Stepper Motor

Is stepper motor (STM) the way to go in mirrorless lenses?
USM / SWM lens are known to be terribly slow to focus when used in mirrorless or DSLR live-view CDAF.
It doesn't have the accuracy for fast continuous AF tracking in mirrorless that uses CDAF either.
Would a hybrid CDAF & PDAF yield a solution?

Would Canon's Dual Pixel CMOS AF resolves the AF Tracking problem in mirrorless ?
And what is Nikon dong for it's newly launched Z6 & Z7 mirrorless in this regard?

Yes, mirrorless AF works best with STM type lenses. No Dual Pixel does not solve this which is why all of Canon's mirrorless lenses are STM
Nikon's S lenses for mirrorless are all Stepper motor lenses as are Nikon's DSLR lenses designated with the letter P

Sounds like there would be a problem for AF-S lenses adapting to Z7/Z6 via Nikon FTZ adapter especially for precise AF tracking with super telephoto lenses.
re: https://www.dpreview.com/articles/00397 ... es?slide=7

Which is exactly why I, as an amateur, won’t buy any more of Nikon’s supertele’s until this issue is clarified. (The 500PF might be an exception.) On one hand if Nikon’s existing superteles perform as well on mirrorless as they do on DSLR’s (though perhaps not to the potential if they had STM motors when used on mirrorless), that won’t be too bad because they’ll continue to work optimally on DSLRs and won’t lose any performance going to mirrorless. In other words you got what you paid for. But if their performance degrades significantly moving to mirrorless, that could be a problem for Nikon, I think.

That being said, even uber-expensive high-performance pro lenses have a limited market life. When I bought my 600E three years ago I hoped that it would remain top of it’s class for as long as 10 years. It’s beginning to look like that idea is wishful thinking as supertele lifecycles seem to be getting shorter; Consider Sony’s new “radically” designed and super light 400/2.8 and Canons rumoured 600MKIII replacement (the MKII wasn’t that old). Toss in the upheavals that mirrorless technology could cause and it’s becoming increasingly clear to me that supertele lifecyles are getting shorter. Perhaps that’s not much of a concern for a pro or well-healed amateur, but it could be a factor for the rest of us enthusiasts.

Just my random thoughts on the matter.

I am surprised that stepper motors are being used, Sony has moved to linear motors on their big lenses.

It's already been tested, at least on pre-production. The Nikon AF-S teles do not perform as well for moving subject tracking nor would they, the motors in those lenses are not designed for the types of focus movement that mirrorless on-sensor AF demands.

Mike in O wrote:I am surprised that stepper motors are being used, Sony has moved to linear motors on their big lenses.

Semantics in part, those two are not mutually exclusive.

Here’s a link to an article that provides a bit of info on lens focusing motors:

Lens Focusing Motors

Joe

SantaFeJoe wrote:Here’s a link to an article that provides a bit of info on lens focusing motors:

Lens Focusing Motors

Joe

Thanks Joe, the comment section was an also worthwhile read.  Cheers Mike

E.J. Peiker wrote:Yes, mirrorless AF works best with STM type lenses.  No Dual Pixel does not solve this which is why all of Canon's mirrorless lenses are STM
Nikon's S lenses for mirrorless are all Stepper motor lenses as are Nikon's DSLR lenses designated with the letter P

[ul]
[li]E.J., is this more of an issue for video than for stills?   My DSLR lenses are spot on for focus with my M5 mirrorless with the adapter.  Could we expect the Nikon and soon to be Canon mirrorless bodies to do well with DSLR glass for Stills, even with fast moving subjects.[/li]
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It's not about them being spot on or not, it's how fast they can get there and whether or not they can track motion, especially motion towards or away from the camera.  That is an issue for both video and action photography stills.

Understand, Thanks. The new lens lineup for the Canon R includes 2 USM lenses and 1 STM. Does this mean they have found a way to improve the performance of the USM for mirrorless?

rtvernick wrote:Understand, Thanks.   The new lens lineup for the Canon R includes 2 USM lenses and 1 STM.    Does this mean they have found a way to improve the performance of the USM for mirrorless?

The new lens lineup at this point is only rumor - we will know in a few days what the true announcements are.  USM motors are fine for static scenes and relatively OK for motion parallel to the lens elements where the relative distance between subject and camera isn't changing much or changing slowly.  They generally fall apart for action coming towards or away from the camera causing some hunting and slight to moderate missed focus.  I would not expect action oriented lenses in the future to have USM motors but rather linear stepper motors.  Of course Canon could have had a breakthrough, we'll know soon enough.