Meter for monitoring camera speed — verifies actual frame rate during operation. Essential for slow-motion and high-speed work.
On set, you need a reliable instrument to ensure your camera is truly running at the set frame rate. The tachometer — known in German as the Schnellmesser or Drehzahlmesser — is precisely the tool for this. It is an analog or digital measuring device that monitors the actual rotational speed of the camera motor or film transport mechanism, showing you in real-time whether the frame rate is stable.
In practice, it works like this: you hold the device to the rotating camera shaft, a drive gear, or a marked disc that you attach to the camera specifically for this purpose. The tachometer captures the rotations and calculates revolutions per minute (rpm) or the corresponding frame rate. At 24 fps, you need to achieve a specific rotational speed — these values are standardized and vary depending on the camera type. Analog models work with a spindle that you press; digital variants use optical or magnetic sensors and are more precise.
The device becomes indispensable when shooting slow-motion or time-lapse. At 120 fps or higher, human perception can be deceiving — you can't tell if the camera is truly running as planned or if the motor is faltering. A voltage drop in the power supply, worn belts, or simply aging of the equipment can lead to deviations that become visible in the edit: jerky motion instead of smooth slow-motion footage. With the tachometer, you don't rely on hope. You measure. The same applies to hand-crank cameras — here, you need to regulate your cranking speed, and the tachometer immediately shows you if you are turning too fast or too slow.
Modern digital cameras with electronic control rarely need this device, as the camera regulates itself. However, for 16mm film cameras, specialty rigs, or older broadcast cameras, it is standard. Good grips and 1st ACs have one in their toolbox — along with spare batteries and the knowledge of when it's time to measure. A quick check before the first take will save you a lot of trouble in the DCP later.