The measurement is taken from the film plane to the subject.

Using a focal-plane shutter, exposing the whole film plane can take much longer than the exposure time.

That dimension had to be the same as the distance from the center of the print to the Polaroid's film plane.

Unit focusing: the entire lens is moved back and forth relative to the film plane.

The convex back of the camera indicates that it was made for a camera without a film plane.

A shutter controls the length of time light is allowed to pass through the lens onto the film plane.

A marker for the film plane is engraved on the top of the camera housing.

Shooting without an insert can lead to problems keeping the 120 size film flat against the film plane.

The bellows provides a flexible, dark extension between the film plane and the lens.

Both the lens and the film planes are separate and can be moved independently.