Special effects make a movie better

Post production

Special Effects: The Tricks of the Filmmakers

Dinosaurs, explosions, fireballs, giant waves, spaceships, lightsabers and flashes of light: “How did they do it?” Camgaroo took a look behind the scenes for you.
[Text and image material: Gabriele Lechner, © Camgaroo / LechnerMedia]

Special effects are illusions and deceptions of the eye - a topic that people dealt with centuries ago and that has not lost its fascination to this day. The use of visual effects in film is almost as old as the film itself, only technology and possibilities have changed over the years

The stop trick

One of the simplest visual effects is known as a “stop trick.” A stop trick is how the film is held up in the action. Before shooting continues, props or actors are exchanged. This creates the impression in the finished film that things magically appear or disappear.

Example: Do you remember the pretty TV witch "Genie" - after a snap of the fingers she disappeared as if by magic thanks to the stop trick.

Double exposures

Film material needs a certain amount of light in order to be sufficiently exposed - every photographer knows this and chooses the right combination of aperture, shutter speed, lens and film material depending on the subject to be recorded and the lighting available. In principle, however, a film can be exposed as often as desired. For example, if you wanted to make an actor appear "ghostly" semi-transparent, you would simply have to shoot the same scene twice with the same film material, once with and once without an actor. If you only open the aperture half as far as necessary for both shots, the result would be a correctly exposed image with a semi-transparent actor. But that is by no means the only way to use double exposure. If you protect certain areas of the film material from exposure with the help of a mask, these can later be exposed separately. This technique is ideal for, among other things, doppelganger recordings. This is also called a “split-screen recording”.

Example: In Michael “Bully” Herbig's box office hit “Der Schuh des Manitu” countless of the doppelganger recordings were made using split-screen technology. (Even if these split screens were admittedly only rearranged and reassembled in post-production)


The rear projection (also referred to as rear projection) was the first inexpensive way to use actors who were recorded in the studio in any location. The rear projection was and still does a good job, especially when driving a car. The actors act in the studio in front of a white screen that is illuminated from behind by a projector. This is mechanically synchronized with the camera. Unfortunately, this technique has physical limitations. The projected background of a rear-projection recording always looks a bit dull - a result of the poor performance of the projectors.

Example: In the German submarine drama "Das Boot", the trick technicians made extensive use of rear projection, e.g. to get shots of the sea behind the actors acting on models in the studio.


The front projection can be described as a further development of the rear projection. This process is based on a reflective material, also known as "Scotchlite". This is a highly reflective film made up of small glass beads. This is also used for street signs. The actors are positioned in front of a reflective screen, the projector is at a 90 degree angle to the camera. A semi-transparent mirror at a 45 degree angle now directs the images from the projector onto the screen behind the actors on the one hand, but lets the light of the scene through unhindered to the camera lens, which records the finished overall picture, on the other.

  • Animatronics mask

  • A typical rear projection installation

  • The front projection is a further development of the rear projection and provides much more contrasting backgrounds than its "predecessor".

  • Clark, the hero of the hit series "Superman" only flies through the clouds thanks to the bluebox / greenbox technology.