The executioner raised his ax, then stood perfectly still while the camera was stopped. The actor playing the victim was replaced with a dummy and filming resumed to show the ax fall. There are many highly specialized skills that are employed by special effects artists. This specialty is called animatronics. Model makers are among the most highly-skilled of the special effects artists.
Pyrotechnics is the area of special effects devoted to explosions.
Pyrotechnic technicians are specialists in the controlled use of explosives, which are often combined with miniatures and models to obtain a realistic effect. Chroma key is a video technique that combines layers of images. Familiar uses include music videos and weather reports. For instance, in the television newsroom, the weather reporter actually stands in front of a blank blue screen. The computer is the filmmaker's newest tool for creating special effects.