1. Post-apocalyptic films Codes and Conventions

2. Location
The location of post apocalyptic films are often in derelict, abandoned areas. This can either be a city that has become overgrown and dirty, or a remote location where there is nothing and nobody around. Both of these location options give the audience the feeling of isolation and abandonment. They both show the audience that the world has become less populated and desolate.
Still from I Am Legend
Shows an abandoned New York City as the location for the film
Location shot of Mad Max: Fury Road, which was filmed in the Namib Desert, Namibia

3. Costumes
Most post apocalypse films have intricate costumes that give the impression that the characters clothes are old, and have been collected over time to become a single outfit that they will most likely appear in for the entire film. This again gives the impression that the characters are truly alone, and cant acquire new or clean clothes, and so they wear the same items.
Some stills from Mad Max: Fury Road, showing that Max wears the same outfit throughout the film, with minor additions, likely picked up during the story

4. Colour
Colour in post apocalypse films tends to be quite cool and desaturated. Tones tend to be blue-ish to convey a sense of coldness and desolation. To contrast this, some films go for a warm colouration as this fits the story line of the global warming and such like.
Pretty much the entire film Children Of Men has the same colour grading, fitting the cold, desaturated theme
28 Days later opening is very cool and desaturated.

5. Story
While all films in the genre have a unique story, they often share a selection of the following conventions:
A tight community of survivors either including the protagonist, or that the protagonist will want to become a part of.
Constant fear of something approaching or an obstacle. Often these films will have some kind of mutated creature or an approaching event to maintain suspense in the film.
Antagonists will often be an opposing group of survivors that have corrupted morals, and believe that they are superior
Death of main characters is a common trope of post-apocalypse films as it conveys the idea that the world has become a dangerous place to live in. In other genres this will likely occur towards the end of the film, however in this genre this is often broken and coud happen at any point.

6. Sound
Music in post-apocalyptic films can vary dramatically within a single film. It can start off being soft, saddening music connoting the feelings of the main character, and become very fast paced, action music during scenes of fighting or conflict. The music will also often be low, background bass, giving the audience the impression that something is lurking or about to happen

7. Shot Types
Post-apocalypse films often use a lot of wide shots and a high angle showing the vast expanse of the world, with little to no one in it. This is normally used at the beginning of the film to establish with the audience, that this is what the world has become. They will also use a lot of panning shots, following the protagonist as they are often the only character there is to follow.
An opening shot from 28 days later, a high angle wide shot that shows the streets of London abandoned
Book of Eli – tracking shot of the protagonist