Thread: New Zeiss Otus??

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  1. #71  
    Phil- I have a tech question you might be able to answer. A question sparked by my having to decide between the Otus ZE and Otus ZF:

    Why is it that electronic-iris lenses such as the Canon EF glass cannot easily be made to have infinitely variable iris? Is it a mechanical issue?

    I've noticed that the re-housed EF glass from Cinematics and others where they add an iris is only done to the first version of the Canon 70-200mm, the non-IS version, and never to my knowledge to the EF 70-200mm f/2.8L IS II USM. And getting back to the Otus line, what makes it impossible, or too expensive, to convert the iris on the ZE Otus to being infinitely variable? Duclos doesn't perform that mod. And I don't know of anyone who does. Or if it even possible.

    I guess I am asking: What makes a stepped iris stepped? And why can't the motor move the iris in a manner that is not stepped?
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  2. #72  
    Moderator Phil Holland's Avatar
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    Quote Originally Posted by John David Pope View Post
    Why is it that electronic-iris lenses such as the Canon EF glass cannot easily be made to have infinitely variable iris? Is it a mechanical issue?
    More or less that's correct. The electronic iris doesn't have any sort of physical mechanism or exterior interface. So for a rehouse or mod job to do it you'd need to create one, which actually has been done in the past, but likely too much moolah for many when it comes down to it.

    The ZF mount already has a manual iris mechanism built in, so no biggie.

    I personally don't mind an electronic iris as long as whatever you're shooting with supports it. I ramp iris so rarely that it's never been an issue for me. Often though you're making the bigger choice of the focus pull going the right way or the wrong way when going with Canon or Nikon mount stuff. You can get reversing gears and even some advanced rehousing work on Nikon glass remedies it. But if my choice is between a mechanical iris and backwards focus and an electronic iris with correct directional rotation, well I pull focus everyday. I ramp the iris maybe once every 5 years.
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  3. #73  
    Quote Originally Posted by Phil Holland View Post
    More or less that's correct. The electronic iris doesn't have any sort of physical mechanism or exterior interface.

    Okay, but something physically moves the iris leaves, right? Why cannot that something be made to move the iris leaves in a manner other than stepped? Why can it only move from point A to point B and nothing in between? Why can't it be infinitely variable?

    I've searched online for the answer to this but not found it.
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  4. #74  
    Moderator Phil Holland's Avatar
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    Quote Originally Posted by John David Pope View Post
    Okay, but something physically moves the iris leaves, right? Why cannot that something be made to move the iris leaves in a manner other than stepped? Why can it only move from point A to point B and nothing in between? Why can't it be infinitely variable?

    I've searched online for the answer to this but not found it.
    Depends on the Iris Design. Part of the Duclos Cine-Mod for instance on physically adjustable lenses is to remove the stepped aperture adjustments so you can indeed have a smooth iris functionality. This is commonly known as "declicking". When you're discussing the electronic iris RED's integration of it allows for up to 0.1 stop increments. I've seen some fairly smooth stepless auto-iris in some exposure modes on cameras. Really depends on how anybody is tapping into that and if the iris motors can indeed be made to be smooth.

    On traditional cameras you typically have within the menu for still lenses support for 1/4 stop or 1/3 stop adjustments.


    We're in an interesting era at the moment where still lenses evolved to where they are and a new growing market of motion pictures lenses has evolved and will continue to do so. I suspect we'll see a bit more of a mingling of still and motion features in some lenses moving forward, as can be seen by the new electronic focusing mechanism deployed in the newest RF glass.

    As image makers we're inspired by lenses of all sorts. I know I've gone to rather extreme lengths to use lenses on film and digital motion picture cameras that were never intended for motion picture use and vice versa. I am certainly not the first to do so looking back into history. Much of the journey of image making optics has been how they've been optimized for their intended use. Lenses didn't have focus gears originally for instance and that's an expected feature on a cinema lens really.

