AF consistency of Z mount lens vs F mount lens

[Doug A.]

Perhaps this has already been discussed before, but I couldn't find it. I have only had my Z7II for a few months, so I'm still learning its AF system. This morning I photographed my church's Easter Egg hunt event. I have both a D850 and a Z7II. I do not have any Z mount lenses. I used my Z7II + FTZ II + 24-70mm AFS lens. I don't do much in the way of wildlife photography but those kids during the Easter Egg hunt were analogous to BIF. Very quick and erratic with their movements. The Z7II being smaller, quieter, and lighter weight was my choice so that I could be a little more inconspicuous. I used primarily the Wide Area AF - Large for people faces as that mode has worked well for me when photographing people. Unfortunately, I was having lots of trouble consistently getting my shots to be in focus. I shot in short bursts (3-5 shots) using continuous AF and BBF and my "hit rate" was less than 50%. Sometimes the camera just could not acquire focus on their face/eye from the start of the burst. Sometimes the camera would lose focus mid burst even though it continued to track the kids face. Sometimes it would totally focus on something in the background even if there were no other faces in the Wide Area-Large box. Is this more a symptom of using the wrong AF mode for erratically moving subjects or is it more a symptom of using the FTZ adapter with an F mount lens. The AF speed was plenty fast enough for the job, so in that regard I have no issues. I know from previous experience my D850 would have a higher keeper rate as it has done a better job staying on target, but that rig gets heavier every time I pick it up and the mirror slap now sounds like a cannon going off compared to the Z7II. I will say the shots from the Z7II that were in focus were beautifully exposed with wonderful color, saturation, and tone SOOC.

 

[Butlerkid]

Using the FTZ II adapter with F mount lenses is not the problem.

Choosing appropriate AF area mode is more likely the problem. Did you have subject detection on? Was there more than one face in a frame? If so, the camera would not know which face to focus on and might try to move back and forth between faces. How large were the faces in the frame? Large enough for the focus system to lock on? Focus needs to lock on before it can track.

Probably the kids were running around and looking down most of the time......not looking at the camera and seldom had their faces visible for the camera to detect their eyes. More likely it was the side and back of heads and hair. If subject detection wasn't working, turn it off. I might have tried a small enough f stop to give a good DOF and maybe Wide area small (similar to group on a DSLR) and kept the focus box on the subject. If that didn't work I'd try single point or 1x1 custom and try to keep it on the subject's head.

 

[abc123brian]

Your results sound worse than typical and not as good as I’d expect, but it does tend to be an area the first and second gen cameras struggle some. Based on what you said, you were using AF-C, Large Area with subject detection and this is what I’d use in the situation as well. I will say the AF performs worse when the light is low or when the exposure is darker, or the there is a lack of contrast. How far off are you talking on the focus miss? Were you at F/2.8 with a shallow depth of field already? It is possible the camera would have performed better with subject detection off. When I use it for wildlife I typically keep subject detection off and it does fairly decent. I did shoot an event earlier this year and had subject detection on and felt the camera missed more than it should. The misses I saw were not far off but enough to notice it wasn’t on the eye.

 

[Doug A.]

I was using anywhere from f2.8 to f5.6. It was a partly sunny day. I was using Auto ISO in aperture priority with a minimum shutter speed of 1/250 sec. Here is an example of a burst where it would just totally lose focus lock on the woman's face and appear to focus on the background.

How far off are you talking on the focus miss? Were you at F/2.8 with a shallow depth of field already?

 

[abc123brian]

I was using anywhere from f2.8 to f5.6. It was a partly sunny day. I was using Auto ISO in aperture priority with a minimum shutter speed of 1/250 sec. Here is an example of a burst where it would just totally lose focus lock on the woman's face and appear to focus on the background.

