You technically can measure over the nyquist frequency, for example here if you measure 80Hz with your 60Hz camera, you can be sure that either you really did t

You technically can measure over the nyquist frequency, for example here if you measure 80Hz with your 60Hz camera, you can be sure that either you really did the math wrong with the intended 40Hz, or it is actually the nyquist shadow frequency of your 40Hz oscillation!