Z8 / Z9 Video Autofocus using AF-S and third party lenses through FTZ adapter

Just trying to get a feel for how good the autofocus is of this body specifically with lenses through the FTZ adapter, if anyone has any experience on this? I have a few F mount primes I would like to continue to use for video (AF-S lenses) like the 24mm 1.4G. I also am hoping to get a reasonable (though don't expect focus to be as good as native or non adapted glass) result with the sigma 14/1.8 art lens for video. I manually pull focus with this at the moment with a small monitor on the hotshoe. Has anyone tried sigma glass on the Z9 (or 8) to give any personal insight into this? I'm planning on continued use of the sigma 14/1.8 lens for video until sigma or nikon release a native 14/1.8 prime lens. I am planning on picking up a Z8 so this information will likely translate across for the most part.

I don't have that 14mm lens but I have 3 Sigmas (150mm f/2.8 OS macro, 150-600mm f/5-6.3 Sport and 500mm f/4 Sport) that I still own and all 3 work perfectly on my Z9 via the FTZ.

Not Sigma specifically, but have a 500mm PF that works very well indeed, fast, accurate AF with my Z9. I also have an F-mount Tamron SP 35mm f1.4 that works extremely well on my Z7 (noticeably better AF accuracy/consistency wide open compared to my D850). Haven’t tried it on my Z9 yet but I expect it will at minimum perform as well. Many, many people use adapted F-mount glass with their Z’s, so I expect you will get plenty feedback here.

There are no negatives other than if no in-lens motor the body will not auto focus it.
All that happens on either type of lens is that the body sends signals to the motor in the lens on how far to turn the focus motor.

They're are lots of potential positives.
The first is human error. There are numerous things on which DSLR in body AF detection may not work well.
I find following Nikon guidance produces very consistent and accurate AF and that "complainers" generally expect this type of AF system to work on subject types where Nikon caution it may not - and then do not blame themselves.

Mirrorless AF detectors are on the sensor and have fewer subject types potentially able to cause poor focus - leading to a higher success ratio without studying the guidance for success.
The AF motors in Nikon ML lenses combined with the much greater information transfer between body and S lens can perform a little more accurately with a higher "perfection" result on a wider range of subject types. Even so overall Nikon AF-S F mount lenses can on average perform a little better than on a DSLR body as AF works well on more subject types.

Digressing several Nikon Z lenses have two AF motors in the lens - a few Sony have 3.
This enables high optical quality at a wider range of AF distances than with some F mount lenses.
Nikon are claiming even more accurate AF with lenses like the 400 f2.8 and 600 Z lenses - presumably due to improved technology in these expensive lenses.

Some other brand lenses can be used via adaptors which are able to interpret Nikon body signalling the with reasonable success - generally not as well as a Nikon Z lens - but useful where Nikon are slow to release some promised lenses "for Christmas" (but which Christmas?) such as the 200-600.

Can't say about Z8/Z9 but the F mounts behave wonderfully on the Z7s provided its not real low light. The lower F stops of the 1.4s do make a difference. The better AF precision and repeatability of the Z7II convinced me to give up the D850. I don't regret it for a minute as getting way from the calibration thing was lovely. I can only imagine the Z8/Z9 is even better.

Thank you. So you feel they work well in terms of reliability in video, no searching and loosing subject etc like previously with poor DSLR AF (which I never used).

You will get clicking noises recorded in video.

Better buy z lenses for best performance

I almost excusively shoot stills not video so not the one to answer that question. I wouldn't expect any issue with the Z9/Z8 except maybe AF motor focussing noise(s) with some lenses - but I haven't tried video with those lenses. Busy right now with other stuff but now you have mentioned the idea I will give Z9 video a try with the 500 and the 150-600 sometime!

My 50mm 1.4 pre-art has a feature what I call jackhammer focusing. Micro adjustments are herky jerky, and somewhat noisy. I think this stuff goes on a lens by lens basis. My 150-600 does not do this at all.

