A very noticeable technical development was the widespread adoption of irising-in and out to begin and end scenes. This is the revelation of a film shot by its appearance inside a small circular vignette mask which gradually gets larger till it expands beyond the frame, and the whole image is in the clear. D.W. Griffith, who used it relentlessly, was responsible for the popularization of this device. By 1918 the use of the iris to begin and end sequences was starting to decrease in the United States, though in Europe it was just starting to become fashionable. At that date it is quite easy to find American films such as Stella Maris in which only fades are used. There were other variants of the simple iris as well and in these the mask opening or closing in front of the lens had shapes other than circular. One of the more frequent of these shapes was the opening slit; a vertical central split appears in the totally black frame, and widens till the whole frame is clear, revealing the scene that is about to start. Eventually the diagonally opening slit appeared as well, and then there was the diamond-shaped opening iris, as in Poor Little Peppina and Alsace (1916), rather than the usual circle. Again, all of these variant forms were very infrequently used, and when they did occur in American films it was usually in the introductory stages. By 1918 the edges of ordinary circular irises were becoming very fuzzy when they were used in American films.
Enclosing the image inside static vignettes or masks of shapes other than circular also began to appear in films during the years 1914-1919, including symbolic shapes such as a cruciform cut-out in the Mary Pickford filmStella Maris (Marshall Neilan, 1918), and Maurice Elvey in Britain put romantic scenes inside a heart-shaped mask in Nelson; The Story of England's Immortal Naval Hero(1918) and The Rocks of Valpré (1919). The most elegant variants occur in some films Ernst Lubitsch made in 1919. In Die Austernprinzessin (The Oyster Princess) a triple layer of horizontal rectangles with rounded ends enclose sets of dancing feet at the frenzied peak of a foxtrot, and in Die Puppe (The Doll) a dozen gossiping mouths are each enclosed in individual small circular vignettes arranged in a matrix.
A new idea taken over from still photography was “soft focus”. This began in 1915, with some shots being intentionally thrown out of focus for expressive effect, as in Mary Pickford's Fanchon the Cricket. The idea developed slowly through the war years, until in D.W. Griffith's Broken Blossoms (1918) all the Close Ups of Lillian Gish are heavily diffused by the use of layers of fine black cotton mesh placed in front of the lens. Heavy lens diffusion was also used on all the other shots carrying forward the romantic and sentimental parts of the story of this film.
