What Is ISO?

What is ISO?

ISO controls your camera sensor’s sensitivity to light. A low ISO makes the sensor less sensitive, producing clean images. A high ISO increases sensitivity, allowing brighter images in low light—but introduces grain (noise).

ISO is one of the three exposure pillars, alongside shutter speed and aperture.

Why ISO Matters

• Controls brightness in low-light situations.
• Affects image quality: Higher ISO = more noise.
• Essential for action shots in darker scenes.
• Critical for indoor photography when flash isn’t used.

Common ISO Levels

• ISO 100–200: Bright, clean images—ideal for daylight.
• ISO 400–800: Indoor settings with good lighting.
• ISO 1600–3200: Low-light scenes, concerts, night portraits.
• ISO 6400+: Extreme low-light; more grain present.

How ISO Affects Noise

As ISO increases, digital noise becomes more visible. Noise appears as grainy texture or color speckles.

ISO Best Practices

• Use the lowest ISO possible for maximum quality.
• Increase ISO only when needed to maintain proper exposure.
• Use a tripod to keep ISO low in low-light scenes.
• Avoid auto ISO when consistent quality is required.