gen-briefly-explain-iso-and-image-noise-and-one-common-misconcep-fcb4

Briefly explain ISO and image noise and one common misconception about it.

# ISO and Image Noise **ISO** controls your camera sensor's sensitivity to light. Higher ISO values (like 3200, 6400) make the sensor more sensitive, allowing you to shoot in darker conditions or use faster shutter speeds, but they amplify the signal—including unwanted electronic interference—resulting in **image noise**. **Image noise** appears as unwanted grain, speckles, or color variations in your photos, particularly visible in shadow areas and smooth surfaces like skies. ## Common Misconception Many believe that **high ISO "causes" or "creates" noise**. In reality, noise is always present in the sensor; it's just that raising ISO amplifies both the light signal AND the existing noise together, making it more visible. The actual underlying cause of noisy images is typically **insufficient light reaching the sensor**. In fact, underexposing at low ISO and then brightening in post-processing often produces *more* noise than using a higher ISO in-camera, because you're amplifying a weaker signal. When light levels are low, using higher ISO is often the better choice.