The relative aperture ratio of the camera’s simulated lens.
- iOS 9.0+
- macOS 10.11+
- tvOS 9.0+
- Model I/O
Relative aperture, also called f-stop or f-number, is a measure of the amount of light permitted through a lens to an imaging surface, commonly thought of as the “speed” of the lens. The f-stop is the ratio of the lens's
focal to the diameter of the entrance pupil. It controls the amount of light that reaches the sensor, as well as the size of out-of-focus parts of the image.
The default relative aperture is is
5, simulating an f/5.6 lens.