What is ISO and how to configure it

ISO value is one of the most important parameters when shooting, along with such values ​​as excerpts, aperture and white balance. ISO is often referred to as ISO sensitivity, ISO level, or simply photosensitivity matrix or film.

Poster for the article. What is ISO?

Poster for the article. What is ISO?

Still, what is ISO in the settings of the camera?

ISO Is a parameter indicating the level sensitivity to light of its light-picking element (matrices or films). Basically indicate the limits of ISO for cameras (cameras). Although, the same parameter can be found not only on the camera, but, for example, on the flash. For flash, a guide number is usually indicated when using one of the ISO values ​​of 100, or 200. ISO sensitivity indicated in special units of the ISO system. The ISO numeric expression itself can accept any integer expression from 1 to infinity. For example, on my flash SB-900 you can set the ISO from 1 (unit) to 12,500, and on my camera Nikon D40 You can set the ISO value from 200 to 1.600.

Less is better!

The higher the ISO value, the more photosensitive 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’ll give an example: we shoot in the evening, there is little light, the camera is set to ISO 100, while the camera in the aperture priority (or in any other mode) shows that the picture will be taken with shutter speed 1 / 20s. It is very long excerpt, and at the same time we can get a blurry frame. Because, to reduce shutter speed need to increase ISO. For example, we increased the ISO to 800, while doing so excerpt decrease by 8 times and become 1 / 160s (one hundred and sixtieth seconds). If it weren’t for noise, then one could always shoot at high ISO and never worry about exposure; due to noise, you need to lower ISO and increase exposure and in addition worry about not getting a blurry shot.

Raise, close, reduce!

Parameters excerpts, aperture values ​​and ISO are interchangeable. The amount of light needed for the camera to build the image can be the same for different three values excerpts, aperture and ISO. So, at values ​​of 1 / 60s, F2.8, ISO 100, the camera will receive as much light as at values ​​of 1 / 30s, F2.8, ISO 50 or 1 / 60s, F5.6, ISO 400. In order to compensate raising ISO, you need to close the aperture or reduce shutter speed. The opposite is also true. You can increase shutter speed, open aperture and lower 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 they call it that - noise, grain, etc. The higher the ISO, the greater the noise.. And the lower the ISO, the less noise will be. To get the best possible high-quality photo from the camera, you need to shoot at the highest permissible low ISO. Very often it is ISO 200, 100, 50, sometimes they can be designated as Lo1.

Noise difference at different ISO values

Noise difference at different ISO values

Super high and super low ISO

Many cameras have extended ISO range - usually this is software wrapping ISO, and they are designated as Hi1, Hi2, etc. For example, for a camera Nikon D200 HI1 is equivalent to ISO 3200 and on camera Nikon D90 HI1 is equivalent to the value of ISO 6400. Always remember that when shooting at such advanced ISO values ​​there will almost always be a very strong picture noise effect. I strongly recommend not shooting in the extended upper ISO range on any cameras. Also, the range can expand in a smaller direction, so the camera Nikon D90, D300, D700 matter 1, 0.3, 0.7 as equivalents for ISO 100, 160, 130. What is the benefit of expanding to a low ISO range, see my ISO article lo1. Some cameras, in fact, do not have a hardware implementation of ISO, I made this conclusion after ISO experiment.

Noise at different ISO. Example 1 to 1 increase

Noise at different ISO. Example 1 to 1 increase

With which ISO to choose a camera?

When choosing a camera, always look at the minimum and maximum ISO values, and also remember that in 90% of cases you do not have to shoot at extremely high ISOs, since often they simply can not ensure normal image quality. Therefore, professional photographers have ISO working concept. By working ISO is meant the maximum ISO value at which the camera can give an acceptable result. The trick is that unlike the diaphragm and excerpts, which on all cameras give completely the same values, the same ISO on different cameras can give different noise values. Therefore, in one camera, the working ISO will be 800, and in the other, the working ISO will be 3200. For example, on the camera Nikon D700 images of acceptable quality can be obtained at ISO 3200, while at Nikon D200 in ISO 3200 (Hi1) mode, it’s already not a photograph, but complete nonsense. The difference in ISO noise is very strongly felt on digital soap dishes, where digital noise is often very visible already on ISO 400, but at the same time, ISO 400 is quite operational on SLR cameras.

