Depth of field

How much of the frame is in focus, from near to far. Shallow, and the world falls away around the subject; deep, and everything demands attention at once.

Depth of field is the frame's budget of attention, spent through the lens: shallow focus elects one plane and dissolves the rest into suggestion; deep focus refuses to elect, keeping foreground and background in equal evidence and letting the viewer choose where to look.

Each carries an ideology: shallow depth is intimate and authored, the film insisting on its subject; deep depth is democratic and demanding, composition must direct the eye because focus will not. The choice is made by aperture, sensor and distance, but it is felt as a stance toward the audience: guided, or trusted.