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Jiri Vrozina
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I'm considering getting a few of these for night timelapses and general dark filming. The Canon or Sigma alternatives just cannot compare visually. Well the Sigma 135 1.8 is the exception and is very good.
Andreas
Phil, just wondering about the Otus lenses. We need some high quality primes. How good is the focus if you use remote control say RT Motion? We were recommended Cooke Mini for gimbal, but I mist say I like with the Otus that they are 1.4 instead of T2.9. Means you also got kick as low light lenses.
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.
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.
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.
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?