What is ISO and how to set it up
However, what is ISO in the camera settings?
ISO is a parameter indicating the level of sensitivity to light of its light-catching element (matrix or film). Mostly indicate the ISO limits for cameras (cameras). Although, the same parameter can be met not only on the camera, but, for example, on the flash. For a flash, leading numbers are usually indicated when using one of the ISO 100, or 200 values. The ISO sensitivity is indicated in special ISO system units. The ISO number expression itself can take any integer expression from 1 to infinity. For example, on my SB-900 flash, you can set the ISO to 1 (unit) to 12,500, and on my Nikon D40, you can set the ISO value from 200 to 1.600.
Less is better!
The higher the ISO value, the more sensitive the matrix. It is very important to understand that the higher the ISO value, the less time it takes for the matrix or film to scan the image from the lens. For clarity, I will give an example: we shoot in the evening, the light is low, the camera is set to ISO 100, and the camera in the aperture priority (or in any other mode) indicates that the image will be taken with a shutter speed of 1 / 20s. This is a very long exposure, and in doing so we can get a blurry frame. Therefore, to reduce the shutter speed you need to increase the ISO. For example, we have increased the ISO to 800, then the shutter speed will decrease by 8 times and become 1 / 160s (one hundred and sixtieth seconds). If it were not for the noise, one could always shoot at high ISO and never worry about exposure, due to the noise, you need to lower the ISO and increase the exposure and, in addition, worry about not getting a blurry frame.
Raise, close, reduce!
Exposure parameters, aperture values and ISO interchangeable. The amount of light needed by the camera to build an image can be the same for different three values of shutter speed, aperture and ISO. So, at 1 / 60s, F2.8, ISO 100, the camera will receive as much light as at 1 / 30s, F2.8, ISO 50 or 1 / 60s, F5.6, ISO 400. In order to compensate raising the ISO, you need to close the aperture or reduce shutter speed. The opposite is also true. You can increase the shutter speed, open the aperture and lower the ISO.
ISO affects noise
In fact, the ISO value is also responsible for the appearance of noise in the photo. Noise is a parasitic distortion in a photograph. Usually it is called so – noise, grain, etc. The higher the ISO, the greater the noise. And the smaller the ISO, the smaller the noise. To get the best possible high-quality photograph from a camera, you need to shoot at the maximum allowable low ISO. Very often it is ISO 200, 100, 50, sometimes they can be designated as Lo1.
Super high and super low ISO
Many cameras have an expanded range of ISO values — usually software-programmed ISO, and they are referred to as Hi1, Hi2, etc. For example, for a Nikon D200 HI1 camera, the ISO 3200 is equivalent to ISO 6400. Always Remember that shooting at such enhanced ISO values will almost always have a very strong picture noise effect. I strongly do not recommend shooting in the extended high ISO range on any cameras. Also, the range can expand to the lower side, so the Nikon D90, D300, D700 camera has the values lo 1, lo 0.3, lo 0.7 as equivalents for ISO 100, 160, 130. What is the gain from expanding to the low ISO range in my article ISO lo1. Some cameras, in fact, do not have the hardware implementation of ISO, I made such a conclusion by conducting an experiment with ISO.
How to choose an ISO camera?
When choosing a camera, always look at the minimum and maximum ISO values, and also remember that in 90% of cases you will not have to shoot at the highest ISO levels, as they often will not be able to provide normal image quality. Therefore, professional photographers have the concept of working ISO. By working ISO is meant the maximum ISO value at which the camera can produce an acceptable result. The trick is that, unlike aperture and shutter speed, which give completely the same values on all cameras, the same ISO on different cameras can produce different values of noise. Therefore, in one camera, the working ISO will be 800, and in another, the working ISO will be 3200. For example, on a Nikon D700 camera, you can take pictures of acceptable quality at ISO 3200, while on a Nikon D200 in ISO 3200 mode (Hi1) you can already not a photograph, but complete nonsense. Very much the difference in noise of ISO is felt on digital soap dishes, where already at ISO 400 digital noise is often very visible, and at the same time on ISO 400 mirror cameras is quite working.