Z8's autofocus chases like crazy with FTZ II adapter

[fredscal]

Hi.

I just made the leap to mirrorless, purchasing a Nikon Z8.

My idea was to get a new Z-mount 24-120mm, and keep my other F-mount lenses, at least as long as I kept my D810 as secondary body. Some of those F-mount lenses I may wish to keep indefinitely, because I picked them very carefully for a variety of qualities only interesting to the art photography geek I fancy myself to be. I was planning to use those last generation F-mount lenses with the Z8 on a regular basis, though.

So, Amazon delivered my Nikon FTZ II adapter yesterday and I just tried to mount my Nikkor AF-S 50mm f/1.8 G, Nikkor AF-S 85mm f/1.4 G, and Sigma 12-24mm f/4.5-5.6 DG HSM on the new Z8 body.

The thing is, the AF chases like crazy, sometimes needing several full-range back-and-forths before locking on to the subject, even when the new focus distance is actually pretty close to the previous one - even when I refocus on the same subject at the exact same distance ! Whether it has to push or pull focus doesn't seem to make much of a difference, and all my test subjects were stationary.

I was told that, while the FTZ II adapter wouldn't work well with older F lenses, it should work pretty well with the most recent ones. I wasn't expecting much of an improvement in AF speed over my D810 combos (maybe just a little or maybe none at all) but I certainly didn't expect it to be this much worse.

Is there anything I can do to make it better ? Some deep settings, maybe ?
Or is it possible that there's a problem with either the adapter or the body ?

I didn't plan to replace all my lenses. Especially when I can't sell the older ones because then I'd have to replace my backup D810 as well.

Ok, I'll stop here before babbling about my whole life.

Thanks for any insight.

Edited June 22 by fredscal
i always edit my posts a hundred times

[fredscal]

OOPS !!! I DIDN't IDENTIFY THE PROBLEM PROPERLY. PLEASE IGNORE THE POST ABOVE (I can't edit it anymore) AND READ THIS INSTEAD :

Hi.

I just noticed my Z8's AF does a lot of back-and-forths in low light. My D810's AF, in comparison handles low light much better. I would have expected the opposite.

Normally, that's not too much of a problem, because the Z8's AF is so much faster than the D810, it still locks on faster even with the chasing.

But then I'm using some last generation F-mount lenses on my Z8, with the FTZ II adapter, either because I fancy myself an art photography geek who spent a lot of time picking his favorite lenses for various subtle qualities, or (and mostly) because I'm keeping the D810 as a backup body.

Anyway, when mounting F lenses on the Z8, the AF's chasing becomes a real problem, because then the Z8's AF gets about as slow as the D810's.

Is there anything I can do to improve the Z8's AF performance - mainly reduce those full-range back-and-forths - in low light ? Are there some settings to tweak? Are some AF modes better at handling this? I always use the point AF then reframe technique which I know is very old-school but I guess I'm old.

The only thing I've tried so far is activate the built-in AF assist light, and it doesn't help.

Thanks

Edited June 22 by fredscal

[ilkka_nissila]

You might get more responses on the Nikon forum (although it is kind of miscategorized now as a DSLR & Film cameras subforum, most of the discussion there today is on mirrorless cameras).

 

In low light, some of the older AF-S Nikkors (and various small primes) don't focus as well as native Z mount lenses or even some late-generation AF-S (or AF-P) Nikkors that have newer electronics and focus motors. There can be a lot more jitter or hunting than with newer or with native lenses. This is due to the lenses designed to work with phase-detect AF sensors in DSLRs only (contrast-detection is not used by DSLRs except in Live View in models other than the D780). The Z cameras (and the D780) use a combination of phase- and contrast detect AF and in low light the contrast detection is probably used with greater role, which then results in the hunting you see in low light when using these older lenses. The Z lenses are designed to work well with contrast- and phase-detection AF and typically have stepper motors or in a few cases, some other types such as the voice-coil motors in the 400/2.8 and 600/4. When using native Z lenses, this hunting or jitter in the focusing in low light is largely absent, though there are still situations where the camera can't nail the focus quickly (when the focus is way off, and the subject is closer to the camera than the focused distance).

 

So gradually to get the best AF performance in low light you'll probably want to get some new Z lenses. F-mount lenses can still be used and some of them focus really excellently on the Z8 (e.g. 200/2 II). However, one can't really get away from the fact that mirrorless cameras have different autofocus technology which places different demands on the lenses as well and these are met in the Z mount lenses.