A Bit More About the New “Big White” Lenses Coming from Canon [CR3]

nchoh

EOS RP
Apr 3, 2018
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Re: A Bit More About the New Big White Lenses That Are Coming

Kit. said:
nchoh said:
A stepper motor is controlled very differently than other types of motors. A stepper motor has steps, hence the name. Each step is a fixed angle. For example a stepper motor with 365 steps would move precisely 1 degree for each step called and move forward or backward a precise amount based on the screw. So the difference between a stepper motor performance versus other types of motors is because the stepper motor is able to take different instructions.
And how is it different from the AF protocol EOS camera uses with any other EF lens?
With DPAF the STM focus algorithm would be like; move forward 22 steps fast, move forward 1 step slow.

A usm lens algorithm could be like; move forward half the distance, check focus, if front focused, move forward half of remainder, if back focused, move back half the distance. Repeat above. keep repeating until in focus. When the lens is slow or the focusing sensor is having a hard time, this hunting is apparent to user.
 

Kit.

EOS 6D MK II
Apr 25, 2011
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Re: A Bit More About the New Big White Lenses That Are Coming

nchoh said:
Kit. said:
nchoh said:
A stepper motor is controlled very differently than other types of motors. A stepper motor has steps, hence the name. Each step is a fixed angle. For example a stepper motor with 365 steps would move precisely 1 degree for each step called and move forward or backward a precise amount based on the screw. So the difference between a stepper motor performance versus other types of motors is because the stepper motor is able to take different instructions.
And how is it different from the AF protocol EOS camera uses with any other EF lens?
With DPAF the STM focus algorithm would be like; move forward 22 steps fast, move forward 1 step slow.
A usm lens algorithm could be like; move forward half the distance, check focus,
Why?

Why not just move the equivalent of 22 STM steps "fast" and check if you are in focus now? Looks exactly what the big white lenses are doing.
 

nchoh

EOS RP
Apr 3, 2018
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113
Calgary
Re: A Bit More About the New Big White Lenses That Are Coming

Kit. said:
nchoh said:
Kit. said:
nchoh said:
A stepper motor is controlled very differently than other types of motors. A stepper motor has steps, hence the name. Each step is a fixed angle. For example a stepper motor with 365 steps would move precisely 1 degree for each step called and move forward or backward a precise amount based on the screw. So the difference between a stepper motor performance versus other types of motors is because the stepper motor is able to take different instructions.
And how is it different from the AF protocol EOS camera uses with any other EF lens?
With DPAF the STM focus algorithm would be like; move forward 22 steps fast, move forward 1 step slow.
A usm lens algorithm could be like; move forward half the distance, check focus,
Why?

Why not just move the equivalent of 22 STM steps "fast" and check if you are in focus now? Looks exactly what the big white lenses are doing.
I am explaining how it works in really basic, off the top of my head... I don't know the precise details of how it is implemented.

Yes, it could move precisely to the point as DPAF makes the exact distance known immediately. But the smoothness of how it focuses suggests that there is a bit of slowdown at the end... kind of like how Apple pioneered the bounce effect rather than a hard stop... psychologically easier and more comfortable for the brain.

But what I was explaining was the difference of STM lenses with DPAF versus other types of lenses.
 

Kit.

EOS 6D MK II
Apr 25, 2011
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Re: A Bit More About the New Big White Lenses That Are Coming

nchoh said:
I am explaining how it works in really basic, off the top of my head... I don't know the precise details of how it is implemented.
USM is a version of a stepper motor that makes more than 20000 small steps per second. Precise positioning with USM is easy.

What may be hard with USM is slow continuous focus shift without slowing down its stepping frequency into audible sound range. I.e. USM may be a bad solution for video autofocus.
 

nchoh

EOS RP
Apr 3, 2018
208
113
Calgary
Re: A Bit More About the New Big White Lenses That Are Coming

Kit. said:
nchoh said:
I am explaining how it works in really basic, off the top of my head... I don't know the precise details of how it is implemented.
USM is a version of a stepper motor that makes more than 20000 small steps per second. Precise positioning with USM is easy.

What may be hard with USM is slow continuous focus shift without slowing down its stepping frequency into audible sound range. I.e. USM may be a bad solution for video autofocus.
Technically not, but with technological improvements, the package may be equivalent. and I get your point.
 

fullstop

EOS 6D MK II
Apr 23, 2018
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Re: A Bit More About the New \

(Ring-) USM AF drive and STM AF drive are technically different with different characteristics. They need different ways of addressing/communication/commands.

As anyone can tell by simply comparing it, USM EF lenses' AF performance in DSLR mode is clearly better than in LiveView/mirrorless mode, irespective whether it is DP-AF - at least in all Canon implementations so far. This does not come as a surprise, since USM EF lenses where all designed for mirrorslapper operation with separate AF unit.

