The third and last element of the exposure triangle is the “ISO”
The ISO measures the sensitivity of the image sensor. It stands for “International Standards Organization”, and it is a standardized industry scale for measuring sensitivity to light.
ISO figures starts by 100 in most of the cameras till more than 20 thousand and this highest figure differs from a camera to another.
Like the other elements ISO controls 2 things.
-First is the quantity of light coming to the camera .. a bigger ISO number lets more light into the camera & vice versa.
-Second is the image quality .. what does this mean?
Simply the lower the number the less sensitive your camera is to light and the finer the grain.
A bigger ISO number may lead to noise and a bad quality picture.
Anyone needs to understand it more, please tell me.