Although there are not many codes and conventions of French New Wave I have looked at other genres which influenced many French New Wave directors.
Film Noir:
Film Noir cinematography is often distorted, skewed and uncomfortable to look at.
- Low and high angles.
- Extreme close-ups.
- Deep focus.
- Depth of field.
- Reflections, views and faces obscured through objects.
- Use of Dutch tilts* or irregular framing shots.
*Dutch tilt, Dutch angle, oblique angle, German angle, canted angle, or Batman Angle are terms used for a cinematic tactic often used to portray the psychological uneasiness or tension in the subject being filmed. A Dutch angle is achieved by tilting the camera off to the side so that the shot is composed with the horizon at an angle to the bottom of the frame.
Film noir locations used everyday urban settings to make what was happening seem more real to the viewer. Moved from crime movies only happening at the wrong end of town and dodgy areas to everyday locations.
They used high contrasted images and dark black and white, (few greys).
Italian Neo-realism:
Before the indies and even before the French New Wave, Italian neo-realism staked out new cinematic territory. One of those blanket terms that mean all things to all people, neo-realism has few absolutes, though there are elements that set the Italian version distinctly apart. Screenwriter and poet Zavattini wrote an actual manifesto to guide these films, but their creation was just as much a result of timing, chance and fluke.
Stylistically, Italian Neorealism was:
1. an avoidance of neatly plotted stories in favor of loose, episodic structures that evolve organically
2. a documentary visual style
3. the use of actual locations--usually exteriors--rather than studio sites
4. the use of nonprofessional actors, even for principal roles
5. use of conversational speech, not literary dialogue
6. avoidance of artifice in editing, camerawork, and lighting in favor of a simple "styless" style.