in fact the point of the whole thread is that it's subject detect that seems to mess up focusing. Jim also shared some Z8 settings which he says helps him get high hit rates in dark ambient lighting for his daily work, so I'm not sure what you're objecting to.
HyperCypher
Veteran Member
When I bought my Z6ii I noticed that AF C almost never "settled" in the same way that my D750 would ... what I noticed is that even the very slightest camera movement cause AF C to "get active" and that activity looked like a contrast detect "check" which by nature is a "defocus/focus" routine ... not a phase focus "shift" which is what I was used to with DSLRs ... Nikon mirrorless AF is a combination of phase and contrast detection I believe. DSLR AF is (through the OVF) strictly phase based.
I have a Z8 now and although it is better, it still exhibits the same Nikon mirrorless DNA.
I'd be curious to see how your test would go with the camera on tripod to eliminate any camera body movement, and thus (to my mind) extraneous AF C contrast detect hyper activity.
I have a Z8 now and although it is better, it still exhibits the same Nikon mirrorless DNA.
I'd be curious to see how your test would go with the camera on tripod to eliminate any camera body movement, and thus (to my mind) extraneous AF C contrast detect hyper activity.
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I agree this may be an interesting experiment, BUT at the same time it would be of very little practical use to a scenario that seems to be impacting those who it is impacting in cases where a tripod is not possible.
HyperCypher
Veteran Member
yes but it would tell us something (that I suspect) which is that in lowering light Nikon mirrorless AF relies increasingly on contrast detect which uses defocus ... and my untested conclusion having owned a Z50, Z6ii, and Z8 is that contrast detect checking is triggered excessively by camera movement too small to actually throw focus off enough to warrant the defocus/focus cycle required by the contrast detect "check" ...
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Dinosaur dave
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Over complicated and excessively clumsy AF settings!
..... the system needs revising so you don't have to be AF menu memory magician to just take a successful portrait time after time with the nearest eye tack sharp and not tack sharp eyelashes ...
how good would be an AF menu setting: "single subject eye detect" which just works?
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Very interesting, thanks for all the work.
From these videos it does look a lot like they're comparable in the regime where they both indicate the eye. But can you explain what you mean? "Beyond the actual capability", what capability? If you used single point AF and placed the point on the eye indicated by the subject detection mechanism, presumably it'd focus just fine--are you saying that this isn't true? If not then what capability do you think is being exceeded?
Did you also try with better light? like.. iso 400-1600 ? I think this can and often also does happen with better light, and in my experience it happens much less with my 70-200Z compared to the 50mmZ and 24-120Z
jimdelves
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When I got married 14 years ago, we got back an album of quite beautiful photographs especially of my wife and her now deceased parents and of the wonderful ceremony. Recently, I looked at them again with a pixel peepers eye. About 1/3 are missing critical on-the-eye focus.
Did we give a damn, or even notice? Not at all, the album is a brilliant record of the day. Composition, colour, and record all are more important than focus to the customer. Advertising, editorial may be different, but weddings? No
Rodenmg
Veteran Member
You keep saying that you read somewhere... In my actual experience I don't see this issue. Not saying others don't and Not bragging or saying the Z9 is better than the Z8. I consider the two essentially the same camera. At f4 I do get some oof shots. but not at f1.2.
I don't have a model handy, or a creepy head handy so I just used my creepy self. I know, creepier that Horshak's head but it is what it is. This is me using a remote release so I can't even see what the focus is doing from viewfinder. Just half press for 1 second and release. I used a flash like the original post but with the flash off the exposure at f4 would be 1/60 @ iso4000. Quite dark. But I shot at f1.2 with the flash.
Full frame facing forward for reference.
Consecutive shots turning head . 200% magnification.
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... Mike, formerly known as Rod.
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After having started to take photography more seriously I went back and looked over my wedding photos to see what I could pick up and I was shocked by how many were out of focus or blurred., so I partially agree.
Still, I think in 2024 the wedding market is a bit different and more saturated and the overall image quality can be a differentiator.
I'm saying that for the very oblique angles or when very close to the subject the camera is indicating it's selecting and focusing on the right eye when it's not, so perhaps the camera can't support eye AF correctly in those situations but the display is giving an indication that it can.
Rodenmg
Veteran Member
Sounds very logical.
Right, so what I was asking is whether you suspect some particular reason for the eye AF to not work in those situations.
It looks like the eye is correctly detected, ad if so it would be the AF system that fails; so, do other modes (eg single-point C-AF) also fail sometimes if you put the AF point on the eye manually from this angle, or not?
I'd check but don't have a mannequin.
It focuses correctly if I manually set the AF point to the eye. If I had to guess I'd say the bug is the PDAF system thinking it's acquired the eye when it hasn't, or the system using the wrong PDAF pixels.
In the video you put on youtube at 70mm it moved the eyebox from right to left eye, and clearly didnt do ANY adjustment to focus, and yet it claimed to have it.
I strongly suspect that the eye detection just does not actually attempt to focus where the box is.
But atleast we can hopefully now put to rest the whole "user error" and "trolls" explanations that are so often given for these things
This observation is really at the crux of this problem.
I have many Z6 & Z6ii images with this affliction.
Having been told "user error" and "read the manual" almost six years ago when I first raised this exact issue with the Z6 (and then the Z6ii), I would hope you're right.
j_photo
Veteran Member
I've been saying off and on for some time that detecting the eye and achieving focus are separate things. The camera is recognizing the eye. But it's not succeeding with focus. It's not unlike when we manual focus: First we must detect the subject then we must adjust focus. It seems the camera's detection abilities exceeds it's focus abilities.
OR that the subject detection system is throwing off the focus system which apparently focuses quite accurately when subject detection is not active. It's the interaction of the two subsystems that seems to be primary here.
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