...But does electronically stepped always mean that the iris steps will always be huge and noticeable?
i.e. How small does a F-Stop change have to be before it appears continuous ?
Smooth Iris
- Thread starter Jim Simon
- Start date
...But does electronically stepped always mean that the iris steps will always be huge and noticeable?
i.e. How small does a F-Stop change have to be before it appears continuous ?
stoneinapond
Veteran
This lens steps in one third stops. Each step is quite noticable and the lens makes a click with each step. Even with declicked manual lenses, exposure changes can be easily seen if not done with care, but they will appear smooth as opossed to stepped.
I don't know if any cameras feature one quater stops. But even if any did, I would hazard a guess that such steps would also be apparent.
So is this a camera limitation?
In other words a lens's electronic aperture might be capable of changes in 1/10th of a F-Stop increments, but if the camera controls don't enable this type of precision we are stuck with whatever the camera interface allows.
M. Gilden
Canon DSLR Moderator
Ok, let's explain a few things because I feel like we might not all be on the same page here. Aperture blades move to create a smaller or larger pinhole of light through the lens. On an manual aperture lens (such as anything vintage), "clicks" are put into the ring in order to allow the user to stop it at a precise f-stop measure. Otherwise, while adjusting the aperture ring on something like an F/1.4, the difference between 2 and 2.8 is almost impossible to tell without the the click into place. Lenses can be "declicked" if desired by simply removing the bearings or whatever is there to make the ring stop at each increment.
With electronic aperture, this doesn't really work the same way. There are no physical "clicks", rather the aperture blades are attached to a tiny motor that adjusts the size of the iris as needed. The camera can either adjust them automatically (for example, if the dial is in full-auto or shutter priority, etc), or you can dial it in manually (dial in M, Av, etc). Here's the difference- when the camera adjusts automatically, say from being outdoors at F/8 to indoors at F/2.8, the camera tells the lens motor to move into the new iris position. You will see it adjust, but it should do so rather smoothly. When you dial it in manually, you will see it jump in increments as you adjust the wheel (not to mention whatever fumbling with the camera will be visible as you navigate the UI to adjust that). Whatever size those increments are, I'm not sure if they are dictated by the camera or the lens, but they are pretty much stuck at whatever they are unless you manage to hack and change some of the code that controls that (to my knowledge, this is mostly impossible unless you are a Panasonic engineer). I'm not sure why you would even want to adjust aperture while shooting, the ergonomics to do that electronically on-the-go with a camera this small are a nightmare. That's the advantage of a having a fully manual lens (focus and all) that is de-clicked. Or use an adapter with a ring (those override the lens' own ring, and therefore can change iris size without clicks).
It really all comes down to- what on earth are you trying to shoot with fully automatic lenses that would require you to also want "declicked" electronic aperture?
As someone else already mentioned in the thread, this sounds a lot more like a job for an ENG videocamera than a DSLR.
...But the tiny motor that moves the aperture blades has an electronic index where the camera tells the lens to set itself to a specific "index" that equates to a specific F-Stop for every electronic lens that is attached to the camera body.
So say the camera tells the lens to go to "index 800" which might be equivalent to f/4.0 for every electronic lens that is attached to the camera body. To stop down to f/5.0 ( 2/3 stop down from f/4.0 ) the camera might tell the lens to set itself to "index 1000", but what if the camera could tell the lens to set itself to "index 820" which might be equivalent to f/4.1.
I know that the AF focusing motor and aperture control motor built in to the Canon USM lenses function this way, with something like 4,000 increments between infinity focus and the closest focusing distance. ( no idea how many increments there are for the aperture motor ) The Birger EF lens adapter demo showed that users could select F-Stops in 0.1 of a stop increments.
