Increasing ISO in the exposure triangle primarily achieves what effect?

• A. Increases brightness and adds noise.
• B. Increases brightness but reduces noise.
• C. Decreases brightness.
• D. Only affects color balance.

Answer: (A)

Raising ISO makes the sensor more sensitive to light by amplifying the electrical signal it receives. That amplification brightens the image at the same shutter speed and aperture. But that same amplification also boosts the camera’s noise, or grain, especially in darker areas. So the main effect is a brighter image with more noise—the trade-off you’re balancing when you adjust ISO.

This isn’t about changing color balance, which is the role of white balance, nor does it decrease brightness.