Mastering ISO, Shutter Speed, and Aperture

The exposure triangle—ISO, shutter speed, aperture—controls every photo's brightness, sharpness, and depth. Balance them for perfect shots.

Aperture: Light and Depth

Lens opening size (f-stops). Lower f-number = wider opening.

• f/1.8: More light, shallow depth (blurry background).
• f/11: Less light, deep depth (everything sharp).

Rule: Wide for portraits, narrow for landscapes.

Shutter Speed: Motion Control

Duration sensor exposed to light (seconds/fractions).

• 1/1000s: Freezes action (sports).
• 1s: Blurs motion (silk water, light trails).

Rule: Faster than 1/focal length to avoid shake.

ISO: Sensor Sensitivity

Amplifies light signal.

• ISO 100: Clean, bright conditions.
• ISO 3200: Noisy, low light rescue.

Rule: Lowest possible to minimize grain.

The Balancing Act

More light? Widen aperture, slow shutter, raise ISO. Tradeoffs matter.