p.20 #2 · Z8 extremely unreliable/inconsistent AF in mildly low light
I can't read through this whole meandering thread right now…
but can someone tell me if these focus issues occur with F/2 .8 and faster lenses?
(when I was having these focus issues it was with a f/4.0 zoom lens...)
p.20 #3 · Z8 extremely unreliable/inconsistent AF in mildly low light
snapsy wrote:
Received new mannequin today with glass-type eye and eyelashes.
Here is an informal eye AF vs eyelash test on both the Z8 and R3, using each system's respective 50mm f1/.8 lens. This test was under ~7EV conditions. Both cameras had significant trouble locking on the eye of this new darker-skinned mannequin. As for focusing on the eye rather than eyelash, most of the Z8 shots had the eyelash in focus whereas the R3 had the eye in focus.
p.20 #5 · Z8 extremely unreliable/inconsistent AF in mildly low light
ronno wrote:
I can't read through this whole meandering thread right now…
but can someone tell me if these focus issues occur with F/2 .8 and faster lenses?
(when I was having these focus issues it was with a f/4.0 zoom lens...)
Thanks!
Focusing in low light is more reliable with faster lenses, but I don't have a lot of experience on situations where one would use the lens stopped down to a smaller aperture (in low light) and use flash to bring in light; in those circumstances some problems may occur, but I haven't run into them in practice (maybe because this is not a typical scenario for me, but also because the lenses I use are very sharp and contrasty and this helps with the AF). I mostly shoot f/2.8 and f/1.8 Z S-line lenses. When I tried the 24-70/4 and F-mount 70-200/4, it became immediately clear that its AF wouldn't work acceptably in low light situations for my uses. With the lenses that I own, I don't really run into these issues, but most of the time I do shoot wide open when photographing moving subjects that might require eye autofocusing, and when I do shoot stopped down in low light, it is with studio flashes that have their modeling lights (which are continuous lights) and so the problem goes away because the modeling light gives the subject enough light. When I shoot in low available light indoors without using studio flashes, I am almost always wide open, so the AF system gets more light than with an f/4 lens. If I were to e.g. shoot at f/5.6 and mostly bring in the gap in lighting using speedlights, I might very well run into an issue but I don't like the aesthetics of those apertures and the "all-flash" lighting, instead preferring to let in enough ambient light and use a wide aperture.
p.20 #8 · Z8 extremely unreliable/inconsistent AF in mildly low light
SCoombs wrote:
This is an issue I've been fighting with and trying to get a better handle on for a while: in even just slightly lower light, I have found the Z8's subject detection to become extremely unreliable, especially in AF-C.
To be clear, by "slightly lower light" I'm not talking about anything extreme, but something like "there's bright sunlight streaming in through my bay windows and I have someone standing 15 feet away where the sun isn't reaching so I need ISO 2000 at f4 and 1/200" sort of low light.
Also to be clear, by "extremely unreliable" I don't mean that subject detection doesn't work, but that it detects the subject and puts the focus point on the eye and it is green but my in-focus hit rate is <33%.
I've messed around with this a lot and found the following to be true:
1) With any kind of non-subject detect mode the in-focus rate goes up a ton. It's still not perfect in this sort of light, but for instance using single point or one of the dynamic areas in AF-C works far, far more reliably.
2) When going to AF-S, the non-subject detect modes get even better.
3) If I turn on the green AF-assist light in AF-S, it nails things pretty much 100% of the time.
4) I've tried the "adjust settings for ease of viewing" and it sort of improves things, but not much.
5) Starlight mode sort of works in much darker lighting to bring things up to the level of this "sort-of-low light" scenario but still just leaves me with the 33% hit rate instead of not functioning at all.
6) When the subject detect misses in this sort of light (so about 2/3 of the time) it seems to miss by back-focusing a LOT. For instance, it's very, very common if someone is turned at a 45 degree angle that when subject detect is focusing on the front eye and misses, I find the back eye to be very nicely in focus.
Is this really as good as it gets with this system right now? I have seen plenty of people really extol how amazing they find the AF to work in lower light, so I'm hoping there's something I'm missing here. Any help?...Show more →
Why I keep my D850
p.20 #10 · Z8 extremely unreliable/inconsistent AF in mildly low light
SCoombs wrote:
As noted, it does work well with single point mode. Not "precise on every shot," but more like "close enough you can't usually notice it on three out of four shots."
This doesn't mean there's no reason to want to have the "eye-AF" working in situations where the flash is required, or that we can't find it weird that in the very same situation an AF point placed on the eye by the user will work very reliably while the same point place there by the subject detect system will usually not get good focus.
When you say it works well with single point mode do you mean it works with single point AFS or AF-c.
Is it also a problem with single point AF-c
I was about to buy a Z9 in the next couple of days but this is putting me off now.
I can live with using single point in AF-c but it MUST work in lowlight conditions.
