ISO 15781:2015 specifies how to measure and report the shooting time lag, shutter release time lag, shooting rate, and start-up time for digital still cameras including camera modules in phones and tablet computers. It includes a method that uses control signals inside the digital still camera and a method that determines the timing values without requiring access to the inside of the digital still camera.
Depending on the method used to start the timing device, there can be a time lag between the activation of the timing device and the closure of the exposure switch of the digital still camera.
This International Standard does not address the measurement of auto focus accuracy and speed at low light conditions.
For digital still cameras that continuously shoot images into the buffer, the exposure button only acts as a selector of an image that was taken before the exposure button was pressed. The methods to measure shutter time lag and shooting time lag do not address this case and cannot be used for this type of digital still camera.