Struggling with Z8 focus tracking

[beano]

I'm not sure how many people actually subject their systems to test it? When I look at the image at normal magnification, it appears in focus. Now pixel peep at 100% and it's all too apparent that the observable focus point was different than the one indicated by the EVF green square and the one recorded in exif.

Quite candidly, I am still trying to better understand Nikon's AF system and Thom Hogan admits that his questions to Nikon yet to be answered. I do recall an older article that he published on his website which indicated that Nikon (Sony) sensors use the blue pixels in the arrays for AF, see: https://www.sansmirror.com/articles/choosing-a-mirrorless-camer/autofocus-sensors.html. Getting back to the portrait issue, if I recall correctly your subjects had blue eyes as does my spouse. I haven't dived into this further to determine whether the OOF issues occur with other eye colors? This would be interesting and might explain why I can't duplicate this phenomenon on my cat (or dog) or why others may not be encountering the same issue. Unfortunately, it doesn't address the (unrelated?) problems you're encountering in sports.

This is one of the main reasons why I am hoping that Z8/Z9 will get the MF eye detect feature like the Zf has, as I am getting better results with my Voigtländer 50 f/1.0 running full MF on my Zf wrt focus-accuracy, compared with my Z8 and 50 f/1.2 S in AF with subject detection/people.

At least with human subjects, even with the fastest Portrait lenses, I do find the Z8 frequently misses human eyes, even if SD /people is selected. It‘s not consistent across the 50 1.2 /85 1.2 /135 1.8, but enough to notice. The Z9 fares better, imho.

I guess we’re all waiting for the new FW updates, as rumours have it that there will be significant changes to the AF system, but, caveat, it’s still rumours only at this stage.

 

[tomcat]

Okay, but let's be very clear about what we're talking about here: the camera has already focused on the keeper and done so without any hesitation or trouble. I put it on him and press AF-On, and immediately it focuses. It is only when the subject moves that the part of the AF system which is supposed to stay focused on something until a relatively long delay has passed is apparently not doing that and is allowing the system to refocus right away.

Put differently, I can acquire focus on a subject like this almost 100 times out of 100 and the better contrast of the background doesn't confuse it. The AF point is on the subject and it focuses on it like a champ. When the focus point moves off of the subject, even for 1/20 of a second, it lets go in spite of the mode/settings being such that it is supposed to hang on. THAT is the problem.

This happens to me sometimes too--not hanging onto the subject--so I set my AF lock-on setting to 5 so that the camera will refocus almost instantly again. It seems to me that I remember Steve mentioning this phenomenon in a video 1-2 years ago and mirrorless dynamic area AF doesn't work as well as the DSLR---but don't quote me on this because he'll be reading this thread soon enough

I find that when I am tracking a baserunner going from 1st to 2nd, the AF will stay locked on the runner's head, even when he gets beside or behind the 2nd baseman----however, I have to have an amazing skill level and steady hand to keep the target on the runner's helmet, because if my hands stray for a moment and that focus box strays to one of the other accessory points within the array, that 1/20 sec you mention, then I'll lose the focus for a very brief period ( but AF lock-on of 5 gets me back on focus after 2 frames)

 

[SCoombs]

You hit the nail on the head with this comment: Your quote: " if I get a subject very large in the frame, there is a difference. If I get something that fills the entire height of the frame, for instance, I can put the main AF point on them and then move so that they're now under a helper point and with A3 set to 1 (quick) it will refocus almost immediately whereas with A3 set to 5 (delayed) there is a very nice, healthy delay before it refocuses. In fact when doing this there is even a nice little indication: the AF point turns briefly from green to red right before it refocuses".......you must remember that the camera does NOT know what the subject is and unless you fill the frame with as large of a subject as you can, then the AF sensor may think some other object in the frame is the subject. I have shot thousands of sports images with my Z6 and Z6ii and I use dynamic area AF exclusively. So long as I can keep the center focus box on my target, my keeper rate is >90%. But as I am getting older now, in the past 6-8 months, it is more difficult to track a moving subject when they are jumping around. Any and all of the oof images are 100% MY fault because I can see where my focus target box ended up on the background. This is strictly my fault for not following the subject continuously, even when not actually capturing the shots.

So long as you keep practicing with dynamic area AF with longer focal lengths to fill the focus box, you'll nail this technique down like I did--seriously. I would have no trouble whatsoever tracking either of those 2 guys above no matter where they went

I am definitely supportive or accepting or buying into the idea that the better one can manually track, the better things will be. However at the same time, there is a reason that modes like dynamic area exist because even for very seasoned photographers sometimes a little margin of error is needed. In sports, a player may very suddenly and move very quickly and it may take a fraction of a second to adjust to it, or another player may run in between the camera and the target so that no matter how good the photographer is the camera needs to do its part to keep focus on the briefly occluded target. For wildlife, these same sorts of things also happen.

In sports, I would say that I can track players keeping the central point on them for 95 frames out of a hundred, often maybe even 99. The problem is that right now none of the AF modes are able to hang onto the subject for that one frame and so the camera grabs the background and when that happens it is very difficult to get it to come off of the background. It's doable if you know how, but in a fast-paced environment like sports or wildlife it's more than enough time to lose the action that you actually wanted a photograph of.

