ISO

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Definition

Sensor sensitivity setting that brightens or darkens an image.

Advanced

Raising ISO increases brightness but also noise and reduced dynamic range. Modern cameras handle moderate ISO well, but image quality declines at higher values.

Why it matters

Balances exposure when aperture and shutter speed are constrained.

Use cases

  • Low-light event coverage
  • Fast shutter for sports or action
  • Indoor shoots without flash

Metrics

  • Base ISO is commonly 100 or 200
  • Practical upper limit depends on the camera; many remain usable to ISO 3200 or 6400

Issues

  • Excess noise and colour shift at very high ISO
  • Overreliance on ISO instead of lighting

Example

Raising ISO to 1600 to maintain 1/250 at f/2.8 in a dim conference room.