What affects noise at high ISO?

The noise level at high ISO is very much affected matrix size camera. The larger the matrix, the less noise. Given that the matrix is ​​very small in compact cameras, it produces a huge noise level. The explanation can be very simple at the pixel size. The large matrix has large pixels that can absorb a lot more light and thus make a strong electrical signal. It is logical that 12MP with soap dishes and 12MP with Nikon D3s will produce different noise levels at high ISO. More information in my article. matrix size has the meaning.

How is ISO measured?

ISO as well as shutter speed and aperture accepted count in the footstepseg ISO 100, ISO 200, ISO 400, etc. The difference between ISO 800 and ISO 400 is exactly two times or one stop, and between ISO 100 and ISO 1600 exactly 16 times, or 4 stops. It's too bad that cameras generally only allow ISO changes by stop value. So, for Nikon D40 it is possible to manually set ISO only 200, 400, 800, 1600, HI1, and you cannot set an intermediate value such as ISO 250, 320, 500, etc. On more advanced cameras, you can set intermediate values, but still fine ISO control is practically not in any cell. The most interesting thing is that in the automatic ISO mode, the ISO sensitivity can take on any values, such as 110, 230, 1400, etc.

Auto ISO

On almost all cameras available auto ISO. This means that the camera itself will select the optimal ISO value. Auto ISO It is very convenient when shooting with poor lighting, when using it, the camera can squeeze the maximum quality. Basically, when using auto ISO, The maximum shutter speed and maximum ISO value must be indicated. Some cameras adjust the ISO to the focal length of the lens to prevent blur when shooting with your hands. Who cares, you can read how the function of automatic control of ISO sensitivity works on modern Nikon central control centers.

Auto ISO Example

We decided to photograph the cat at home in the dim light of the lamp. We have a 60mm lens, to avoid hand shake, you need to shoot at a shutter speed no longer than 1/60, so we set the maximum shutter speed to 1/60 in the automatic ISO settings, as well as the maximum allowable ISO 800 in order to get the maximum picture quality. When photographing, the camera will try to lower the ISO, and adjust the shutter speed. If the shutter speed is shorter than 1/60 and the ISO is less than the minimum, the camera will automatically extend the shutter speed and lower the ISO and will do so until it hits the preset limit of 1/60 second, while we get the maximum allowable shutter speed and the lowest possible ISO for photographing a cat. If there is enough light, the camera will set ISO 100 (or any minimum acceptable) and any desired shutter speed no longer than 1/60. If the light is catastrophically small, then the camera will set the maximum possible ISO and forcibly increase the shutter speed for the correct exposure. Generally, I I strongly recommend experimenting with auto ISO in aperture priority modesince the operation of automatic ISO is quite specific.

Little trick

When using automatic ISO and flash, it is better to turn off the auto ISO, since very often the camera goes crazy and where you can really lower the ISO, the camera sets the maximum specified and takes a picture with flash. Anyway, if there is a flash, then you can safely use the lowest available ISO.

Another little trick

On a number of DSLR cameras in the auto ISO mode, you can set the maximum ISO in the menu, as well as the minimum. Sometimes, to set the minimum ISO, you just need to set the desired ISO value with the selector, for example, 800. And then, with the maximum specified ISO 1600, you get a working range of ISO 800-1600 at which the camera will work - a very, very useful thing.

Golden ISO Rule

Always remember the golden rule - you need to shoot at the lowest possible ISO. As soon as there is an opportunity to lower the ISO - do it. Raise the ISO only when needed, such as when the shutter speed at low ISO is too slow for normal handheld shooting. To lower the ISO as low as possible - open the aperture as much as possible. If there is a flash, do not use high ISO. Although, sometimes with the flash, you can shoot at high ISO (details here).


Value ISO directly responsible for photosensitivity and noise level. The higher the ISO, the greater the noise and the worse the photo. Lower ISO - the better the photo, but the longer the shutter speed.

 Have a question? You can ask in the comments. Thanks for attention. Arkady Shapoval.