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M. Gilden
Canon DSLR Moderator
Yes, I mentioned that:
"Whatever size those increments are, I'm not sure if they are dictated by the camera or the lens, but they are pretty much stuck at whatever they are unless you manage to hack and change some of the code that controls that (to my knowledge, this is mostly impossible unless you are a Panasonic engineer). "
The point is that the camera can smoothly adjust aperture if you are using automatic iris control (because it is not a physical limitation), but you can't dial in positions that the software won't allow. They question is, what is the OP trying to do exactly? Personally, the reason I wanted to have a particular lens declicked is because I wanted to be able to adjust the ring for varying light during a documentary shoot. I suppose its always possible that someone out there is saying "Hey, F/4 is ruining my shot- I really wish I could get F/4.1!", but I somehow doubt that happens often. I really hope the OP isn't expecting to be able to smoothly adjust the iris electronically while shooting.
My understanding is that the camera ( or external controller like a Birger adapter ) sends focus and aperture commands to the lens, and the lens does whatever it's told to do. In the Birger RED camera demo, they show that their remote controller dial can be manually adjusted in increments as small as 0.1 of a F-Stop while shooting, and that this adjustment is pretty much fluid, so you can twist the controller knob to slowly open or close the aperture while shooting. This is with Canon EF USM lenses, but I would expect high quality M4/3 lenses to behave the same way.
I think this works identically in full manual mode, where the camera or controller keeps sending new focus/aperture settings to the lens and the lens does whatever it's been told to do. The only issue I've heard of is that many lenses don't have motors that are designed for continuous adjustments ( i.e. auto-focus / auto-aperture ) so they either won't work well or you run the risk of burning out the lens motor.
M. Gilden
Canon DSLR Moderator
That's what I figured, but I was wondering if the precise locations of each F-stop formation are coded into the lens to communicate with the camera body. Meaning, the lens has to communicate with the camera to determine what the aperture rating is wide-open. I assume that the blade motor will adjust it to whatever position the body determines, but how does the body know what positions are available? Is it mathmatically calculated based on the size at wide-open, or is there an array of possible values that the lens feeds the body electronically along with the other lens information?
What I'm trying to say is that perhaps some lenses will allow the body to adjust in smaller increments versus others. The birger demonstration does not prove whether or not this is true.
That assumes that we would have some sort of external control or knob to adjust it as smoothly as the birger did. If so, I would imagine it would be pretty smooth. But we don't. Here in Micro 4/3rds land, we have small cameras with difficult to navigate ergonomics and a sticky scroll wheel to adjust aperture (when in the right mode to do so). Even if a Panasonic engineer or hack were available to make smaller adjustments, I still am not convinced it would be smooth during recording unless there is a remote or some other way to adjust it. If you want micro adjustments for exposure of DOF, that's another story. Either way, the OPs request to have the lens "de-clicked" doesn't seem applicable.
gonzo_entertainment
Veteran
Typically used in a camera move between different lighting conditions. Say you started inside and then followed the talent out onto his front steps. There is no way the same aperture would work for both lighting conditions. The answer is to do an aperture pull as the lighting changes.
The answer to OP's issue is either a cinema lens or a de-clicked lens where the iris is mechanical not electronic.
Thank you very much Gonzo for the hints :beer:
Would it be not possible to use an ND Fader to adjust the lighning conditions like I wrote before ? One of my lens is a modern Nikkor lens with electronics, but I use it sometimes with an adapter and you can change the iris manual and smoothless with it, fine tuning can be a task maybe for such an iris pull. Never tried this.
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Shooting events? Yes quite often.
Like I said, you get no control over the scene, lighting, subject matter, etc. You have 2, maybe 3 seconds to frame the shot, expose the shot, focus the shot and start recording or you lose that shot forever.
And sometimes, you don't even get that 2 seconds.
Wait a minute. These lenses don't come with an Iris ring?
Not electronically, mechanically. I want both full auto and full manual (via lens ring), like any standard video lens has.
M. Gilden
Canon DSLR Moderator
The OP is referring to a native Lumix lens. Lenses like the 14-140 have no iris ring. Heck, even the focus is by-wire, but at least it doesn't require using a scroll wheel to adjust.
Yes. Know of a zoom for the GH2 costing less than the camera body?
Well, that one's off the table.
Do any of the m4/3 zoom lenses for the GH2 have a proper iris ring?