High speed photographic studies of the equilibrium and stability of the atc tokamak have been performed. Framing speeds of 26000 pictures per sec were achieved as were effective shuttering times of 5 musec. Streak photography with time resolution of 15 musec was also performed. Studies of the disruptive instability enabled the radial expansion velocity of the plasma cross section to be determined. Differences in the form of the negative spike on the loop voltage between disruptions which led to the plasma interacting with the limiter and those which did not were found. A histogram giving the relative occurrence of disruptive instabilities vs the q of the plasma just before the disruption was constructed.