I'm listening to a podcast with Nicholas Meyer so I'm in the mood to recount old stories.
They put markings on the buttons of the TOS set in Enterprise in 2005 because they thought the detail might be needed. When they played it back (in HD!) the markings vanished. So I thought: Maybe the markings were always there but we could never see them!
Try this: Instead of thinking of the glorious 35mm film that we've now gotten to see the same way Gene and the gang saw them in the Desilu screening room, think of them on a 25 inch color TV. Take your lusciously detailed vent, shrink the render down, mess it up, make it look like TV. Does it look the same as the original? BAM! It was ALWAYS a vent. We just didn't have the tech to see it!
Have fun!