Photography: Exposure triangle trade-offs in still images

You raise ISO to freeze motion indoors and the image turns grainy; you open the aperture for light and depth of field shrinks. Shutter speed, aperture, and ISO are coupled levers: changing one shifts what you must give back elsewhere to hold exposure. So "correct" settings are not universal; they follow creative intent—sharpness versus blur, noise versus speed.

Practical use: street, portrait, and travel stills without flash. Edge case: tripod night shots break handheld rules; subject motion and camera shake differ. Cambridge in Colour walks through exposure reciprocity with diagrams [1]; the Cambridge in Colour camera exposure tutorial complements ISO and noise intuition [2].