To stop action you should...

• A. Use a larger aperture
• B. Increase ISO
• C. Use a tripod
• D. Use a faster shutter speed

Answer: (D)

To stop action, you freeze motion by shortening the exposure time. A faster shutter speed reduces the amount of time the sensor is collecting light, so moving subjects blur less or not at all, giving a crisp image. The exact speed you need depends on how fast the subject is and how close you are, but the principle holds: quicker shutter equals less motion blur. Other tools can help in different ways—opening the aperture or raising ISO can compensate for light so you can use a faster shutter, but they don’t directly stop motion by themselves. A tripod reduces camera shake, not subject movement.