Film series of science-fiction

Why a series of films are so popular?The producers of films, which take less or more successful spot, quite happy to decide on their continuation. Even the universal opinion, the rare sequel that can be better than their predecessors, usually on the wave of the popularity of its previous gain satisfactory cash receipts, which allows them realization ... focus on the next uncontentious Grade science-fiction film series are particularly popular. The best known of these is of course Star Wars, Planet Of The Apes, Star Trek, Terminator and Aliens, but the list is much longer. A number of current films before they shoot is planned for the start of a long series. This is especially if it is to be an adaptation of the classic genre of books, or comics about entranceway willingly supersaturation Although many series of books such as Dune, Foundation and Ender Game intoxicate not even on his own film series, mainly due to technical reasons, would have to meet to avoid becoming a complete failure - movies-science why fiction is traditionally the most expensive film genre, were benefiting from technology and special effects.