Why is it not possible to change Aperture in Livewiev on a Nikon D5300 when using manual movie settings?

Question

I've been using my Nikon D5300 for about 1.5 years and have recently started to use it for some video work aswell. I realized that when manual movie settings are turned on and you go to Liveview, you

1. Cannot change the shutter speed to every value - it must be faster than the number of frames per seconds; e.g. I cannot go below 1/30th when shooting in 24 fps. This makes sense to me and isn't a problem because I anyway use the 180 degree shutter rule (i.e. shutter speed = 1(2*fps) which is 1/50th for me).

2. Cannot change aperture at all. This is more of a problem, but can be solved by switching liveview off, changing the aperture and the go back to Liveview. I wonder why manual movie settings prevent you from changing aperture in Liveview?

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I considered posting this on Video SE but decided to ask here since 1. the D5300 ist primarily a photo camera and 2. The question is not directly about recording or editing video. If you anyway think it fits better on Video SE, please feel free to migrate the question or tell me so that I can repost it there.

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Update Here is some additional information:

• This "problem" occurs both with my 18-55mm Kit Lens (AF-P DX 3.5-5.6G VR) and my 35mm lens (AF-S 1.8G)

• Apparently, you cannot change Aperture at all in Liveview (at least in my Camera). However, I can change the Aperture value when manual movie settings are turned off - the number displayed changed and the photo will be taken at the aperture I set. This is not possible with manual movie settings - the aperture number just "freezes" and cannot be changed.

Answer 1

Because in the Nikon D3x00 and D5x00 series, as well as many previous entry level Nikon DSLRS and pretty much all Nikon 35mm film SLRs, the same mechanical motion actuates the mirror assembly and the aperture linkage. Once the mirror is up, the aperture can not be changed from the body. This worked fine when the mirror was always down until just before a photo was captured.

With the advent of Live View shooting, it's proved to be not quite as elegant a design.

If the aperture needs to be changed from what the camera is using for Live View, the mirror must cycle to change the aperture. Just one of several legacies from the pre-autofocus era that remained in Nikon AF film SLR bodies and digital SLRs for many generations of products in an attempt to keep all legacy F-mount lenses compatible with the newer cameras.

Only within the last half decade has Nikon started to adopt in earnest new ways of controlling the aperture electronically instead of mechanically. This has come at the cost of some newer bodies not being compatible with older F-mount legacy lenses. They straddled the fence for many years with their upper tier bodies by separating the mechanical actuators for the mirror from the actuators for the aperture, but continued to use the legacy design for the lower tier bodies such as the D3x00 and D5x00 series.

However, I can change the Aperture value when manual movie settings are turned off - the number displayed changed and the photo will be taken at the aperture I set. This is not possible with manual movie settings - the aperture number just "freezes" and cannot be changed.

This is because when you are taking still images in Live View Mode, the mirror cycles each time you take a photo. When you press the shutter button to take a photo, the shutter closes so the sensor can be cleared/reset, and the mirror cycles so the aperture can be set. Sometimes the cameras also needs to cycle the mirror to use the PDAF sensor, which depends on the secondary mirror attached to the partly semi-translucent main mirror to direct light to the PDAF array, in order to focus the camera.