What does the photo parameter ISO mean?

The camera parameter ISO represents the meaning of sensitivity and measures the sensitivity of the film to light. Sensitivity determines the light required for shooting and the running time of the shutter. Low ISO value means that the photosensitive element needs longer exposure time or more light when shooting, while high ISO value has the opposite effect, and the camera needs less light and shorter exposure time.

The ISO range provided by general digital cameras is100-12800. The lower the value, the lower the sensitivity; the higher the value, the higher the sensitivity. The numerical change of sensitivity is always doubled or halved. For example, the sensitivity is adjusted from ISO 100 to ISO200, which means that it has risen by one step; From ISO 1600 to ISO 100, the display dropped by four grades. Therefore, if ISO is upgraded by one gear, it is necessary to reduce the aperture or shutter speed by one gear to maintain the same exposure.

Generally, in a dim shooting environment, improving the ISO value of the camera can shoot brighter pictures. However, after ISO is improved, there will be obvious graininess and low photo definition. Therefore, the "high ISO noise reduction function" in the camera can be turned on before shooting, thus reducing the influence of noise in the picture on the image quality.

Common ISO scenes are: night photography, ISO can be set to 12800 or higher; Low light photography, ISO can be set between 3200- 12800; The motion state of shooting and standing under normal light can be adjusted between 400-6400; When shooting landscape details, ISO can be reduced to 100-200.