Rotating aperture drum on vintage film cameras — adjusts f-stops without lens change. Archaic but critical on 16mm classics.
You're shooting with an old Bolex or Arriflex 16, and suddenly you realize: the lens is stuck, it can't be changed. Instead, you find a cylinder with several apertures of different sizes on the front of the camera body — that's the tambour. It functions like a mechanical aperture dial that you turn in front of the lens to regulate the amount of light without removing the lens. In the analog era, it was a practical solution for cameras with fixed lenses, especially for 16mm productions and documentary shooting.
The tambour sits directly in front of the lens and carries four to six aperture openings — typically f/4, f/5.6, f/8, f/11. You turn the cylinder by hand or via a small gear until the desired aperture is in front of the light. This saves time when switching between exterior and interior shots and you don't have ND filters at hand. On set, this works reliably as long as the mechanism isn't rusted — and that's precisely the problem: many of these cameras have been stored for decades.
Practical Hurdles: The tambour is sensitive to dirt and wear. Sometimes the rotation gets stuck or jumps between settings. Moisture, dust, and old lubricants turn an elegant design detail into a nightmare. Before shooting, you should test the rotation and cycle through all positions — smoothly, without sticking, engaging precisely. If the tambour is defective, you usually need a service technician or have to resort to external aperture systems.
Today, cameras (as far as 16mm is still shot) work with iris rings or integrated aperture motors — more flexible, faster, cleaner. The tambour is classic equipment, belongs in every documentary about the history of camera technology, and is unavoidable when working with archival cameras. Those who are familiar with it have an advantage: it's pure mechanics, no electronics. If it works, it works reliably.