Movies that had special effects, sometimes well done and other times done in a funny or noticable way. Special Effects can often be the deciding factor in making a movie a success. How to make a monster movie come alive is the job of the special effects people.
A frame or a few frames at a time are taken of Lon Chaney's face and then more make up and hair are added and more frames are taken and in an hour or so it looks on screen as though everything smoothly transformed from a man's face to a wolfman's face. High tech for the time.
Small gorilla model filmed in stop motion or frame by frame. Each arm, leg or head movement filmed over hours of one frame at a time with each frame having a slightly different picture as the model's arms or legs are moved. That movie sequence can then be used behind an actor for a matte shot or what today we call chroma key or green or blue screen. The hand of Kong was actually a big on stage set which had the mechanism for moving and seeming lifelike.
Miniature people dancing on a table top were done very well in this movie. This looks so real it is hard to believe there were not some real little people dancing on a table. This can be done by mixing some scenes (cloning) or using matte shots of the tiny people who are filmed from high above with oversize props.
For scenes in which Claude Rains, the actor who portrayed The Invisible Man, was wearing a shirt or some clothing but he was invisible, there was a need to develop a believable visual. Claude Rains wore a black velvet suit and was photographed in a black velvet room with even his head covered by the black material. He then could put on a shirt or move something and only the clothing or object being moved would be in the finished film clip. That film clip could then be overlaid into any scene and it appeared an invisible man was moving about. That can be done today with a green screen and an actor in a green body suit and hood.
This video uses an overlay and green screen approach to creating an illusion. It was made with a low cost video editor called Magix Pro 14.
Boiling chemicals in a mad scientists lab and fog scenes have often been done in movies using dry ice. Dry ice can be placed in a hot liquid and it will send up smoke that is the color of the liquid. For a fog scene most current movies use a chemical smoke maker, but dry ice can be used just below and in front of the camera in a heated liquid to make the scene appear foggy or smokey. Hollywood is probably the only place where workers get a "smoke check" when they do a smoke scene using special effects.
If the script calls for the man to turn into an ape or wolf, a two way mirror can be used. A person who is wearing the ape suit can be standing about ten or fifteen feet in front of the camera but just out of frame to the right side. A two way mirror can be placed between the actor playing the man and the camera. The mirror is at a 45 degree angle to the camera so if it is a mirror we see the ape but if it is a window we see the man. They are both carefully positioned to superimpose over each other. When the man is well lighted and the ape is in the dark, the camera shoots right through the glass which is transparent. As the light on the man is slowly dimmed and the lights are turned on for the ape the ape form gradually replaces the man as the ape's reflection is now seen. Soon the ape is completely lit and the light is turned off for the man behind the two way mirror.
Models often can be blown up with explosions which are then shown at slow motion to appear more realistic. That is also true of model trains and car wrecks. Think of ways to do your scene by overlaying one video clip on top of another.