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It looks like the camera thought the kid with the dinosaur hat was more interesting. It appears it moved focus when his arm got closer to the woman’s face, but there really is no reason it should have done that. With the exception of the 500mm PF and 24mm PC, my lenses are all Z mount and I find the Z7ii does do things like this, but not quite as frequent as you described here, so I don’t think it’s an issue with you using F mount lenses. It is possible it exaggerates the issue some. Do you have the most recent firmware? I think it was supposed to help address this issue.

 

[fcotterill]

Intriguing challenges, which I also met with using my Z7. I also found single point the more flexible to try and track moving subjects. The constraint on in-focus images then depends much more on the photographer's tracking ability, because the more auto modes can miss the eye etc.

The scope of Custom settings gives significant advantage of your D850 in these situations, to "hand-off" the AF between 2 or more AF modes. Group and Dynamic 9 with Single-point give much more near instant flexibility to track a moving subject and avoid grabbing the background.

AFmode+AFOn is your friend for this D850 Custom setup to assign AF modes to Pv, Fn1, using BBAF. Unfortunately, Nikon has refused to add these Custom options to any Z camera (besides the Z9) so the photographer is hamstrung to using only 1 AFmode at a time, despite the many options, for an active subject.

On more technical issues, this interview with Nikon engineers includes some insights into the differences between the AF of the Nikon DSLRs and Z7

 

[dabhand16]

I was using anywhere from f2.8 to f5.6. It was a partly sunny day. I was using Auto ISO in aperture priority with a minimum shutter speed of 1/250 sec. Here is an example of a burst where it would just totally lose focus lock on the woman's face and appear to focus on the background.

View attachment 58653

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I think you were using the wrong focus modes for these sujects in this situation. Steve is always saying that the Z cameras need to be in the right mode for the situation and you have just proven he is right. You say that with the /d850 you had a better keeper rate. What focus mode were you using then? I'd have been in single spot for these shots with a Z camera, maybe group or small dynamic with a D850.

 

[Doug A.]

With my D850 I have had better success with tracking faces using 3D AF mode with face tracking turned on (custom setting a4).

You say that with the /d850 you had a better keeper rate. What focus mode were you using then?

 

[Doug A.]

Yes.

Do you have the most recent firmware?

 

[abc123brian]

I think you were using the wrong focus modes for these sujects in this situation. Steve is always saying that the Z cameras need to be in the right mode for the situation and you have just proven he is right. You say that with the /d850 you had a better keeper rate. What focus mode were you using then? I'd have been in single spot for these shots with a Z camera, maybe group or small dynamic with a D850.

Why would using one of the two focus modes that include human subject detection be the wrong mode to use to shoot human subjects? In the example photo shared, the subject wasn’t even moving and the the subject tracking wondered to the kid passing by behind the subject. This seems like an ideal scenario for subject detection to be used for this camera that it should be able to handle. I will agree non subject detection would have likely been more successful given the issues mentioned, but reverting back to those modes shouldn’t be necessary in this situation.

 

[Doug A.]

I thought it was the best AF mode for the scenario as well. I have shot several other events with people moving around using my 85mm G lens and not experienced this frustration. Thus my original ask about is this a F mount lens issue vs Z mount lens issue. I 'm sure the 24-70mm Z mount would perform better, but its crazy expensive.

Why would using one of the two focus modes that include human subject detection be the wrong mode to use to shoot human subjects? In the example photo shared, the subject wasn’t even moving and the the subject tracking wondered to the kid passing by behind the subject. This seems like an ideal scenario for subject detection to be used for this camera that it should be able to handle. I will agree non subject detection would have likely been more successful given the issues mentioned, but reverting back to those modes shouldn’t be necessary in this situation.

