An interactive camera explainer
How aperture
works
See how the aperture in your iPhone 18 Pro shapes light, focus and blur.
Take a closer look ↓Inside the aperture
An opening
that controls light.
01 · One point, one cone
It all starts
with light.
Every point sends a cone of light. The lens gathers it, then bends it back toward a single point on the sensor.
When that meeting point lands exactly on the sensor, the image is sharp.
One point in the world. One point in the image.
02 · What blur actually is
Why images
blur.
Blur is a slice through a cone. Move the subject closer and the rays meet behind the sensor. Instead of a point, the sensor records a disc.
Rays near the edge of the lens land furthest from the centre. The wider that disc, the softer the image.
03 · Now close the blades
A smaller opening.
Less blur.
Less opening. Less blur. Six overlapping blades block the outside of the light cone, where rays arrive at the steepest angles.
The cone gets narrower. The blur disc gets smaller. More detail comes into view.
Halve the opening’s diameter and you halve the defocus blur. The blades control light; they don’t change where the lens focuses.
04 · Depth of field
More of the scene
in focus.
Choose what stands out. A wide aperture keeps a thin slice of the scene sharp, with softer detail in front and behind.
Stop down and the foreground and background blur discs shrink. The focused centre point stays crisp. More of the foreground and background appears in focus.
From ƒ/1.48 to ƒ/4, defocus discs shrink by about 2.7×. A phone’s small lens already gives it relatively deep depth of field.
05 · Your turn
Experiment with
aperture.
Open up. Stop down. See the difference.
Adjust the focus distance to choose which point is sharp. The pink light is too close to this lens to come fully into focus.
Drag the scene to orbit around it.