What to say about ISO is also about the traditional film camera,
ISOKnown as light sensitivity, it is the international standard for measuring the photographic speed of films used in traditional cameras, and its values reflect the speed of photographic film (in fact, the rate of photochemical reaction of silver and light). For digital cameras that do not use film now, the imaging principle is imaged by the sensor CCD or CMOS and the associated electronic circuitry to detect the intensity of the incident light. The concept of ISO sensitivity was introduced in order to unify the unit of measurement for film used with conventional cameras. ISO also reflects the photographic speed of the camera sensor in the digital camera. The use of different ISO values is equivalent to the different sensitivity film used by ordinary film cameras. The higher the ISO, the higher the sensitivity of the CCD or COMs sensor to light, but it is inherently different from the sensitivity of the film. ISO regulation is actually achieved by electronic means, in fact, the digital camera's sensor by enhancing the photoelectric conversion efficiency of the optical device gain and complex calculation results, it can not fundamentally change the actual effect of the photo. ISO sensitivity represents the exposure value at the same EV, and when the higher ISO is selected, the same exposure can be achieved with a faster shutter speed when the aperture is constant. Conversely, a smaller aperture can be used to maintain the correct exposure when the shutter is not changed. As a result, it is often possible to choose a higher ISO sensitivity when shooting in dim light conditions. Of course, for the SLR camera can also choose to use a larger aperture lens, improve luminous flux. For the general digital camera because the use of fixed lens, only by raising the value of the ISO to be in the light of the situation of normal shooting. The higher the ISO value, the higher the photosensitive capacity of the photosensitive component. The ISO formula is h*s=0.8 (S sensitivity, H is the exposure), from the formula we can see that the higher the sensitivity, the less the demand for exposure. Deformation formula: h=0.8/s, the same exposure amount of the premise, ISO 50 o'clock exposure time is ISO 100 exposure time of twice times. The commonly used ISO values are 100, 200, 400, 800, etc., which are used in light-flooded conditions, while high ISO values are used in the case of insufficient light. In general, the lower the ISO value, the higher the quality of the photo, the finer the detail of the photo, the higher the ISO value, the higher the brightness of the photo, and the quality of the photo will decrease with the increase of the ISO value, the noise will become more and more serious, the image purity is lower. The high ISO has its two sides, so we should try to choose the appropriate ISO value when taking photos, not the higher the better the ISO. In general, in the light of sunny weather, we should set the camera ISO at the lowest level as far as possible, because the light is more abundant, the lower ISO can get better picture purity, and in cloudy or indoor such a low light environment to take pictures, we canProperly improve the camera ISO, to ensure that the picture is bright, not to make the whole picture dark. If you are not sure how to choose Automatic ISO, for today's mobile phones and digital cameras are automatically adjust the function of the ISO. In general, the current card camera ISO set within 400 of the photos taken will not have a noticeable noise, some excellent SLR camera in the ISO 3200 can still guarantee good picture quality. It is worth mentioning that with the rapid development of camera technology in the past few years, the camera's high inductance manic ability more and more good, I believe in the near future we can use a very high ISO to shoot without any noise of the photos. Summary: The higher the ISO sensitivity, the more sensitive the photosensitive element is to the light, the brighter the photo and the more noise. The lower the ISO sensitivity, the less sensitive the photosensitive element is to the light, the darker the photo is, and the fewer noise.
