Commercial Photography Practice Exam

Raising ISO increases the sensor’s gain, which brightens the image by amplifying the signal from the light. That same amplification also boosts the random variations the sensor produces—its noise—so the image shows more grain or speckling as ISO goes up. In practice, you’ll see cleaner results at low ISO, and more noticeable noise at higher ISO, especially in shadows or with longer exposures. Modern cameras have improved high-ISO performance, but the basic trade-off remains: higher ISO generally means more noise. That’s why photographers try to keep ISO low and instead brighten the scene with light, a wider aperture, or a longer shutter when possible.