Overview
ISO, aperture, and shutter speed are three variables that always trade off against each other. Change one and you must compensate with another. This guide makes that relationship intuitive.
What You Need
- Any camera with manual mode (DSLR, mirrorless, or a phone with manual controls)
- A well-lit outdoor location to practise in
- A tripod (helpful but not essential)
Steps
Understand what each control does
ISO amplifies the sensor signal — low ISO (100–400) is clean, high ISO (3200+) is noisy. Aperture (f-stop) controls the lens opening — wide aperture (f/1.8) gives shallow depth of field and more light; narrow (f/11) gives more in focus and less light. Shutter speed controls how long the sensor is exposed.
Lock shutter speed using the 180° rule
For video, set shutter speed to 2× your frame rate: at 24fps use 1/50s, at 30fps use 1/60s. This creates natural motion blur. Don't change it during a shoot — inconsistent motion blur is immediately noticeable.
Choose aperture for depth of field
Do you want the background blurry (f/1.8–f/2.8) or sharp (f/8–f/11)? Set this based on creative intent, not exposure. The look of the shot comes first.
Use ISO to correct remaining exposure
After fixing shutter and aperture, if the image is still too dark, raise ISO. If it's too bright in good light, add an ND (neutral density) filter. Never change shutter speed to fix exposure — it destroys your motion blur consistency.
Read the histogram, not the screen
Don't trust your monitor for exposure — use the histogram. Peaks pushed hard to the right edge = overexposed. Peaks bunched left = underexposed. Aim for a gentle hill shape with the peak slightly left of centre.
Pro Tips
- Shoot LOG or flat picture profile if your camera supports it. You'll have far more flexibility when colour grading.
- Overexposure is harder to fix in post than underexposure. When in doubt, expose to the left.
- Use a grey card to set manual white balance — your colours will match shot to shot.