Add a comment:



Comments: 150, on the topic: What is ISO and how to configure it

  • Alexander

    Have you done any research in which cameras is fully software, and in which there are hardware implementations?
    IMHO, you need to shoot at low ISOs only in extreme cases, because This thing is purely software and spoiling colors and DD. (Base ISO usually 100-200)

    • Arkady Shapoval

      Usually software isos have some tricky name, like LO 1, by which it immediately becomes clear where the markup is. To distinguish even on tests and say where software implementation is, and where hardware with 100% will be very problematic, an example is ISO 100 (Lo 1) Nikon D90, ISO 200 (basic), DD and colors at 100 fall very, very little, since most likely there is an algorithm to combat this.

  • Alexander

    I just have a suspicion that in most cameras there is no hardware ISO change at all.

    • Arkady Shapoval

      I conducted an analysis, and indeed, there is no hardware implementation. Here is my article about ISO software implementation

  • Igor

    Auto ISO. Wonderful function.
    In my camera, ISO: 100-6400.
    What is the maximum (upper) limit of the ISO set to get normal pictures. From a practical point of view?
    (It is clear that there are a lot of conventions - but still.)

    • Arkady Shapoval

      I would be happy to tell you if you indicated the model of your camera.

  • Igor

    Nikon D800

    • Arkady Shapoval

      Then, the values ​​of 100-6400 will be just right.

  • Igor

    Sorry, but you turned it down. In general, I am always always at ISO 100-200, well, I shot at a maximum of 400-600.
    (I didn't have Auto ISO). And here ... on the whole scale. You yourself have seen the pictures on the Internet, .... At the upper border of ISO ... ... very for an amateur. With all due respect to Nikon. And I don’t shoot booze and theaters. (so that at least something to remove - or not something - for me there is no such problem)

    • Arkady Shapoval

      Please note that if you had specified the problem, the range could have been chosen even more modest. But the Nikon D800 itself is interesting for its ability to “night” shooting at high ISO, so it’s silly not to use all its capabilities to the fullest.

    • Timur

      Igor, I'm sorry but to buy the D800 to ask for advice on how to set the ISO, you turned it down.
      I have a good quality on the D7000 at ISO 800 (if necessary) and no noise is visible.
      On the D800, this is at least 1600.

  • Igor

    Opportunities - Opportunities. I am not satisfied with the QUALITY of this feature at the upper ISO.
    I recently have a camera, I'll have to find out empirically.
    Thank you.

  • Oleg

    I have a Nikon 5100, ISO always costs 100 and take pictures under different weather conditions, whether I am doing the right thing and what is the golden mean of ISO in sunny and cloudy weather.

    • Arkady Shapoval

      ISO can be 100, but at the same time AutoISO works, which during shooting takes any value from the acceptable ones. There is no golden mean - everything needs to be looked at according to the circumstances, otherwise it would have been possible to turn on ISO 1600 and shoot at it always.

  • Ivan

    Very useful work. Everything is described clearly and accessible. "Not scary" to start ...
    Thank you!

  • m.zh.t

    give a transcript of this word))))

  • Nicholas

    please tell me nikon d 7000 18-105vr which iso maximum can be used so that there is no noise, and is it worth it to turn on noise reduction for high iso and for slow shutter speeds in the settings

    • Arkady Shapoval

      It all depends on what level of image quality you need. If it's good, then don't raise the ISO above 1200. If you're shooting in JPEG and don't worry about details, you can turn on noise reduction for high ISO. For long exposures, I do not include it, since this function simply eats up the frame buffer.

      • Lenar

        Hello! I have a question - I recently switched from canon to nikon, sort of figured out the camera, but for some reason on a sunny day when shooting portraits, the background is too bright, in the lights, you almost always have to pull out the lights by almost -100 (in Lightroom) if at least the sky got a little bit. Can you please tell me what could be the reason?
        Nikon d7100 + Nikon 35 mm f1.8 g camera, I usually shoot at ISO 100 in mode A (aperture priority).

        • Artem

          Faced the same. Set the correction to -0.7.

          • Lenar

            Thanks, I will try! I don’t understand, is the same lens sinning? Or is it the camera itself?

