When Nikon started shifting over from the screw-drive autofocus system of their regular F mount AF lenses to their AF-S system they started adding autofocus motors inside the lens itself. One of the key selling points at the time was that no matter which camera you were using, the lens would always rack from minimum to maximum focus at the same speed as the motor was in the lens itself.

Along comes Z mount with adapted F mount lenses and this didn’t hold true anymore, with them generally spinning slower (albeit achieving similar overall results due to the more advanced AF system). Not anymore, though. According to this video from photographer Dariusz Breś, Nikon seems to have gotten AF-S lenses spinning just as fast on the Nikon Z9 as they did with their DSLRs.

You can clearly see in Dariusz’s video above that the focus is racking from infinity to minimum focus distance and then back to infinity way faster on the Nikon Z9 than it does with the Nikon Z6 II (and presumably just about every other camera in the Nikon Z system). Dariusz believes that the difference is simply down to the fact that the Z9 has much greater computational speed and can send those signals to the motor inside the lens more quickly, as he writes (Google translateD) on his website:

It looks like the lenses attached by the FTZ2 on the Nikon Z 9 are at full speed. I checked it with the Nikkors and the Sigmas. The difference is quite significant.

In the movie Nikkor 300 2.8 VR + Z 6II and Z 9. I also checked the Z 7II and it performs the same as the Z 6II. Where does such a difference in engine operation come from? The Z 9 has a faster matrix and processor, I think that’s the reason.

Does it matter in practice? in fast action, yes, because even when the lens loses the object, it can return quickly. In ordinary photography it does not matter.

So, basically, Z mount cameras up until this point were essentially crippled when it came to using adapted F mount lenses. Nikon claimed otherwise, stating that you’d get the same performance with F mount lenses on Z mount cameras using the FTZ adapter as you would using them on a native F mount DSLR. And when it comes to overall performance, taking the entire autofocus system into account, it may actually be true. After all, every part of the process that doesn’t involve the motor actually spinning is much faster with the newer technology inside Nikon’s mirrorless camera systems.

But the actual speed of the focus motor was definitely slower with Z mount cameras than it was with DSLRs before the Z9 came along. And this isn’t the first time this topic’s come up, either.

Wildlife photographer Steve Perry made a video about the Z9 way back in January that touches on this very topic (starting at 2:41), comparing the motor speed of various AF-S telephoto lenses on the Nikon D850, Nikon Z6 II and Nikon Z9 using both the FTZ and FTZ II adapters and his results were pretty similar. And it’s not that the Nikon Z9 is particularly quick (I mean overall, yes, it is, but not in how fast it spins the motor of an AF-S lens) but that the rest of the Z lineup are pretty slow. As you’ll see, Steve’s results with the Z9 were virtually identical to those with the D850.

Whether it is a case of raw computing power in the Nikon Z9 that accounts for this speed increase or simply a more optimised algorithm that allows it to spin AF-S lenses faster is unknown. If it is the latter, hopefully, we’ll see at least some performance increases with adapted lenses in other cameras in the Nikon Z system at some point through future firmware updates. But for right now, if you’ve got a Z9 – or you’re sitting on a ridiculously long pre-order list and still waiting for it – then it may be worth holding onto those F mount AF-S lenses!

[via Nikon Rumors]