Iris

A circle closes in on one part of the frame until everything else is black, or opens out from a point to reveal the scene. The film points at something with the shape of the frame itself.

It came out of the silent era, where a title card and a look were the only other ways to direct attention. The device survives as a period marker and as a way to end on a detail.

Where the circle lands is the whole decision. An iris that closes onto a face, a hand or an object makes that thing the last word of the scene. One that closes onto empty space wastes the move.

Speed sets the tone. A slow close reads as sentimental or wistful. A fast one reads as comic, which is how most silent comedies used it.

It is a mask animated in a compositing step. Render the shot, then shrink a circular matte over it to black. A prompt describing an iris usually returns a vignette, which is a fixed darkening rather than a closing shape.

Use it to end a scene on one detail, to open on a detail and widen out, and anywhere a film is reaching for a period register.

Avoid it in anything contemporary and serious. The shape carries a strong historical accent, and it will read as a joke in a scene that is not one.

A fade dims the whole frame evenly toward a colour, and it points at nothing. An iris closes toward a chosen place, so it picks a subject on the way out.

A wipe crosses the frame with a straight edge and brings in a second image. An iris usually closes to black rather than revealing another shot.

The model returns a vignette. A vignette is a fixed darkening at the corners, and an iris is a circle that moves. Render the shot clean, then animate a circular mask over it.

The second failure is an iris with no target. Say what the circle closes on and where it sits in frame, or the shape shuts on nothing in particular.