Many times the general public associates an actor with a role they play on a long-running television show, not realizing that often that thespian had an active career on the stage first. Jerry Orbach and Sam Waterston on Law and Order, Jason Alexander on Seinfeld, and Patricia Heaton on Everybody Loves Raymond are a few of the many actors who first trained for, cut their teeth on, and professionally performed on the legitimate stage.
The fact is the technique most often taught to American stage actors - some form of the Stanislavski Method - works very nicely on both TV and film. Although there are adjustments to be made going from the stage to television, a well-trained stage actor can usually make those adjustments fairly quickly.
The biggest changes have to do with the subtlety employed by those acting for the camera. Stage actors find that physically and vocally less is more in front of the camera. Additionally, a good film or television actor has a sound sense of how to use the camera frame to their best advantage. An actor like Michael Caine is a master at this.
