p.6 #1 · Z8 extremely unreliable/inconsistent AF in mildly low light
armd wrote:
AA has become a much better option for birders for BIF and other specific circumstances though it's not a be all, end all. One should be familiar with Wide-large, Wide-small, and custom AF, their applications, and other settings.. If you are new to birding with your Z9/Z9, I suggest buying Steve Perry's book, https://bcgwebstore.com/product/the-ultimate-nikon-z9-setup-shooting-guide-for-wildlife-photography/.
With the refinement of the AF firmware there is lesser need for 3D AF and in fact there are some downsides with using it, especially, if the system loses subject capture for any reason.
Thank. I have Steve Perry’s book and also programmed the focus modes that you mentioned above. It’s nice to be able to have various AF modes that are customizable.
p.6 #6 · Z8 extremely unreliable/inconsistent AF in mildly low light
sjms wrote:
can you use a tape measure from the sensor plane to the focus point and then the lens chart for DOF?
Sure. Focus distance is 38 inches, producing a DoF of 1.67 inches at a CoC of 0.030mm. The mannequin's eye measures 1.25 inches from corner to corner.
Can you return the favor and tell me how we can apply that information to establish whether the Z8/Z9 AF's system is performing to specification in this experiment?
p.6 #7 · Z8 extremely unreliable/inconsistent AF in mildly low light
i'm not. its a of whether there is a level of consistency/repeatability. is there? with a DOF of 1.67 in, not much. oh, there's more going on there too.
p.6 #8 · Z8 extremely unreliable/inconsistent AF in mildly low light
armd wrote:
Again, did you turn focus assist illuminator on/off? It's something I do for my wildlife settings bank, but then I have it on in my portraiture set-up. The working distance is fairly limited, around 3-10' (see: https://onlinemanual.nikonimglib.com/notice/af-assist_illumination/en/z8/)
I mentioned in my original post that when using the illuminator the focus is nearly 100%, but the illuminator is only functional in AF-S, making it unusable for event photography where a significant amount of the work requires AF-C.
p.6 #9 · Z8 extremely unreliable/inconsistent AF in mildly low light
sjms wrote:
i'm not. its a of whether there is a level of consistency/repeatability. is there? with a DOF of 1.67 in, not much. oh, there's more going on there too.
Not sure yet on the consistency across tests. I've only done one test and in that test, the higher EV scenario consistently focused on the left eye whereas the lower EV scenario did not, even though in both scenarios the camera indicated it was tracking the left eye.
p.6 #11 · Z8 extremely unreliable/inconsistent AF in mildly low light
sjms wrote:
i think you are going to find out a few things. the lighting method. you can ignore that if you wish but i wouldn't.
At this point there are an innumerable number of factors that have to be checked. Lighting is near the top of the list, independent of its EV, including its directionality and temperature.
p.6 #12 · Z8 extremely unreliable/inconsistent AF in mildly low light
right out of the gate that flash is not designed to work with the Z cameras. my old Nissin MG8000 did not sync well my Z6 or Z9 no matter what it displayed on the screen. worked really well on my D500 and D850 when used.
p.6 #13 · Z8 extremely unreliable/inconsistent AF in mildly low light
sjms wrote:
right out of the gate that flash is not designed to work with the Z cameras. my old Nissin MG8000 did not sync well my Z6 or Z9 no matter what it displayed on the screen. worked really well on my D500 and D850 when used.
Again, unless one is using the flash's AF assit light, the flash has nothing whatsoever to do with the camera focusing. The camera focuses without the flash doing anything and then the flash fires when the shutter is released. If the flash isn't synced well with the camera, you will get black bars, or banding, or other significant effects. It does not affect the focus, which has already been set before and without the flash doing anything.
p.6 #15 · Z8 extremely unreliable/inconsistent AF in mildly low light
An update:
Today I installed the 2.01 firmware and when I sat down to get a few samples of this problem I noticed that the focus was behaving more consistently. I took around 100 shots, about 80% with flash, mixing subject detect and single point. My initial impression reviewing on camera was that it was behaving much better than it had been. It looked like almost everything was a focus hit.
