• Many physical processes evolve on timescales shorter than the human eye can resolve. Effectively, this means the details of how the process changes with time are lost in a blur. High speed photography, or HSP, is simply photography with extremely short exposure times, yet it can provide a permanent record of the evolution of a process, with detail unattainable with the human eye.

• Recording the complete evolution of a process on film requires a sequence of photographs. The motion-picture method involves taking many photographs during a single "trial" of the process. Essentially, this is a professional pursuit, requiring very sofisticated and expensive equiptment. Obtaining a single photograph while the process is evolving is considerably less complex, and quite inexpensive. With this snap-shot method of HSP, process evolution can be observed by obtaining many snap-shots at different stages in the evolution, though each snap-shot is made on a new "trial" of the process.

• To compare the motion-picture and snap shot methods of HSP, consider a drop of water splashing on a flat surface. To record the evolution of the splash, the motion-picture method would take a photo every ten-thousanth of a second while a single drop was first falling, then splashing. For every second that the drop was filmed, 10,000 images would be recorded. The snap-shot method would take a single shot, say 1 second after the drop began to fall, taking an image of the drop, just before it hit the surface. Another drop would then be spilt, and a photograph taken 1.1 seconds later, recording a picture of the drop as it strikes the surface. The process of spilling a drop and taking a snap-shot is repeated, the photograph being taken 0.1 seconds later each time. For 1 second of evolution of the splash, the snap-shot method would take 10 photographs, each at a different stage in the splash evolution, though each photo is of a different drop. The downside of the snap-shot method is simple - no two drops will have precisely the same splash. On the other hand, a single photograph can provide both a facsinating, and visually spectacular image, and all within the reach of the enthusiust.

• The field of high speed photography was pioneered by Eadweard Muybridge in 1872, in an attempt to prove that a galloping horse has all four hooves off the ground at some point in its stride. Almost 50 years later, Harold E. Edgerton developed a strobe flash, and pushed the field forward as a tool for science. Almost all of the published photographs of high speed events were produced by Doc Edgerton.