 

[Venkatesh VT]

We had serious issues with Z9 & 500 PF during our recent 10 days birding trip . Suddenly it would show F — instead of F 5.6 & also show err. It invariably used to happen very frequently & I doubt the conveyer was the issue
We had earlier sent it to Nikon Service centre for the issue & they could not find any thing wrong
We missed many shots & it was totall a disappointing experience

 

[EricBowles]

Why would using one of the two focus modes that include human subject detection be the wrong mode to use to shoot human subjects? In the example photo shared, the subject wasn’t even moving and the the subject tracking wondered to the kid passing by behind the subject. This seems like an ideal scenario for subject detection to be used for this camera that it should be able to handle. I will agree non subject detection would have likely been more successful given the issues mentioned, but reverting back to those modes shouldn’t be necessary in this situation.

Subject detection does not work all the time. When it is not working, the camera is essentially just in Auto mode - find something with contrast. That removes all control over the focus target.

Subject detection is to assist the photographer - not a panacea to be used all the time. Just as Doug was able to focus with the D850, those same modes or similar modes would likely do a good job if subject detect is not working. It really depends on the situation. I've tested subject detect and had it successful 95% of the time - but was in the same range with it turned off or using my D850. But handling the 5% with focus missed was a challenge with subject detect mode, so by turning off subject detect, it's easier to use Single or Small and get the shot.

Likewise for bursts, sometimes during a burst the camera will acquirer focus. But just because one image is in focus does not mean the camera actually acquired good focus on the subject - just that it focused at the right distance. A lot of misses look like they were close to correct focus. The camera is looking for the focus target on every shot in a burst, and even if it has the right subject initially, it has a wandering eye that is always looking for a better focus target. Maybe it's the other eye, the other person if there are two people, or something that looks like an eye behind the subject.

In this case there are multiple subjects, contrast and patterns in the background near the subject, and faces and eyes that are constantly moving and looking away from the camera. In the sample frames above, there are no eyes looking at the camera, no catchlight, and the faces are not looking at the camera. If that is the kind of shot you want, you don't need face or eye detect because the eye is an incidental target. Single area would work very well. Dynamic would work well if you were concerned about subject movement. Wide small would work and largely eliminate a miss that picks up the background.

One more thing - the shutter speed was pretty slow for any kind of active photos at 1/250. For event photos, I usually try to keep a shutter speed of 1/400 - 1/640.

 

[dabhand16]

Why would using one of the two focus modes that include human subject detection be the wrong mode to use to shoot human subjects? In the example photo shared, the subject wasn’t even moving and the the subject tracking wondered to the kid passing by behind the subject. This seems like an ideal scenario for subject detection to be used for this camera that it should be able to handle. I will agree non subject detection would have likely been more successful given the issues mentioned, but reverting back to those modes shouldn’t be necessary in this situation.

Too many human subjects for me with people AF large. The camera is not so smart in knowing who you are shooting.

 

[abc123brian]

Subject detection does not work all the time. When it is not working, the camera is essentially just in Auto mode - find something with contrast. That removes all control over the focus target.

Subject detection is to assist the photographer - not a panacea to be used all the time. Just as Doug was able to focus with the D850, those same modes or similar modes would likely do a good job if subject detect is not working. It really depends on the situation. I've tested subject detect and had it successful 95% of the time - but was in the same range with it turned off or using my D850. But handling the 5% with focus missed was a challenge with subject detect mode, so by turning off subject detect, it's easier to use Single or Small and get the shot.

Likewise for bursts, sometimes during a burst the camera will acquirer focus. But just because one image is in focus does not mean the camera actually acquired good focus on the subject - just that it focused at the right distance. A lot of misses look like they were close to correct focus. The camera is looking for the focus target on every shot in a burst, and even if it has the right subject initially, it has a wandering eye that is always looking for a better focus target. Maybe it's the other eye, the other person if there are two people, or something that looks like an eye behind the subject.

In this case there are multiple subjects, contrast and patterns in the background near the subject, and faces and eyes that are constantly moving and looking away from the camera. In the sample frames above, there are no eyes looking at the camera, no catchlight, and the faces are not looking at the camera. If that is the kind of shot you want, you don't need face or eye detect because the eye is an incidental target. Single area would work very well. Dynamic would work well if you were concerned about subject movement. Wide small would work and largely eliminate a miss that picks up the background.

