High-speed photography has come a long way. Check out this explanation and videos of a trillion fps camera.
Movies of Combustion Process
WITH a view to improving automobile engines, two German scientists have invented a camera which records on a film the procedure of combustion in auto and other motors under varying conditions.
The fuel at various pressures is injected into a steel chamber provided with glass walls by means of a valve which distributes the finely reduced fuel particles. The light of a 30,000 volt electric spark, formed between two electrodes, is then projected into the injection chamber for the photograph; The time of each exposure is one-millionth of a second.