# A hole cut in metal decides the shape you watch

> A metal plate with a rectangular hole cut through it sets the shape of the picture before a single frame reaches the lens, and two plates never agree.

August 21, 2026 · https://justog.club/stories/the-aperture-plate-that-crops-it

Two metal plates, overlapping. The front one is scratched lime green, a wide rectangular window cut
clean through its centre so the fabric underneath shows through. Behind it, a black plate with two
round mounting holes carries a narrower window — taller, offset, a different shape entirely.

Neither plate has ever been seen by an audience, and between them they decided the shape of
everything shown.

## What is an aperture plate?

A flat piece of metal with a precisely cut rectangular hole, fitted at the point where light passes
through the film on its way to the lens.

The hole is the entire design. Everything a projector shows is cropped to that rectangle before
it leaves the machine — the film strip carries more image than the hole lets through, and the extra
is simply not projected. The plate is the last thing standing between the frame and the room, made of
metal because it has to survive heat and constant handling without drifting a fraction of a
millimetre.

## Why are there two plates, not one?

Because different films are shot for different shapes, and the booth has to match the machine to
whichever one is running.

A wider hole gives a wider, shorter rectangle; a narrower hole gives a taller one from the same strip
of film. Swapping the plate is a decision made in the booth after the film has already been shot and
printed — it's a match between the machine and the freight it just received, the same kind of
adjustment [a pair of masking drapes performs a few feet further down the light path](/stories/the-masking-that-moves).
The fine scratches ringing each window are the record of how often it happens.

## What happens if the wrong plate is fitted?

The picture is cropped to the wrong shape, and nobody watching necessarily knows why it looks off.

Fit the wide hole for a film meant to run narrow and the top and bottom of every frame goes missing —
headroom, boom mics, occasionally something that was supposed to stay out of frame. Fit the narrow
hole for a wide film and the picture shrinks inside black bars that shouldn't be there. Either mistake
reads, to somebody who has never thought about aperture plates, as a fault with the film rather than
with a piece of metal in front of the lens.

## Does a design like this belong to anybody?

No. A rectangle is not an invention, and the specific ratios projection uses are technical
conventions, not artwork.

Aspect ratios are published standards, adopted so equipment from different makers agrees on what
shape to project — closer to a screw thread than to a poster. Drawn as two generic plates with no
maker's mark and no film's name on them, there's nothing here that belongs to anybody. Same rule as
everywhere else on this site:
[a format has no owner, a specific work does](/stories/the-print-that-came-back-scratched).

## Does it work for something other than film?

The idea generalises easily: a fixed frame, and a second frame that changes what fits inside it.

A viewfinder, a picture frame with a mat cut wrong, a phone screen cropping a photo shot for
something wider — anywhere a rectangle decides what counts as "in" or "out" is the same joke this
design is making. It reads especially well for anyone in visual production of any kind, where
cropping decisions get made by equipment rather than by taste, the same logic behind
[a test pattern built to be measured rather than watched](/stories/the-focus-card-nobody-sees).

## Isn't this just two rectangles, if you don't already know what they are?

It reads as two rectangles either way, and that's fine — the shapes carry the idea without needing a
caption.

Somebody who has run a projector recognises exactly what they're looking at. Somebody who hasn't
still sees two overlapping frames of different proportions, one behind the other, which is a
legitimate graphic on its own terms. The design doesn't need the viewer to already know the term
"aperture plate" — it needs the two windows to read as clearly different shapes, and cropped hard
against a plain garment colour, they do.

## Does it print well?

Yes — flat metal shapes with hard edges are close to ideal for this.

Two solid colours with a cut rectangle through each is a strong, simple print: high contrast, no
gradients, nothing that needs fine detail to survive fabric. The scratches around each window are the
one place to go coarser than the reference — hairline texture fills in on cotton and reads better
drawn as fewer, heavier marks.

Charcoal and graphite grounds suit the metal. Two inks is enough — one plate colour, one for the
second plate and its window edge.

## How do I get one made?

Describe the two plates at [JustOG](/) — the shape of each window and how worn the metal should
look. Pick a direction, drag the crop frame, see it composited on the real garment, and it's made to
order and shipped.

Designs other people have published are in the [shop](/shop).

One rectangle sits behind another, and the front one always wins.