Iris Shot

 An iris shot was a technique frequently used in silent films in which the black circle of the iris partly masks the frame. More often than not, the iris shot was used to signalize the passing of time, similar to a fade-out, fade-in transition. In some cases, more recent and post-silent-era films have employed (or imitated) this technique as an homage to the silent film era or to make a film sequence appear as though it might have been filmed in the silent film era.