I think you both have a point here. It might be a case by case basis. With the 14mm 1.8 sigma art, I focus on objects quite close up in video mode and as I say, until now I just manually pull focus. Going forward though, the helping hand of the Z8's video AF would be very welcomed. Hopefully it will not pulse in and out of focus constantly like with DSLRs as this is the reason I manually pull as is, it is very distracting to see in video as you can imagine. This is what I am hoping. With a lens like this it has a great dof of course, but less so in close range. I hope though this makes it easier for the AF system. A slight noise will be okay as I can move Mic away.

This leads me to another question. With the Z9 (Z8), can the speed of refocusing be changed? What I mean by this is, when we tap the back screen to change the focus to a different subject, e.g. face, I noticed in most youtube videos it happens quickly - too quickly if one is trying to be cinematic about it. Are there any menu settings that allow a soft pull (think cinema), rather than this sudden abrupt focus change.

As others have mentioned, various F mount lenses are going to be noisy when focusing or when the VR is active, much moreso than the Z mount lenses I own. It's definitely a case by case situation. Also, the "E" series lenses with electronic aperture are preferred. Using an external mic helps a little, but you really need to consider an off-camera mic when using most F mount lenses for most situations.

To your second question, yes, the Z9 and the Z8 both have two adjustments for AF focusing in video...speed and delay before refocusing. Both these controls seem to provide a good choice of options, depending on the type of movement what you're shooting involves.

I use both Nikon and Sigma F mount lenses with my Z cameras - Video AF works very well - but noise can be captured. Z lenses too can generate clicking noises (my experience is limited to 28mm f2.8 Z).

Focusing speed can be controlled although I have never used it.

The DSLR experience cannot be compared except if you have a D780. DSLRs used contrast detect focus in video which is unworkable.

This is good. I really want a slow change of focus without the whip that occurs in reviews I've seen. Is this specifically in the video shooting setting menu? I wonder how the Sigma 14 will work. Hopefully i'll find out soon!

The controls are G6 and G7 on the Z9 and they're in the Shooting Banks menu's, so you'll be able to have different setups for each of the 4 shooting banks. The range is from -5 to +5, so quite a bit of control over the speed, from quite slow to quite fast. Someone did a video on this subject a while back and it seems to me that the slow focus took something like 30 seconds and the fast seems to me was less than a second. I have it set on -3

Strike that about having a non-Nikon AF lens...I forgot that I sold it a while back. Down to an Irix 11mm F4 and Rokinon 8mm and both are manual focus.

Here is a sample video showing the fastest speed, +5 and the one I typically use, -3. -5 is so slow that I thought it wasn't working...so it may indeed be close to 30 seconds. :) This was shot with 24-120 at about 85mm in 1080p30. The AF tracking sensitivity setting was set at the middle setting (4) so there is a slight delay before it starts to refocus.

Z9 AF Speed Sample

Nice - appreciate you showing me that, does it work also when you tap to refocus on the new subject without moving the camera, in that you can have those slower pulls?

The AF Speed setting does NOT apply when you tap the LCD to choose a new focus point. By the way, there is a sub setting under setting G6 that allows you to select whether or not the setting applies just when "recording" or "always", the latter meaning when just viewing through the viewfinder or via the LCD and not actually recording. Unfortunately, there is not, a setting to allow making the setting also apply to touching a new focus point while recording. However, if you move the focus point to a new location via the joystick, it does change focus based on the speed setting. The subselection for "Always" or "Recording" applies to focus point changes via the joystick.

So helpful this thanks. So it seems there is a work around in that we can move the joystick and get the effect. Slow focus pulls are one of the subtle cornerstones of good footage!

You're quite welcome, learned a couple new things myself in looking into this. I think adding a menu setting to select whether a selecting a focus point/subject via the touchscreen is instantaneous or adheres to the AF speed setting G6 would be valid feature request. @thom are you in the building???