Credibility within the film's internal logic — not realism, but consistency. Fantasy demands vraisemblance to work.
The cinematic world must be true to itself — that is vraisemblance. Not realism in a naturalistic sense, but internal consistency. A viewer will accept dragons, time travel, or absurd logic as long as the world consistently adheres to these rules. The moment you break your own game rules, you lose them. That is the difference between a fantasy epic that works and one that feels like uninspired improvisation.
On set, this means continuity is not just about focus and costume. It's about emotional and narrative plausibility. If your character is afraid of heights in Scene A, they cannot suddenly jump off the roof in Scene B without explanation. If the world is dark and menacing, a daytime sequence cannot play out with sitcom-like lightness — unless that is consciously part of the narrative. The camera supports this: a world with garish, colorful lights requires a different lighting logic than a somber one.
Vraisemblance also works on a visual level. If you suddenly switch to expressionistic perspectives in a film with a naturalistic aesthetic, it can work, but only if it is diegetically or psychologically justified — for example, through the POV of a confused or injured character. Conversely, a stylized film (anime, graphic novel adaptation) has its own vraisemblance as long as the visual language remains coherent.
The most common mistake is confusing vraisemblance with realism. A horror film with supernatural elements doesn't need real ghosts — it needs a world in which the existence of ghosts has consistent consequences. How do people behave when they believe in the supernatural? How does the mise-en-scène exploit this world? The same applies to editing: every montage decision must reinforce the established logic, not undermine it.
As a cinematographer/DoP, I often only recognize vraisemblance issues in the edit. A scene that "worked" on set feels untrue in context. This means the aesthetic of the shot doesn't fit the world that has been built. Therefore, consistency is not a secondary detail — it is craftsmanship.