One thing I read a lot is that serious timelapse photographers use fully manual lens. The need to avoid auto-focus and hence focus changing undesirably during a sequence of images is obvious; however, the need for a manual aperture not so clear.
Most modern lenses use an electronic aperture or diaphragm. The aperture is wide open helping the camera auto-focus quickly. Then when the shutter (or depth of field button) is pressed the aperture is narrowed by electrical impulses from the camera to the lens.
How accurate and repeatable is aperture actuation from one shot to the next? …
Researcher / Photographer / Programmer