The important exposure parameter iso refers to the exponential Tang Wei of the camera.

1.ISO stands for sensitivity, which is also the abbreviation of International Organization for Standardization, which quantifies sensitivity.

2. Sensitivity is a measure of the sensitivity of negative film to light, which is determined by sensitivity measurement and measurement of several values. Films that are less sensitive to light need to be exposed for a longer time to achieve the same imaging effect as photosensitive films, so they are usually called slow films. Highly sensitive negatives are therefore called fast negatives.

3. Whether it is digital or negative photography, in order to reduce the exposure time, using higher sensitivity usually leads to the decline of image quality (due to thicker negative particles or higher image noise or other factors). Basically, the higher the sensitivity, the worse the photo quality.