An interesting property of the diaphragm on the Nikon CZK

When writing an article 'Aperture and video on the Nikon CZK'I encountered unusual aperture behavior on different lenses with different cameras. Below I will describe my experience, but I ask readers to send in their conjectures and observations, indicating the camera and lens in the comments to this post.

Nikon camera diaphragm closure

Aperture on Nikon cameras

Bunch Nikon D80 / Nikon D5300 with lens Nikon DX AF-S Nikkor 35mm 1: 1.8G SWM Aspherical:

If you shoot at a fully open aperture (F / 1.8 for this lens), you can see how after the end exposure aperture blades instantly close and open. Presumably, the petals should not move at all, since the shooting takes place on a fully open hole. Petals close very tightly, but not completely. Exactly the same effect is observed in Nikon D80 when using the diaphragm repeater function.

The question is for what? And why there is no such effect on other cameras. And also why Nikon D5300 when turned on and off, Live View works more predictably - it only closes the aperture to the specified value and reopens it when exiting Live View.

Here is a visual demonstration on Nikon D80:

 

Here link to the original video с Nikon D80 and 35 / 1.8G + link to the original video Nikon D80 and Nikon AF Nikkor 35-70mm 1: 3.3-4.5 + link to the original video с Nikon D5300 and 35 / 1.8G + link to the original video с Nikon D5300 and Nikon AF Nikkor 35-70mm 1: 3.3-4.5. You can watch more interesting videos on my youtube channel.

Bunch Nikon D700 with lens Nikon DX AF-S Nikkor 35mm 1: 1.8G SWM Aspherical:

  • If you shoot at a fully open aperture (F / 1.8 for this lens), then no closing / opening of the aperture occurs (presumably this should be).
  • If you shoot with a closed aperture (F / 2.0 and F / 2.2 are used in the video), then the aperture blades first close to the set value, after which they close much stronger (presumably not completely) and open again.
  • If you shoot at a completely closed aperture (the video shows F / 22), it is noticeable that the petals are closed completely.

Exactly the same effect is observed when using the aperture repeater function and when turning on / off the Live View.

Here is a visual demonstration on Nikon D700:

Here link to the original video с Nikon D700 and 35 / 1.8G. It’s difficult for me to make a video for others with a lens, because the aperture is set deep there and it is visually difficult to shoot it on video.

With the same cameras, the rest of the lenses that are at my fingertips behave exactly the same way, namely:
Nikon DX AF-S Nikkor 18-200mm 1: 3.5-5.6GII ED SWM VR IF Aspherical, Nikon AF Nikkor 28-105mm 1: 3.5-4.5D, Nikon ED AF Nikkor 80-200mm 1: 2.8D and Nikon AF Nikkor 35-70mm 1: 3.3-4.5. While observing, I use the 'M' mode, but the same happens in the 'A' mode. Before starting monitoring, I reset the cameras to factory settings.

I don’t think the cameras have any problems, as Nikon D5300 I got a review completely new, and Nikon D80 и D700 Recently been on the diagnosis. Also, I do not think that the problems are in the lenses, since different types and models of lenses (D, G, AF, NON-D, NON-G) behave the same on the same camera.

Unsubscribe in the comments. Thanks for attention. Arkady Shapoval.

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Comments: 78, on the topic: An interesting property of the diaphragm on the Nikon TsZK

  • Sergei 02

    Nikon D600 + 35-70 2.8D With f2.8, you don’t see any aperture closing, it’s worth starting to squeeze, the effect immediately begins to be observed, as described in the article, the more you cover, the more it starts to cover up when shooting.

    • Dmitry Nosov

      Sergey 02, hello. Even you misunderstood.
      “The more you cover up, the more you start to cover up” - this is clear.
      Interested in the behavior of the diaphragm after the exposure.
      Do you have an instantaneous closure of the aperture from the set value, presumably not to the end, and instantly open immediately after the end of the exposure?

      • Dmitry Nosov

        Do you have, after the end of the exposure, an instantaneous closing of the diaphragm from the set value, presumably not to the end, and there is an instant opening there?
        Oh, that's better ...

      • Sergei 02

        I mean 2.8 stands still during the exposure, then on the remaining numbers f there is an instantaneous closure of the diaphragm not until the end, and then there is a moment. opening after the end of the exposure.

  • Dmitry Nosov

    Instant darkening in the OVI is clearly visible after releasing the depth-of-field preview button (jumping from the set value to closing and back) ...

  • DimDimych

    I will try to assume that this behavior of the aperture jumper is connected only with the mechanical implementation in the camera itself, which is in no way connected with the lens. Maybe on cameras where this effect is observed, the cam pushing the camera's jump lever pushes it not completely, but to the position of the desired aperture, then the shutters open, then it turns, pushing the aperture to the maximum and returning to the starting position for the next shot? And on cameras where the effect is absent, the device of the jumper lever is different.

    • Felix

      I think everything is much simpler, in the footsteps a blade is installed to which the diaphragm pusher reaches, then a frame is made, the blade is removed, the spring is brought in, and everything is returned by the motor with the bolt spring.

  • Nikita

    d3200 + 35 1.8g on the open twitches 1-1.5 mm at the time of shooting.
    Another interesting point ... the fast stone program gives out in the properties of photos on the open 1.74 and not 1.8 (maybe the twitching of the diaphragms and there is compensation for fixing f1.8 ...)

  • Sergei

    Nikon D5200 Nikkor AF-S 35 \ 1.8G - I didn't seem to find extra movements ...

