Video tachometer 2.1

When the frame rate of a video matches the speed of a specific part, it creates a strobe light effect, causing that part to freeze in the video.

Utilizing the adjustable frame rate of a video, this effect can be employed to determine the rotational speed of a part.

To make use of this feature, your smartphone must support slow-motion video recording at a high frame rate. This functionality is available on all iPhones starting from iPhone 5S. The frame rate ranges are as follows:

• 0.5—240 Hz (30—14400 RPM) for iPhone 6 and newer models.
• 0.5—120 Hz (30—7200 RPM) for iPhone 5S.

The value in Hertz (Hz) is more accurate than revolutions per minute (RPM), as RPM is calculated from Hertz and rounded accordingly.

To capture clear images, adequate lighting is essential. The image clarity is determined by the exposure settings of the video, including the exposure time and light sensitivity (ISO). Decreasing the exposure time enhances clarity but reduces brightness. Conversely, increasing the camera's light sensitivity (ISO) raises brightness, but also introduces more noise. Manual adjustment of the camera's focus is also necessary.

Videos can be recorded using the iOS "Screen Recording" function.

To capture a photo with the displayed measurement result, simply press the "Pause" button and take a screenshot.

It is possible to choose a video format that offers superior quality but has a significantly lower maximum frame rate. The difference between formats becomes noticeable primarily when using digital zoom and the Rolling Shutter effect may be more pronounced in higher quality formats. Therefore, it is recommended to use the highest quality format for speeds below approximately 1000 RPM.

Hints can be enabled to facilitate observation of changes in rotation speed. These hints provide guidance on adjusting the frame rate (increase or decrease) based on the direction of the rotational mark. Although hints need to be manually selected, they eliminate the need to remember this information. Hints are particularly useful for frequencies close to the rotation frequency and can be pre-selected if the rotation direction of the impeller is known. The arrow indicating the direction of rotation must correspond to the "+" button.

The video tachometer functions in the same way as a stroboscopic tachometer, accurately measuring rotational speed.