Photography Exposure Triangle Calculator

The exposure triangle is the conceptual framework that governs every photograph ever taken. Three settings — ISO, aperture, and shutter speed — work together to control how much light reaches the sensor. Changing any one of them requires compensating with one or both of the others to maintain the same overall brightness.

Exposure Value formula:

EV = log₂(N² / t) − log₂(ISO / 100)

Where N = f-number, t = shutter speed in seconds.

Each “stop” of light = a doubling or halving of exposure.

The three triangle elements:

1. ISO, Sensor Sensitivity

• Range: 100 (base) → 102400 (extreme)
• Each doubling of ISO = +1 stop (twice as bright)
• Trade-off: higher ISO → more digital noise (grain)
• Rule: use the lowest ISO that still gives correct exposure

2. Aperture, Lens Opening (f-number)

• Full stop sequence: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16
• Each step to a higher f-number halves the light
• Trade-off: wider aperture → shallower depth of field
• Wide aperture (f/1.4) lets in 128× more light than f/16

3. Shutter Speed, Exposure Duration

• Full stop sequence: 1/4000, 1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1s
• Slower shutter = more light, but more motion blur
• Trade-off: below 1/(focal length) → camera shake without stabilization

Worked example: You are shooting in a dim café: ISO 800, f/2.8, 1/60s — correct exposure. The band starts moving fast. You want 1/250s to freeze motion. 1/60 → 1/250 = 2 stops darker (you lost 4× the light). Compensation options: open aperture to f/1.4 (+2 stops), or raise ISO to 3200 (+2 stops), or both (+1 stop each).

Common exposure recipes:

The Sunny 16 Rule: On a bright sunny day, set aperture to f/16. Your shutter speed equals 1/ISO. At ISO 200 → 1/200s. A perfect starting exposure without a meter.