    Somewhere in the next 5-8 years we'll see something pretty radical I'm sure. I've seen some guano crazy optical related stuff that hasn't touched our industry yet largely due to expense and practicalities.
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  5. #75  
    Quote Originally Posted by Phil Holland View Post
    Depends on the Iris Design. Part of the Duclos Cine-Mod for instance on physically adjustable lenses is to remove the stepped aperture adjustments so you can indeed have a smooth iris functionality. This is commonly known as "declicking". When you're discussing the electronic iris RED's integration of it allows for up to 0.1 stop increments. I've seen some fairly smooth stepless auto-iris in some exposure modes on cameras. Really depends on how anybody is tapping into that and if the iris motors can indeed be made to be smooth.

    On traditional cameras you typically have within the menu for still lenses support for 1/4 stop or 1/3 stop adjustments.


    We're in an interesting era at the moment where still lenses evolved to where they are and a new growing market of motion pictures lenses has evolved and will continue to do so. I suspect we'll see a bit more of a mingling of still and motion features in some lenses moving forward, as can be seen by the new electronic focusing mechanism deployed in the newest RF glass.

    As image makers we're inspired by lenses of all sorts. I know I've gone to rather extreme lengths to use lenses on film and digital motion picture cameras that were never intended for motion picture use and vice versa. I am certainly not the first to do so looking back into history. Much of the journey of image making optics has been how they've been optimized for their intended use. Lenses didn't have focus gears originally for instance and that's an expected feature on a cinema lens really.

    Somewhere in the next 5-8 years we'll see something pretty radical I'm sure. I've seen some guano crazy optical related stuff that hasn't touched our industry yet largely due to expense and practicalities.

    Maybe I am not being clear in my inquiry.

    "When you're discussing the electronic iris RED's integration of it allows for up to 0.1 stop increments. "

    WHY any increments at all?

    The motor of a Canon EF lens only moves the iris in steps. I get why that was the design. What I don't understand is why that motor can ONLY move the iris in steps. Does it use some sort of cogged movement mechanism, like in a clock, and that is why it cannot move the iris leaves distances within those "steps"?

    The iris motor moves the iris blades from position A to position B. Why can't it move the iris blades to a position halfway between position A and position B, or for that matter, to a position 1/10th or 1/50th from position A to position B?

    I'm wanting to understand the mechanism that produces stepped iris. And why it is that some lenses, EF lenses for instance, cannot be de-clicked so that the motor that moves the iris leaves is not restricted to the "clicked" positions but is instead infinitely variable, as when a manual-iris lens is de-clicked.

    What I am asking seems to be a question that few ask. They learn that some lenses can only operate the iris in steps but they never ask why that is.

    Even this Popular Mechanics article on Canon cameras and lenses fails to go into how it is that the aperture control is stepped. It mentions the aperture motors inside the lens, but that's it-

    https://books.google.com/books?id=y-...hanics&f=false


    My curiosity here reminds me of a time when I asked a traveling partner a question and he said to me in aggravated tone "There are just some questions you shouldn't ask. Okay? Why can't you just accept that it is the way it is and leave it at that? You think about sh!t you shouldn't think about and that's annoying".
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  6. #76  
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    Quote Originally Posted by John David Pope View Post
    the mechanism that produces stepped iris.
    Even more complicated. Depending on the electronic mechanism "some" Canon EF lenses can have "smooth iris" control, actually from what I recall very few. Most have a stepped mechanism however.

    Metabones if memory serves me right supports some lenses with smooth iris with a few adapters like EF to E. But again, only like 10 lenses across all manufacturers even allowed for it.

    Whatever the case, typically electronic iris is a low power electronic servo, which likely is why this isn't a "thing". Also since those lenses were mostly designed for still usage over the last 30 years, likely also why it's not a focus. But I would think for most manufacturers as of now it's likely a consideration.
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  7. #77  
    Quote Originally Posted by Phil Holland View Post
    Even more complicated. Depending on the electronic mechanism "some" Canon EF lenses can have "smooth iris" control, actually from what I recall very few. Most have a stepped mechanism however.

