Crop Factor

The crop factor is the ratio between a reference sensor diagonal — usually full frame — and the sensor actually in use.

What this is about

Crews use the crop factor as a translation dictionary when formats mix: a director who thinks in full-frame focal lengths, a B-camera in Super 35 mode, a drone with a small sensor. Multiply the focal length by the factor and you know which lens gives the matching view on the reference format. That keeps intercut angles consistent and stops the classic surprise of a wide location suddenly framing tight on the smaller chip. It is arithmetic for framing — nothing more, and the mistakes start when people expect more from it.

A term only helps when everyone on set means the same thing by it — so what follows is how it is used, not a dictionary definition.

What runs differently here

Where this differs from the general case:

  • The factor converts field of view, not the lens: physical focal length and its perspective at a given distance stay what they are.
  • Super 35 sits near factor 1.5 against full frame; small drone chips can exceed 2.5.
  • Depth-of-field comparisons need the full chain — lens, distance, stop — not just the crop number.

With TillyGen

When A-camera, B-camera and drone use different sensors, TillyGen's shot list states focal lengths per body, so matching angles is planned, not improvised.

Change one constraint and the consequences travel through the whole plan: affected shots are flagged, the call sheet is regenerated, and nobody keeps working from yesterday's version.

Frequently asked

Does the crop factor change depth of field?

Not by itself. It predicts framing. Depth of field shifts because you pick a different lens or distance to restore that framing — that choice does the changing.

How long does it take to get started with TillyGen?

A first project takes under an hour to set up. There is no configuration phase in which templates and fields have to be defined before the tool produces anything.

Can the results be exported?

Yes — as PDF for the crew, CSV for downstream systems and through the API for anything automated. The plan stays the source; the exports are views of it.