The time from when the register is written on the camera to when the start of integration occurs can only be approximated. The average time from register write request to register write response is approximately 49.85 us. The "register write success" response is only sent from the camera to the host system once the internal trigger pulse is initiated. We then add the trigger latency (time from the trigger pulse to the start of integration) to this, which is approximately 6us for a 640 x 480 camera (see the Related Article below).Therefore, the total time from when the register is written to the start of integration is approximately 56 us.

The important point to note is the above timing is solely from the camera perspective. It is virtually impossible to predict timing from the user perspective due to latencies in the processing of commands on the host PC (i.e., the time from the user hitting a keyboard key to initiate the register write, to the start of integration).