ISO, Shutter Speed, and Aperture — How They Work Together
Every photo's exposure is controlled by three elements: ISO, shutter speed, and aperture. ISO determines your camera sensor's sensitivity to light — higher ISO lets you shoot in darker conditions but introduces digital noise (grain). Shutter speed controls how long the sensor is exposed. Fast shutter speeds freeze motion and darken the image; slow speeds let in more light but can blur moving subjects.
Aperture (f-stop) controls how wide the lens opening is. A lower f-number (f/1.4) lets in more light and produces a shallow depth of field with blurry backgrounds — great for portraits. A higher f-number (f/16) restricts light but keeps everything from foreground to background sharp — ideal for landscapes. Balancing all three lets you capture the exact brightness and look you want.
Exposure Value (EV) is a single number representing the combination of aperture and shutter speed at ISO 100. Bright sunny days are around EV 15; dim indoor scenes around EV 5–8. Use this calculator to understand what scene brightness your current settings are optimized for and adjust accordingly.
Frequently Asked Questions
Yes — this is called equivalent exposure. For example, f/5.6 at 1/250 s and f/8 at 1/125 s produce the same EV. You choose between combinations based on your depth-of-field and motion-blur requirements.
On a sunny day, set aperture to f/16, shutter speed to 1/ISO (e.g., 1/100 s at ISO 100), and you'll get correct exposure. It's a handy rule of thumb for shooting without a meter.
Keep shutter speed at least 1/focal length (e.g., 1/50 s or faster for a 50 mm lens). Use image stabilization when available and brace your elbows against your body for steadier shots.