What does sensitivity mean, how to set it, and what is the impact?

In the traditional film camera, ISO represents the standard of sensitivity speed, in digital cameras, ISO definition and film the same, represents the speed of the CCD or CMOS sensor, the higher the value of ISO means that the sensitivity of the sensor material, the stronger the sensitivity of the ISO formula for S = 0.8/H (S sensitivity, H is the amount of exposure). From the formula, we can see that the higher the sensitivity, the less exposure is required. ISO 200 film is twice as fast as ISO 100, in other words, all other things being equal, ISO 200 film requires half the exposure time of ISO 100 film. Within a digital camera, by adjusting the size of the equivalent sensitivity, it is possible to change the values of how much light is available and how bright the picture is. Thus, the sensitivity also becomes a value that indirectly controls the brightness of the picture.

In the traditional 135mm film camera, the equivalent sensitivity value is the camera's negative response to light sensitivity measurements, usually expressed in ISO digital, the larger the digital that the stronger the sense of rotating light, commonly used to express the ISO 100, 400, 1000, etc., in general, the higher the sensitivity, the thicker the grain of the negative, the magnification of the effect of the poorer, and the digital camera for also This ISO value is used to indicate the exposure used by the metering system, the lower the base ISO, the higher the required exposure. The lower the ISO, the higher the exposure required. 80-200 is enough for daytime shooting, and 400-800 is about right for nighttime shooting. Of course, professional cameras will have the appropriate adjustments, in fact, many brands use the sensitivity as a gimmick, not there at all, too high to use, high sensitivity will be the photo of the early overweight. Image quality