So far, STM lenses are better suited for operation in LiveView/mirrorless/DP-AF mode. Not sure, whether EF/USM AF performance can be improved by future, smarter algorithms/firmware or not.
 

neuroanatomist

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Jul 21, 2010
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Re: A Bit More About the New \

STM lenses are optimized for video (slower, quieter, smoother focus) and STM motors are better suited to consumer lenses because they are cheaper to produce than ring USM motors.

If Canon does use a new mount for FF MILCs, they're almost certainly going to release L-series lenses to accompany those cameras. When those L-series lenses have ring USM motors in them, that should (but knowing this forum probably will not) put an end to this bullsh!t about STM being optimized for mirrorless.
 

fullstop

EOS 6D MK II
Apr 23, 2018
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Re: A Bit More About the New \

"STM" and similar electromagnetic linear drives are better suited for mirrorless/on-sensor PDAF systems. Just check Rogers list ... https://www.lensrentals.com/blog/2016/04/a-look-at-electromagnetic-focusing/

Sony, Fuji, Zeiss (Batis) - all using a lot of Linear Electromagnetic AF drives, not only for low-end consumer lenses but also for big, "hi-end" lenses like Sony GM or Zeiss Batis.

Dual, triple, quad Linear Electromagnetic AF drives rulez for mirrorless operation. I would not be surprised, if Canon "EF-X" lenses will also be equipped with LEM AF drives, especially the "L class" ones. In combination with future, improved implementations of Canon DP-AF or Quad-Pixel AF it is something to look forward to.
 

neuroanatomist

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Jul 21, 2010
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Re: A Bit More About the New \

fullstop said:
"STM" and similar electromagnetic linear drives are better suited for mirrorless/on-sensor PDAF systems. Just check Rogers list ... https://www.lensrentals.com/blog/2016/04/a-look-at-electromagnetic-focusing/

Sony, Fuji, Zeiss (Batis) - all using a lot of Linear Electromagnetic AF drives, not only for low-end consumer lenses but also for big, "hi-end" lenses like Sony GM or Zeiss Batis.

Dual, triple, quad Linear Electromagnetic AF drives rulez for mirrorless operation. I would not be surprised, if Canon "EF-X" lenses will also be equipped with LEM AF drives, especially the "L class" ones. In combination with future, improved implementations of Canon DP-AF or Quad-Pixel AF it is something to look forward to.
STM and LEM AF motors are not similar (or if you prefer to believe they are, then USM motors are equally 'similar'). STM lenses are a tiny fraction of Roger's list, so that list does nothing to support the claim that STM lenses are 'optimized for mirrorless'. The fact that Canon uses STM lenses across the lineup —in EF, EF-S and EF-M lenses— also argues against that claim.

It may be true that LEM motors are optimized for mirrorless. But it could just as easily be due to the fact that mirrorless manufacturers have chosen to adopt that technology for cost or other reasons. Nevertheless, LEM motors were not part of the original claim. Moving the goalposts is a regrettably common tactic for those who's arguments are failing.
 

neuroanatomist

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Jul 21, 2010
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Re: A Bit More About the New

ethanz said:
While I've never used an STM lens, I don't think I've had any problems with my USM L lenses in live view.
Nor have I, not on DSLRs nor adapted to the EOS M/M2/M6. From what I've seen in this thread, one person has had a problem with one adapted lens, and another had no problems with that same model of lens. Occam's Razor suggests it's a defective lens, but here that somehow becomes lens incompatiblity and adapter problems.
 

fullstop

EOS 6D MK II
Apr 23, 2018
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Re: A Bit More About the New \

neuroanatomist said:
STM and LEM AF motors are not similar (or if you prefer to believe they are, then USM motors are equally 'similar').
I have to disagree. "STM" implementation/s by Canon are all using LINEAR motors, just like all LEM designs do. USM on the other hand always use rotational "drives".

Let me state my observation more precisely: i hold "LINEAR" drives [ideally with min. 2 "guiding rods"] for generally better suited in combination with [any sort of] on-sensor AF than ROTATIONAL drives. Especially for lenses that are focus-by-wire, without mechanical manual focusing coupling/gear.

And I also hold "drive energy to come from a electro-magnetic vocal coil or a piezo-electric element" better than yesteryears ultra-sonic, vibrating rings.

But ... personal belief, I am no engineer. Just an observant user. :)
 

Kit.

EOS 6D MK II
Apr 25, 2011
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Re: A Bit More About the New \

fullstop said:
I have to disagree. "STM" implementation/s by Canon are all using LINEAR motors,
According to their pictures, no, they are not. They are regular ("rotational") stepper motors.

fullstop said:
And I also hold "drive energy to come from a electro-magnetic vocal coil or a piezo-electric element" better than yesteryears ultra-sonic, vibrating rings.

