Cinema cameras are also very rarely used very close to an omnidirectional microphone—a slightly audible fan would not be picked up by the external lav and shotg

Cinema cameras are also very rarely used very close to an omnidirectional microphone—a slightly audible fan would not be picked up by the external lav and shotgun mics recording the talent / action. Some people recording with the R5 or other more compact systems might rely on internal mics or a shotgun mounted atop the camera for audio, and that definitely picks up sound emanating from the body, at least a little. Many lenses' focus motors are loud enough to be annoying in onboard video.