Interactive tutorial — no camera required

Master the exposure triangle

Aperture, shutter speed and ISO are the three dials behind every great photo. Learn what each one does, play with a live camera simulator, then test yourself in the quiz.

Start learning Try the simulator

Aperture

Control depth of field — from creamy portraits to sharp landscapes.

Shutter Speed

Freeze a sprinter mid-stride or turn waterfalls into silk.

ISO

Digital sensitivity: rescue dark scenes at the price of grain.

Live view — f/2.8 · 1/250s · ISO 100

Lesson 1 · The big picture

Every photo balances three settings

A photo is just light hitting a sensor. Three settings decide how much light that is and how it looks. Together they form the exposure triangle — change one, and you must compensate with another to keep the same brightness.

Exposure

Aperture How wide the lens opens

Controls depth of field · Wide → blurrier backgrounds

Shutter Speed How long light is collected

Controls motion blur · Slow → blurred movement

ISO Sensor sensitivity

Controls brightness & noise · High → grainier image

Reciprocity — the golden rule

These three settings trade off against each other. f/8 at 1/250s, f/4 at 1/1000s and f/16 at 1/60s all let in the same amount of light — equivalent exposures. Photographers pick the combo that gives the look they want. Hover the nodes to see what each setting controls, then dive into the lessons below.

Lesson 2 · Aperture

Aperture — the eye of the lens

The aperture is an adjustable iris inside the lens. It's measured in f-numbers (f/1.4, f/2.8, f/8…): smaller numbers mean a wider opening — and each full stop doubles or halves the light. Its creative superpower is depth of field: how much of the scene in front of and behind your focus point stays sharp.

f/2.8

Moderately wide

f/1.4 · widef/16 · narrow

Through-the-lens view — drag the f-number

Depth of field at f/2.8: shallow — background melts away

Focus is locked on the person in the orange shirt. At wide apertures (low f-numbers) only a thin slice is sharp; stopping down pulls the whole scene into focus.

f/1.4 – f/2

Portraits, low light

creamy bokeh

f/2.8 – f/4

Events, street, travel

versatile

f/5.6 – f/8

Everyday sharpness

lens sweet spot

f/11 – f/16

Landscapes, architecture

max depth of field

Remember: f-numbers run counter-intuitively — f/1.4 is a big opening and f/16 is a small one. A wider aperture lets in more light, which is why fast f/1.4 lenses cost more and excel in the dark. Beyond ~f/16, diffraction actually softens the image, so more isn't always better.

Lesson 3 · Shutter Speed

Shutter speed — the gatekeeper of time

The shutter is a curtain that opens and closes in front of the sensor. Shutter speed is how long it stays open — from 1/4000th of a second to many seconds. Shorter freezes motion; longer collects more light and lets movement blur into streaks. Every doubling or halving is one stop of light.

Drag the shutter — the runner won't wait

At 1/125 s: visible blur

Notice the trade: slow shutters brighten the image but smear anything that moves — the runner, and soon your own hands. Fast shutters freeze the world but starve the sensor of light.

1/125 s

Crisp & steady

1/4000 s · frozen30 s · silky

The hand-holding rule of thumb

To avoid camera shake, keep your shutter at roughly 1 / focal length or faster: 1/50s for a 50mm lens, 1/200s for a 200mm telephoto. Longer lenses magnify your wobble, so they demand faster shutters. Image stabilisation buys you a few extra stops.

1/1000 s +

Sports, wildlife, splashes

freeze the action

1/125 – 1/250 s

Everyday handheld shots

steady & safe

1 s +

Waterfalls, trails, night

motion as art — use a tripod

In the real world you compensate: a slower shutter that blurs motion also brightens the photo, so you'd stop down the aperture or drop the ISO to match. The simulator at the bottom of this page lets you juggle all three at once.

Lesson 4 · ISO

ISO — the sensor's sensitivity dial

ISO is a digital amplifier. Doubling ISO doubles the brightness without touching aperture or shutter speed — one more stop of light on demand. The catch is noise: random grain that eats fine detail and makes colors muddy. Low ISO is clean; high ISO is gritty.

ISO 100

Base ISO — silky clean

ISO 100 · cleanISO 25600 · grainy

Imagine you're indoors with the aperture wide open and the shutter as slow as you can hold. The photo below is still too dark at ISO 100 — drag the slider up and watch ISO rescue the exposure, grain and all.

Fixed f/5.6 · 1/125 s — only ISO changes

Noise level: invisible

The exposure gets brighter as ISO rises — but random speckled grain rises with it. That's the fundamental trade: ISO buys brightness with image quality.

The photographer's order of operations: set aperture for the depth of field you want, shutter speed for the motion you want, and raise ISO only as much as needed to make the exposure work. Modern cameras are so good at high ISO that a grainy photo you took beats a clean one you missed.

Lesson 5 · Practice

The exposure simulator

Time to fly solo. Pick a lighting scenario, then juggle aperture, shutter speed and ISO to nail the exposure. Watch the photo, the meter and the histogram respond in real time — then try the three challenges.

Sunny day f/8 · 1/250 s · ISO 100

Perfectly exposed

Exposure meter EV 14.0 @ ISO 100

-3 under0+3 over

Histogram — brightness distributionshadows → highlights

Aperturef/8

f/1.4 · more light + blurf/16 · less light + sharp

moderate depth of field

Shutter Speed1/250 s

1/4000 · frozen30 s · silky

everyday range

ISO100

100 · clean25600 · noisy

clean image

Reciprocity in action: one stop more light from any dial is cancelled by one stop less from another. If the needle drifts right (over), speed up the shutter, stop down, or drop the ISO — each pulls it back a stop.

Challenges live checked

Portrait with creamy background

Use a wide aperture (f/2.8 or lower) while keeping the exposure meter within ±0.5 stops.

Freeze the sprinter

Pick a shutter speed of 1/500 s or faster, then fix the exposure with the other two dials.

Hand-held in the dark

Keep the shutter at 1/60 s or faster to avoid camera shake and still land a correct exposure. Try the Night street or Concert scene.

Final exam

Test your exposure instincts

Ten quick questions — instant feedback and an explanation for each. No grades, just growth.

Question 1 of 10Score: 0

You're seeing in stops now

Every question above is really the same skill: predicting how one dial's change must be balanced by another. Master that mental math and manual mode becomes second nature.