 

[SCoombs]

This is one of the main reasons why I am hoping that Z8/Z9 will get the MF eye detect feature like the Zf has, as I am getting better results with my Voigtländer 50 f/1.0 running full MF on my Zf wrt focus-accuracy, compared with my Z8 and 50 f/1.2 S in AF with subject detection/people.

At least with human subjects, even with the fastest Portrait lenses, I do find the Z8 frequently misses human eyes, even if SD /people is selected. It‘s not consistent across the 50 1.2 /85 1.2 /135 1.8, but enough to notice. The Z9 fares better, imho.

I guess we’re all waiting for the new FW updates, as rumours have it that there will be significant changes to the AF system, but, caveat, it’s still rumours only at this stage.

I have seen a few people mention rumors of this significant AF update, but I haven't seen these rumors on Nikon rumors or anywhere else, really. Where are the rumors from?

 

[beano]

I have seen a few people mention rumors of this significant AF update, but I haven't seen these rumors on Nikon rumors or anywhere else, really. Where are the rumors from?

Hi SC, I need to check again, I can swear I saw some of the Nikon Youtoobers refer to the AF updates. Let me see if I can find it, those guys are generally in the know to some degree, a few are most likely undercover Ambassadors, I suspect.

 

[Len Shepherd]

As I mentioned, for these subjects and this setting, AA was useless and Wide S seemed to generally work well, though as I mentioned it too would occasionally lose capture and revert back to the abdomen - see the highlighted screenshot of the series below.

View attachment 99613

As Steve identified in testing, Nikon bird detection can have some issues with birds with long necks.

Wide area AF seems to me appropriate for your head shot of the swan, and as you report it worked.

Just pressing keys on a piano does not produce a tune - which keys in which order with what timing make a lot of difference.

Back to bird AF, probably 90% of bird species fit the detection criteria of Nikon bird AF - and maybe 10% do not. Steve specifically identified herons with long necks as a challenge.

I find AF subject detection zones on modern cameras in general a blessing though occasionally I find it necessary to take charge of which mode to change to when the AF does not perform as I anticipate.

In a way this is similar to taking charge of which metering mode to use, when, and which + or compensation to get the results I want.
Next Thursday if the weather performs I plan to photograph a sunset against a stunning backdrop.
My tried and tested method is spot metering from an area of sky away from the sun to get a mid tone where I want it rather than letting matrix guess which light level to expose for.

With metering there is the benefit of the histogram.
With sports (or any other "activity") test shots during any warm-up can help identify if AF is likely to do what I want it to do.

 

[dabhand16]

but the problem for sports is that even without subject detection the closest subject priority of those area boxes causes problems with so many different people out there on the field.

That's why I use a large single point with no detection or tracking modes. Back in my dSLR days the small dynamic worked well too but on mu Fuji I can't get an optimum DR box size. One is a bit too big and the next click down is a touch small. They do both work though.

Have you tried large single point with no SD or tracking?

 

[SCoombs]

That's why I use a large single point with no detection or tracking modes. Back in my dSLR days the small dynamic worked well too but on mu Fuji I can't get an optimum DR box size. One is a bit too big and the next click down is a touch small. They do both work though.

Have you tried large single point with no SD or tracking?

The reason that I replied to your comment by talking about the closest subject priority with area boxes is that there are not different size single point AF modes - there is single point or there are area boxes, so my best guess was that by talking about "large single point" you were talking about one of the area boxes - which has closest subject priority.

Based on this reply, I wonder if you are talking about something that exists on Fuji cameras but does not exist on Nikon cameras.

The only thing that I could imagine someone might call "large single point" on a Z8 is the small wide area box, which has closest subject priority.

 

[palmafrancescopaolo]

Ciao a tutti, seguo con interesse. Ho comprato la Z8 da due giorni entusiasta dei commenti letti nei vari forum proprio per le capacità AF, leggendo questa discussione mi sta venendo la paura di aver sbagliato acquisto.

 

[dabhand16]

so my best guess was that by talking about "large single point" you were talking about one of the area boxes - which has closest subject priority.

Based on this reply, I wonder if you are talking about something that exists on Fuji cameras but does not exist on Nikon cameras.

The only thing that I could imagine someone might call "large single point" on a Z8 is the small wide area box, which has closest subject priority.

Nope - not talking about an area box. On my Fujis I can change the size of the single point AF box. If the 117 AF points are set I can go from a single point to 9 points in a box in 3 clicks of a control wheel. If the 425 AF points are set I can have just one point or go to 25 in 6 clicks. Then the size of the AF box selected acts as a single point so if any part of the subject is in the box it will be in focus.

If I turn on face or eye detection it over-rides the size of the box I've set and uses the whole frame to track the (say) eye as if I move the camera so the box I set is off the subject, the focus point stays on the eye. Without the detection modes enabled I only see the box that I've set and not the focus points inside it.

I can also set the size of the zone (dynamic) mode. Instead of my D850 having IIRC 3 sizes that you click through, I only have one but I can change the size of it and can see the AF pints in the zone/box. They do dance around within the box and as I said the small size can work well.

I got fed up with waiting for the Z8 so I got a Z6ii and that Can't change the size of the single point AF, but I assumed that the Z8 with it's superior AF system and options could. If you can't do this I'd try a dynamic mode with no detection. D9 if you can with the short lens and D9 or D25 with the longer one. On my Fujis the Zone box is clearly shown where my Z6ii only has a few dots to show the dynamic area and they are red, so difficult to keep the subject in the box.