A military surplus ``Snooperscope'' has been converted into a stroboscopic shutter for the study of plasma oscillations. Some modification of the surplus item plus the adaptation of commercially available electronic gear has given a device with which periodic fluctuations in the light output of a plasma in the frequency range 103to 106cps can be stroboscopically ``stopped'' and studied. The electric circuits permit a ``lock on'' to a reference signal obtained from the plasma. In this fashion, the stroboscopic shutter will operate even though the plasma oscillations have a frequency jitter greater than 10%. An example of how the device has been used in an investigation of moving striations is given. Other possible uses in the study of plasmas are suggested.