When I put them into NX Studio for review I found the truth is a bit more mixed than that. On the one hand, I would say that it did behave better. On the other hand, it was still off about half the time or more.
The big difference, and the reason I thought when reviewing on camera that it was much better, is that a much smaller number of the shots are such significant misses that it winds up with the entire person out of focus. Most are misses where careful examination will reveal that the wrong eye is in focus but there's really just a slight difference between the two eyes so that when viewed at a more normal size it might be missed. Some are misses when the wrong eye is in tack sharp focus, and in these cases the other eye is totally out of focus. A handful missed badly so that the ear is in focus or something else altogether in front of or behind the person.
Of course, this probably means that critical focus is still being missed. This is because when the focus is where it should be, the depth of field is such that the in focus eye is sharp while the other eye is totally out of focus. When the focus misses more significantly, the wrong eye is in sharp focus and the eye that had the AF point on it is totally out of focus. Therefore, when both eyes look okay with one slightly better, it probably means that the focus has actually missed somewhere in the middle.
This also agrees with some of snapsy's findings. One, it wasn't really missing (at least not tonight; it did before) when the person was square to the camera. Two, when it did miss it most of the time missed by focusing on the wrong eye.
Now this was just one quick test and I may try it again and find it working again like it did before. However, if the results of this test are accurate - and they do agree with snapsy's results so far - then it would seem to indicate that what is causing the out of focus effect may be that the system is somehow "behind scenes" just plain focusing on the other eye. This would also perhaps explain why the system seems to perform better with single point (though I didn't get much success with that at my event last night): because the actual focusing is working correctly, but the subject detection is for some reason sometimes telling the system to focus on a different eye from the one it reports.
p.6 #16 · Z8 extremely unreliable/inconsistent AF in mildly low light
sjms wrote:
honestly no.
i strongly suggest you try a flash that is made to be used with it. go borrow a SB700
I'd be happy to listen to you if you can explain any rationale at all as to why the flash, which has no interfacing with the focus system at all, would cause the camera to miss focus.
You could also explain how the flash, when sitting on my shelf and unattached to the camera, is still somehow managing to cause it to miss focus in low light.
Also, I have to add that the SB700 was not made to be used with the Z system as it was released long before the Z system existed.
I have read this and I had read this long before you linked it. It doesn't in any way support the contention that the flash can affect autofocus performance.
It doesn't even support the claim that using the wrong flash may sync badly. It suggests that some flashes may simply fail to work if a firmware update changes something, but it doesn't say anything about a flash appearing to work but actually having the sync timing off.
Perhaps worst of all, the only flash that this article specifically says is unsupported by Z cameras - the SB700 - is the one you specifically recommended when arguing that my flash is unsupported!
The only things Hogan says about flashes failing to work are:
1) Some Nikon flashes may not be controllable via the in camera menu.
2) There may be problems with radio communications between older flashes when used on the Z-system.
3) Using an older flash may cause the EVF to display an exposure that is too dark.
The only one of these that might have anything to do with the focus is #3, but since we're setting the camera to adjust the EVF for ease of viewing this does not come into play.
And again, this problem happens when there is no flash attached at all. You strike me as someone who is repeating the same posts over and over without actually reading the replies offered to them.
p.6 #19 · Z8 extremely unreliable/inconsistent AF in mildly low light
you are correct i did not read it with comprehension. not one of my better nights. so again, i apologize for my major DUH!
to everyone on this thread i do profoundly apologize for ignorance and lack of focus on this subject. it has been a very long time since i have had a need for flash.
If you go further with this and if you have time amongst the other scenarios you will be testing, I would be very interested to know if the problem persists if you change to 3d AF mode without subject detection to lock on to the subject's nearest eye.
