I'm using a Nikon D5300 with a Manual Nikkor 28mm F/3.5 lens.
I've been using this set up for years for stop-motion animation without a problem but recently noticed that when I rotate the camera's aperture ring (physically) it produces no change in aperture in the shots. I've removed the lens and changed the aperture while looking down into it, and the blades are physically moving. However, when I reattach the lens and take a few shots with the camera in Manual (but not hooked up to the laptop), the photos are all the same exposure.
I've tried looking for a setting within the camera that might have been accidentally changed, but can't find anything that works.
I'm not a natural with settings but have done a whole bunch of internet research with no success.