One more thing - the shutter speed was pretty slow for any kind of active photos at 1/250. For event photos, I usually try to keep a shutter speed of 1/400 - 1/640.

I’m not disagreeing with what you’re saying here, but this seems like a perfect use case for subject detection. If it cannot keep up with a mostly stationary subject kneeling on the ground, it doesn’t seem very useful. I would say Wide Area Small would have been more successful, but many complain about the Zii cameras wanting to drift to the background. I will admit I primarily use the Z9 for this type of shooting as it doesn’t drift around like this. Where I see subject detection issues with it, it’s moving to the eye in the reflection in the water of a bird, but even this isn’t that common. This seems to be more an issue with subject detection on the first and second generation Z6/Z7 cameras not being as sophisticated as others.

 

[abc123brian]

Too many human subjects for me with people AF large. The camera is not so smart in knowing who you are shooting.

Wide Area Large is not really that large of a box, at least for the composition shown in the sample. I could see it as an issue if the box was over all three subjects instead of primarily over the woman on the right.

 

[EricBowles]

I’m not disagreeing with what you’re saying here, but this seems like a perfect use case for subject detection. If it cannot keep up with a mostly stationary subject kneeling on the ground, it doesn’t seem very useful. I would say Wide Area Small would have been more successful, but many complain about the Zii cameras wanting to drift to the background. I will admit I primarily use the Z9 for this type of shooting as it doesn’t drift around like this. Where I see subject detection issues with it, it’s moving to the eye in the reflection in the water of a bird, but even this isn’t that common. This seems to be more an issue with subject detection on the first and second generation Z6/Z7 cameras not being as sophisticated as others.

I certainly agree. I think subject detect would be my primary choice as well. But with my Z6 and Z7ii, I find I might get 95% success, but still have misses. My point is simply that rather than troubleshooting misses, having a solid plan for a workaround is probably more effective. I have not had a problem with the wide modes picking up the background when the subject fills a large portion of the frame, but I have shot 10's of thousands of images and it may be my technique is slightly different. I certainly have seen it happen when subjects are distant or the subject is close but unclear with little contrast.

 

[Chris K]

My experience is, if I have eye detect AF I'm going to hit the shot almost 100% of the time. If I don't, my hit rate is directly tied to the AF capabilities of the camera. My Z9 is good, and my Z6 was decent. But the Z9 without eye detection is far worse than my GFX100S with eye detection.

I do everything I can to make eye detection work when shooting people, and I recognize that I'm going to have to work much harder (and accept worse results) when I'm handling AF myself.

I haven't forgotten how to shoot without eye detection, but man, oh man does it make life easy.

 

[Guy Harr]

Maybe all these features that make it easy make us easy to become complacent and not do our best in technique. We start to expect the camera to read our intent which it never was designed to do. What would you do without these features to get the shot?

 

[Chris K]

Maybe all these features that make it easy make us easy to become complacent and not do our best in technique. We start to expect the camera to read our intent which it never was designed to do. What would you do without these features to get the shot?

Subject detection is designed to--and genuinely does--read my intent. If I'm pointing my camera at a bird in a pond, it's very rare I intend to take a photo of the pond instead of the bird. It truly is a panacea. Even the matrix metering we've all been using for 30+ years is more frequently fooled than subject detect AF!

I'll use all tools available to me to their best application. I know how to use area C-AF, manual exposure, and manual white balance, but there's no reason to avoid advanced tools simply because they might not always provide benefit. I'm being no more complacent by using fancy autofocus than I would be if I were using a screw gun to hang drywall instead of a screwdriver.

 

[dabhand16]

but there's no reason to avoid advanced tools simply because they might not always provide benefit.

I have to disagree with this. We are all different I know, but my philosiphy has always been use the best tool for the job, not pick a tool that ought to be able to do the job.