I quite often shoot at 1/200 sec F2.8 ISO 3200-6400 using a D850 with 105mm F1.4E at distances of between 6ft-10ft and this seems to closely match the type of scenarios where you encounter the reliability issues with focus being off
If a Z9/Z8 cannot focus reliably at those levels of light with AF-c in single point then it would be useless to me.
p.20 #11 · Z8 extremely unreliable/inconsistent AF in mildly low light
snapsy wrote:
Today I decided to look deeper into the eye AF issues for the 4EV lighting conditions. It occurred to me that perhaps the issue wasn't specific to eye AF or AF-C but simply that the camera's PDAF wasn't sensitive enough for these lighting conditions. To test this theory out I switched to a fixed camera position and added a focus reference to detect if/when the AF was hunting. It's hunting constantly. Then I switched to a higher 6.5EV and confirmed the hunting almost completely disappeared. Then I switched back to 4EV and started experimenting with AF-S and other focus area modes - the camera had significant trouble focusing in AF-S for single point AF over the eye, which to me indicates the root issue here is insufficient PDAF sensitivity at these light levels for this particular subject.
In other words, the eye AF issue I'm showcasing is really a PDAF sensitivity issue. It manifests in eye AF since the size of the PDAF area employed by the subject tracking is a smallish portion of the eye, a portion that AF-S demonstrates focusing trouble with.
Here's the video. The cross-hatch pattern to the left of the mannequin is magnified and split-screen to show when the focus is hunting.
Time jumps:
0:00 AF-C 3.5EV
0:21 switch to 6.5EV, little to no hunting
0:35 switch back to 3.5EV
1:24 switch to AF-S, trouble focusing
2:06 switch to single-point AF
2:25 switch to wide-point AF without subject detection
2:35 switch back to single-point AF
2:52 switch back to eye-AF auto area
p.20 #12 · Z8 extremely unreliable/inconsistent AF in mildly low light
Kipple wrote:
When you say it works well with single point mode do you mean it works with single point AFS or AF-c.
Is it also a problem with single point AF-c
I was about to buy a Z9 in the next couple of days but this is putting me off now.
I can live with using single point in AF-c but it MUST work in lowlight conditions.
I quite often shoot at 1/200 sec F2.8 ISO 3200-6400 using a D850 with 105mm F1.4E at distances of between 6ft-10ft and this seems to closely match the type of scenarios where you encounter the reliability issues with focus being off
If a Z9/Z8 cannot focus reliably at those levels of light with AF-c in single point then it would be useless to me.
p.20 #13 · Z8 extremely unreliable/inconsistent AF in mildly low light
bs kite wrote:
My Z8's AF is no less effective in low light than my D850 is. They both work well in low light.
I agree on my part, when there is too little light to work with on a Z8, there is probably too little light to work with on a D850 as well, and in bright or intermediate light the Z8 is much more accurate.
However, as I've said before I mostly work with fast lenses in low light and don't typically stop them down in such circumstances. Stopping down (e.g. to f/5.6) puts the Z mirrorless cameras at a disadvantage as they fully take advantage of the benefits of larger apertures in terms of benefiting the AF in low light, whereas with a DSLR anything larger than f/2.5 or so can become less accurate overall, f/2.8 is close to the sweet spot for DSLR AF. For the Z cameras, if you shoot at a stopped down aperture, you're also focusing at that aperture (unless it is smaller than f/5.6), which means there is less light to focus based on for those stopped-down photos than wide open. If you shoot an f/2.8 or faster lens wide open, you should get very good AF in low light with the Z8, Zf, or Z9.
p.20 #14 · Z8 extremely unreliable/inconsistent AF in mildly low light
Kipple wrote:
Is it possible VR is contributing to this lack of reliability with focus in lowlight
I think Scoomb determined that the issue he was experiencing was related to flash settings - TTL.
p.20 #15 · Z8 extremely unreliable/inconsistent AF in mildly low light
Has this been improved yet? I am looking to get a z8 and I have a a7r5 which works perfectly with subject recognition. I am wondering how serious this is?
p.20 #17 · Z8 extremely unreliable/inconsistent AF in mildly low light
tester_V wrote:
I'm watching this topic too.. I was really into buying Z8, but it seems the problem is still there and nobody cares bout it...
Because maybe there is not a problem at all ?
Remember. Don't take too seriously anything you read on internet. You don't know who is writing...
BTW...I am not buying new camera. They all sucks.
p.20 #18 · Z8 extremely unreliable/inconsistent AF in mildly low light
The issue is real, and no firmware has been issued since. I sold my Z8 and won’t be buying another one until focus issues have been fixed. (Especially shooting video.)
p.20 #19 · Z8 extremely unreliable/inconsistent AF in mildly low light
Too many users, (wanted to say photographers but they are not) do not even understand what this topic is about. Then why Nikon should worry about it? I'm sure Nikon knew about it from the beginning, they just do not care, users will swallow anything, and that is bad....And the "influencers", the Tube talking heads that ready to say anything for a "click" are completely silent. And the users (not photographers) are still watching and quoting that garbage. Sad time we are living in..
p.20 #20 · Z8 extremely unreliable/inconsistent AF in mildly low light
For what it’s worth, this issue has nothing to do with “extremely” low light for me, I have the same “pizza focus” problem consistently with the ZF in a variety of lighting conditions, though none were extremely bright light, I can try there too.
Seems like a problem with the actual subject detection algorithm, I can pretty consistently reproduce with food/fork/object in front of some lower portion of the face.
