There are two types of realism in film: seamless realism and aesthetic realism. Seamless realism tries to use narrative structures and film techniques to create a "reality effect" to maintain its authenticity. Aesthetic realism, which was first called for by French filmmakers in the 1930s and promoted by Andre Bazin in the 1950s, acknowledges that a "film cannot be fixed to mean what it shows", as there are multiple realisms; as such, these filmmakers use location shooting, natural light and non-professional actors to ensure the viewer can make up her/his own choice based on the film, rather than being manipulated into a "preferred reading.
Aesthetic realist filmmakers use long shots, deep focus and eye-level 90 degree shots to reduce manipulation of what the viewer sees. Italian neorealism filmmakers from after WWII took the existing realist film approaches from France and Italy that emerged in the 1960s and used them to create a politically-oriented cinema.