For synchronization it would be best to have an external pulse to control both frame rate and exposure. You would still want to share a trigger signal. If you are just triggering both cameras at the same time - sharing a common trigger, you have no control over their clocks.
Think of the frame capture as the series of dashes in the lines below. Periods just represent time between frames. T= point in time trigger is received. If the recording ends at the trigger, it could look like this:
Cam-1 |...|...|...T
Cam-2 ...|...|...|T
The same number of frames (dashes) were captured. Just not "in-sync". How close in time the frame captures could be is dependent on frame rate. At 10,000fps two separate cameras sharing a common trigger would have frame captures within 0.0001 sec (1/10,000) from each other max. At 1,000fps that time would be longer, 0.0010 sec (1/1000) max. Obviously the faster your object's motion, the more critical the timing becomes.
When you utilize the Edge Triggered and Shutter Gating features, you are truly synchronizing the cameras, assuming cable lengths are the same to each camera. Tesla500 would best be able to define the timing resolution in that scenario.