But ... personal belief, I am no engineer. Just an observant user. :)
So, you don't realize that "ultra-sonic, vibrating rings" are a "a piezo-electric element"?
 

fullstop

EOS 6D MK II
Apr 23, 2018
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Re: A Bit More About the New \

No, i don't think "ultrasonic" and "piezo-electric" are the same thing.
Piezo-electric lighters for example don't say anything like "ultrasonic" [Canon], "super-sonic" [Sony], "hyper-sonic" [Sigma] on them. No "sonic" anything.

And if Canon STM really are "rotational", that drive mode will disappear too. Why on earth should a purely linear motion [move AF group/s forward or backward along optical axis] be driven by a rotational drive that needs some form of gear and/or "helicoid grooves" to convert its motion to linear? Probably owned to "manual focus" property on EF lenses.

Looking forward to reduced to the max, *pure AF* lenses. No rotation, no sonic, no gear, no focus ring, no moving mech iris blades, no mono-functional aperture rings. I would like to have a multi-functional ring around mount base on camera though. As implemented on a few Canon [and other makers'] cameras. :)
 

Kit.

EOS 6D MK II
Apr 25, 2011
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Re: A Bit More About the New \

fullstop said:
No, i don't think "ultrasonic" and "piezo-electric" are the same thing.
"Ultrasonic" is frequency. "Piezoelectric" is an effect that is used to convert electricity at this (or other) frequency into motion (or vice versa).

Are you really so ignorant of basic physics? That would explain a lot of your confusion.

fullstop said:
And if Canon STM really are "rotational", that drive mode will disappear too. Why on earth should a purely linear motion [move AF group/s forward or backward along optical axis] be driven by a rotational drive that needs some form of gear and/or "helicoid grooves" to convert its motion to linear?
Why not? It is proven to be a cheap and reliable solution.

fullstop said:
Probably owned to "manual focus" property on EF lenses.
No, STM lenses are focus-by-wire.
 
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fullstop

EOS 6D MK II
Apr 23, 2018
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Re: A Bit More About the New \

i know that canon stm lenses are focus by wire. even less reason to not using a LINEAR electromagnetic AF drive. :)

re. piezo vs ultrasonic ... confusion is on your end. those are 2 different things, as i said. never saw anything saying canon usm lenses using piezo-electric drive. if so, canon would pobably have called them "PEM" lenses rather than USM ... ;D
 

neuroanatomist

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Jul 21, 2010
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Re: A Bit More About the New \

Kit. said:
fullstop said:
No, i don't think "ultrasonic" and "piezo-electric" are the same thing.
"Ultrasonic" is frequency. "Piezoelectric" is an effect that is used to convert electricity at this (or other) frequency into motion (or vice versa).

Are you really so ignorant of basic physics? That would explain a lot of your confusion.
Yes, he is.


fullstop said:
re. piezo vs ultrasonic ... confusion is on your end. those are 2 different things, as i said. never saw anything saying canon usm lenses using piezo-electric drive. if so, canon would pobably have called them "PEM" lenses rather than USM ... ;D
And in your world, if you've never seen it then you believe it doesn't exist? No, that's not right...you seem to believe all the 'facts' you invent in your head.

[quote author=Canon]
The ring-type USM is actually very simple in operation. It is composed of a rotor and a stator – an elastic body with a piezo-electric ceramic voltage element attached to it. By applying an A/C current with a resonant frequency around 30,000Hz to the stator, vibrations are created causing the rotor to rotate continuously. 30,000Hz is in the ultrasonic range, and this is where the USM motors derive their name. (source)
[/quote]

Now, who's confused?
 
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fullstop

EOS 6D MK II
Apr 23, 2018
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Re: A Bit More About the New \

aha! alright. Canon USM is also piezo electric. Thanks for the information. 8)

That said, I'd still prefer LINEAR, gear-less, helicoid-free AF drives. :)
 

nchoh

EOS RP
Apr 3, 2018
208
113
Calgary
Re: A Bit More About the New \

fullstop said:
aha! alright. Canon USM is also piezo electric. Thanks for the information. 8)

That said, I'd still prefer LINEAR, gear-less, helicoid-free AF drives. :)
Good news for you, Canon has 2 versions of the STM motor. One is a gear-less and helicoid-free!
 

Kit.

EOS 6D MK II
Apr 25, 2011
1,403
782
Re: A Bit More About the New \

nchoh said:
fullstop said:
aha! alright. Canon USM is also piezo electric. Thanks for the information. 8)

That said, I'd still prefer LINEAR, gear-less, helicoid-free AF drives. :)
Good news for you, Canon has 2 versions of the STM motor. One is a gear-less and helicoid-free!
Actually, it is still "rotational" and comes with its own "lead-screw" helicoid.