📷 Photography

The Exposure Triangle

Exposure balances aperture, shutter speed, and ISO.

• Aperture: controls light volume and depth of field
• Shutter: controls time and motion blur
• ISO: controls sensitivity and noise

> Mastery means trading one variable for another while preserving exposure.

Think in stops: changing any leg by one stop requires compensating with another.

Aperture and Depth of Field

• Wide (f/1.4–f/2.8): shallow depth, strong subject isolation, more aberrations
• Mid (f/4–f/8): balanced sharpness, common for portraits
• Narrow (f/11–f/16+): deep focus, risk of diffraction

Depth of field depends on:

1. Aperture

2. Focal length

3. Subject distance

4. Sensor size

Use background distance creatively to enhance blur (bokeh).

Shutter Speed and Motion

Shutter speed shapes how motion appears:

• Fast (1/1000s+): freeze action 🏃
• Medium (1/60–1/250s): natural gestures
• Slow (1/2–1/30s): motion blur, light trails
• Very slow (seconds+): long exposure, smoothing water, star trails

Remember camera shake: use at least 1/focal length on full-frame (e.g., 1/100s for 100mm) unless stabilized.

ISO, Noise, and Dynamic Range

Raising ISO amplifies signal and noise. Modern sensors tolerate high ISO, but dynamic range usually declines.

Guidelines:

• Use the lowest ISO that gives a workable shutter and aperture
• Expose carefully at low ISO for maximum latitude
• High-ISO noise is less problematic than motion blur when capturing decisive moments

Metering and Histograms

In-camera meters assume scenes average to mid-gray. High-contrast scenes confuse them.

Use the histogram:

• Left: shadows
• Middle: midtones
• Right: highlights

Avoid clipping unless intentional. For digital, slightly bias exposure to protect highlights, then lift shadows in post (especially on modern sensors).