    Metabones if memory serves me right supports some lenses with smooth iris with a few adapters like EF to E. But again, only like 10 lenses across all manufacturers even allowed for it.

    Whatever the case, typically electronic iris is a low power electronic servo, which likely is why this isn't a "thing". Also since those lenses were mostly designed for still usage over the last 30 years, likely also why it's not a focus. But I would think for most manufacturers as of now it's likely a consideration.

    Maybe this gets us closer to an explanation? ( It is above my head, honestly )-

    "The lens/camera protocols of Canons and Nikons are somewhat similar at one level, but the philosophy of protocol design is completely different.

    Both systems use serial communication between camera and lens. There is a slightly different electrical configuration, Canon uses separate unidirectional data lines lens-to-camera and camera-to-lens, while Nikon use a bidirectional line with a separate signal saying which direction the data is travelling. Whatever, they both use essentially three signals to communicate serially between the lens and camera. The protocol design however is differently conceived. Canon's protocol involves the camera issuing commands and the lens responding with information or action, in a number of different response formats. One of the first commands requests the protocol version, and the camera/lens negotiate upward through protocol revisions (why the performance keeps on improving but the system is still compatible with the earliest EOS lenses) there have, I think, been four versions of the protocol so far. The commands include moving focus and aperture."



    I'm still not understanding just what it is that makes the iris stepped and stepped only. Software? The nature of the electronics involved? Or is it something physical, something like the cogged action of clock gears?

    A motor moves the iris blades via a mechanism. But it can only move the iris blades in steps. And for some reason it cannot be altered to move the iris blades in anything but stepped progression. Not easily, at least. Or someone would have done it and made a ton of money selling the service.

    Apparently it isn't that it is cost prohibitive. I am not aware of it ever having been done at all. Not even on a single example of the lenses. Not even as a very expensive one-off.

    Thanks for the exchange, Phil. I'm not sure if I got my answer but I did learn something and enjoyed the conversation. Maybe I just need to accept that it is how it is and not try to understand why it is how it is.


    Edit: What I find interesting is that on the versions of the Canon 70-200mm that have been "cinevised" by re-housing and adding a manual iris ring, the direction of the ring is "backwards" from that of dedicated cinema lenses. Apparently there was some hurdle the re-housers could not easily or economically get around to make the iris modification operate the same rotational direction as with true "cinema" lenses.

    Last edited by John David Pope; 10-17-2019 at 12:41 AM.
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  8. #78  
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    So Phil...is new Otus lenses this year ?.
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  9. #79  
    Senior Member Patrick Tresch's Avatar
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    Isn't the stepped iris design due to common photographic use and culture : to have solid stops and 1/3 stops and not strange numbers like F6.7 or F10.2?
    It could also be due to an easyer design than continuous electronic and mechanism desing?

    I love to grab the lens with my right hand and rock that iris manually during the shot if needed.
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  10. #80  
    Quote Originally Posted by Patrick Tresch View Post
    Isn't the stepped iris design due to common photographic use and culture : to have solid stops and 1/3 stops and not strange numbers like F6.7 or F10.2?
    That goes to the why of the design but not to the why the design cannot be modified.

    I get why Canon made it that way. What I don't understand is why that stepped design cannot be modified to be stepless. I don't understand what it is that limits the motor / mechanism to jumping to another position, why the movement cannot be feathered without those "jumps" to a new positioning.

    On a related note, Canon has said that they will offer their new RF lenses in a factory modded form that eliminates the clicks from the control ring. What is not yet clear is if that will make for seamless adjustment of the iris / aperture-

    https://www.newsshooter.com/2019/05/...-on-rf-lenses/

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