The Exposure Triangle — An Interactive 3D Simulator
Aperture, shutter speed, and ISO work together to make a photo brighter or darker — each with its own side effect. This simulator shows all three in a realistic 3D room you can orbit and relight.
Moderate depth of field
Fan blades frozen
Clean
Exposure
Room lighting
Stops
Each step is one stop — double or half the light. Changing aperture, shutter, or ISO by one stop changes exposure equally, but has a different side effect.
The renderer scales the scene's light by 2EV, so the meter tracks a real optical simulation — not a pre-made bright/dark photo pair.
Three controls, one exposure
Aperture (f-number) controls how much light passes through the lens. Shutter speed controls how long the sensor is exposed. ISO controls how sensitive the sensor is. Change any one and the photo gets brighter or darker.
Aperture and depth of field
A small f-number (wide aperture) lets in more light but creates a shallow depth of field — a blurred background behind a sharp subject. A large f-number (narrow aperture) keeps more of the scene sharp.
Shutter speed and motion
A fast shutter (like 1/1000s) freezes motion but lets in less light. A slow shutter (like 1/8s) lets in more light but records motion blur.
ISO and noise
Raising ISO brightens the image without changing the lens or shutter, but it also amplifies noise — the grainy texture that appears at high ISOs.
Stops and equivalent exposures
A stop is a doubling or halving of light. f/4 at 1/250s gives the same brightness as f/5.6 at 1/125s — one stop more aperture, one stop less shutter — but with a shallower depth of field. Watch the EV readout stay the same while the side effects change.
Frequently asked questions
What is the exposure triangle?
The exposure triangle is the relationship between aperture, shutter speed, and ISO. Together they determine how bright a photo is, and each one has a side effect: aperture controls depth of field, shutter speed controls motion blur, and ISO controls noise.
What is a stop of light?
A stop is a doubling or halving of light. Opening the aperture by one stop, slowing the shutter by one stop, or raising ISO by one stop all double the brightness — but with different side effects.
Why does a wide aperture blur the background?
A wide aperture (a small f-number like f/1.4) creates a shallow depth of field, so only a thin slice of the scene is sharp and the background falls out of focus. A narrow aperture (a large f-number like f/16) keeps more of the scene in focus.
Why do high ISOs look noisy?
Raising ISO amplifies the sensor signal, which also amplifies the underlying electronic noise. Higher ISOs brighten the image but produce visible grain, especially in shadows.