  • Skai

    d610 + 24-70 - no movement is observed when shooting at any aperture.
    35 1.8 dx also on any diaphragms is covered up to the installed one and that’s it. (In open traffic not observed)

  • Jury

    I checked it on c5pro and 85 1.8AF - everything is fine, there are no unnecessary movements, both when shooting and when viewing the depth of field. There is no movement on a completely open one. To find out the truth, you need a kit with unnecessary movements and a kit without those in one hand :).

  • travel

    I will express my assumption not related to the above. I once came across a description of such an algorithm for additional noise reduction at high ISO / long exposures on cameras that have only an electronic shutter. After the shot, the camera, not having a full-fledged shutter, covered the aperture as much as possible, subtracting a few “dark” signals from the shot. It looked exactly like what Arkady describes. There could also be a situation when on the open one - just a snapshot, and on a slightly covered one (the camera decides that it is already dark and it's time to apply the "feature") - first it is covered up to the desired value and then completely for a short period of time.
    I don’t know how this could sneak into this camera (if it is at all), maybe some firmware versions are glitches, but the behavior is similar.

  • Alexander

    D200 + 35 1.8G there are some twitches described above. At f / 2, it closes to ~ 2,8.
    Paired with the Nikkor-Q 135 f / 2.8 is not noticed.

    IMHO, Arkady himself answered)
    / If we use a lens with a microprocessor, the camera knows how much to lower the "pusher" so that the aperture closes to the desired value (the value is set via the camera menu). If we use a manual lens (without a microprocessor), then the camera lowers the "pusher" to the stop. In this case, the aperture value is controlled using the aperture ring, which allows the aperture blades to close only to the set value (but not more) ./

    Twitching may be related to the operation of the mechanism.
    The actuator opens the diaphragm by means of a spring (when the lever is at the top).
    Closes the same downward movement. Therefore, it is possible that when the lens is already throwing the aperture from a given value, the camera (read - the mechanism by means of a spring) does not have time to pick it up at the required speed (the inertia of the petal drive and lever drive can be recognized in Japan, Tokyo, Nikon headquarters :)
    Therefore, the feature = camera + specific lens (usually not manual).
    At the expense of covering even on the open one - maybe this 1.8 is not 1.8)) I've seen exif with a higher aperture many times.
    All assumptions IMHO. How everything actually happens - only the manufacturer knows.
    Without a lens, the camera always opens completely. Therefore, you need to check with dandelions, for example)) Or the leash of the diaphragm, which did not achieve a special result.

    • Alexander

      I am 99.9% sure that the camera pushes the lever ALWAYS at the maximum value, or rather tries to push as far as the lever allows, then the aperture is limited in the lens drive itself. The described situation on some cameras is due to the fact that the algorithm of work is (IMHO):
      1. The value of the set aperture is transmitted to the lens.
      2. The lens sets the diaphragm drive in such a way that it closes only to the set value (on mechanical lenses there is a physical restriction on the degree of closing of the diaphragm when we twist the ring, the limiting drive must be on the processor lenses in the lens itself).
      3. The diaphragm pusher in the camera fires to CLOSE the diaphragm.
      4. Further, the lens is transmitted that the frame is shot, the restriction can be removed. And rather, at the same time, the camera returns the pusher back, but due to the design of the camera and the apparently slow drive of the diaphragm, it manages to close.

      The movement of the pusher is very small and it was problematic to accurately dose the diaphragm, because Communication is most likely not linear on different lenses. You can check by disassembling the lens and see if there are any electronics and drives at the diaphragm.

      • Jury

        Alexander, all of the above-described Nikon lenses do not have electronics in the diaphragm drive - an exceptional mechanics, for many decades. The drive is only in the new https://radojuva.com.ua/2014/05/nikon-e/ series, which was not discussed here.

  • Alexander

    I asked a friend of the master.
    The impact diaphragm has a principle similar to the operation of an automatic weapon mechanism.
    Beat, reload, hit again.
    At the time of reloading, when the mechanism returns to its original position, you can observe the covering of the diaphragm. Then the lever cocked, shoots to the desired value, which is limited by the electromagnet in the lever drive on the camera itself. The desired value for the lever position is set by the encoder (a kind of optical lever position sensor). Then the cycle repeats.
    There is no aperture control in the lens, as The jump rope was invented even before these microprocessor lenses of yours. A purely mechanical solution.
    Hi backward compatibility.
    Nikon, in turn, is sawing the entire diaphragm solenoid so that she can keep up with the modern shutter speeds.
    Hope the secret is revealed.

    In theory, it would be necessary to test more various lenses.

    • Dmitriy

      In any video showing Nikon's "rate of fire", you can see how the "pedal" on the carcass is lowered synchronously, for each frame, so there is no recharge

  • Alexander

    so optics: sigma 24-70HSM, nikkor 50 / 1.8D, 18-35D, 24-70 (not vr) - I haven't seen this on all these glasses on d200, now I don't see this either with d700 (mileage 180 thousand, if that's a question wear)

  • Peter Sh.

    Jumping aperture is a certain way in some Nikon models to cope with inaccurate calculation of exposure. The diaphragm closes to the maximum and one stop lighter. So it seems that it is jumping. The engineers came up with this after user complaints.

  • Alexander

    This is a bunch of new programmers who have forgotten why cameras have a jumping aperture.
    The same jamb has been with SONY-A series cameras for 6 years now.
    In the latest versions of the A7R-IV and A9, they finally added an “AF priority” item in the aperture drive settings, but only in AF tracking mode and this does not work with all lenses.
    The reason for this is due to the specifics of AF operation in modern cameras, the so-called “shift focus”, which causes a shift in focus when closing and opening the aperture.
    Although I personally have never noticed anything like this.
    But there was a lot of howling about this on the Internet.
    Mostly from hand-assed photographers))

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