ISO SENSITIVITY

ISO — when to raise sensitivity and when to look for light

ISO does not add light to a scene. It determines how the recorded signal is amplified and processed, allowing a faster shutter speed or a smaller aperture. Higher ISO makes working in darkness easier, but usually means more noise and less latitude in highlights and shadows.

The lowest native ISO

The camera’s lowest native ISO — often ISO 100 — is a good choice in daylight, on a tripod and in product photography. It usually provides the most detail and the greatest flexibility in later editing. However, it is not worth sticking to it at any cost if the necessary exposure becomes too long.

Medium ISO: a compromise for handheld shooting

ISO 400–1600 often helps maintain a safe shutter speed indoors, in reportage or under overcast light. A sharp photograph with moderate noise is better than a blurred photograph at low ISO. Check the histogram: brightening a severely underexposed file in editing also reveals noise.

High ISO: when the moment matters more

ISO 3200 and above makes sense for night-time reportage, events, indoor sports and anywhere you cannot lengthen the exposure or use additional light. It is worth checking your own camera’s capabilities beforehand: take a few test shots in your usual lighting and view the files at the intended output size, not just at 100% magnification.

A practical order of decisions

• first choose a shutter speed that will freeze movement or allow a steady handheld shot,
• set the aperture for the required depth of field,
• raise ISO only as much as necessary for a correct exposure,
• when possible, change the lighting, use a tripod or move closer to the light source instead of endlessly increasing ISO.