Methodology

FocalSim uses standard thin-lens depth-of-field formulas. Calculations run locally in your browser and do not depend on a camera database or external API.

Hyperfocal distance

H = f² / (N × c) + f, where f is focal length, N is f-number and c is circle of confusion.

Near and far focus

Near and far limits are derived from hyperfocal distance and the selected focus distance. When focus reaches or passes the hyperfocal distance, the far limit is infinity.

Field of view

Horizontal field of view is calculated as 2 × atan(sensor width / (2 × focal length)). Vertical field of view uses sensor height.

Circle of confusion

Defaults are 0.030 mm for full frame, 0.0197 mm for 1.5× APS-C, 0.0186 mm for Canon APS-C and proportionally smaller values for smaller formats.

Limitations

The background preview shows relative blur for learning and planning. It is not a pixel-perfect lens render. Aberrations, focus breathing, aperture blades, subject texture and viewing conditions can change the real result.