  • Nicholas

    I understood everything; I will not turn on the suppression, I think I’ll shoot in JPEG + raw the card allows (32 gig) I will not turn on the suppression because I'm interested in the high quality of the pictures I want to squeeze the maximum out of this camera

    • Stanislas

      "I will not turn on suppression because I am interested in high quality images"

      Feel free to turn on the suppression at high ISO, since on your camera it starts to work very smoothly and only after ISO 1600. Before that, it does not turn on at all. Moreover, only at ISO 2500, it begins to be fully utilized.
      If you shoot in RAW, then generally hammer on this function, since it does not affect the picture in any way and only makes corrections in the converter. And in Jpeg, they shoot at high ISOs only so that there is nothing more to do with it, so noise canceling will be very useful.

      And the high quality of the pictures does not depend entirely, only on ISO and noise reduction. I took great photos on the ISO 6400 on my D3S when shooting competitions. Shorter shutter speeds are more important.

  • Zhenya

    Photosensitivity From 100 to 1 ISO units in increments of 600/1 EV. What exactly is it in 3/1 increments?
    Nikon D3000 camera. I select a fotik. I read the specifications. I am an amateur, but I want high-quality photos. I'm interested in your opinion about this fotik.

    • Arkady Shapoval

      You will find my opinion in the section on the Nikon D3000. Step 1 \ 3 means that the ISO changes not in whole stops, but in thirds, that is, from 100 to 1600, you can set ISO 125, 160, 200, 250, 320, 400, 500, 640, etc., and not 100, 200, 400, 800

  • Anastasia

    A kakoj range ISO vi posovetyjete dlja Canon EOS 650D?
    Spasibo :)

    • Arkady Shapoval

      Takoiy, kakoiy budet nuzhen dlia s ”emok v kazhdoiy otdel'noiy situacii.

  • Asdf

    Joker's thoughts are direct)))

  • Albina

    Hello Arkady !!! Very interesting article, thanks!
    I'm just learning to take pictures in manual mode) I have a canon EOS 60D. Could you tell me what minimum ISO will be optimal for this device?

    • Arkady Shapoval

      The best ISO is the lowest acceptable, in this case ISO 100

  • Kettle

    Good afternoon. From all of the above, I concluded that with poor lighting you need to shoot at a bit too high ISO, and with good light at low. Did I understand correctly ?!

    • Arkady Shapoval

      Yes, right.

  • Kettle

    Although how not to use the apricot at high ISO then

    • Arkady Shapoval

      Easy to shoot at low / medium ISO with flash

  • Kettle

    Another question. I heard that on the D5100 often get blurry photos, how to deal with it?

    • Arkady Shapoval

      Usually blur due to short shutter speed when shooting handheld, general guidelines here - https://radojuva.com.ua/2012/01/how-to-make-photo-by-hand/

      • Stanislas

        Here you are mistaken. Grease due to long shutter speeds.
        I think this is just a typo.

      • Sasha

        No, because of the long exposure time, the grease.

  • Alexey

    Good afternoon, at 35mm Nikkor (I use Nikon D3200) with a short shutter speed of 400 1000 4000 and ISO 100 and 1.8 strong noises, I tried to shoot just closing the lens with a cover by itself, too, noisy noises, but this is not on the same Helios or Jupiter, only now At 35 and 18 55 Nikor I would like to know, is this such a feature? Noise reduction is turned on, it doesn’t look like hot pixels, while noise is only at short shutter speeds, as I understand it, this is possibly due to the fact that a small amount of light gets in for so short a time, or what is it? Thanks in advance)

  • Lyubochka Mikhey

    I can’t set back the auto iso back, writes eta funky is not valid for this parameter. I have Nikon D 3000. What to do, help please!

  • Valery

    The article mentions the working ISO. How to find out which working ISO on a particular camera? For example, I have Nikon D300s.

    • Arkady Shapoval

      This is a subjective factor, determined by the personal feeling of the noise level at high ISO, you can use the DXO service

  • Oleg

    Good day, dear Arkady. I conducted an interesting experiment the other day: I shot it in different conditions with a change in ISO from 100 to 6400. I got very strange results! It was cloudy during the day and an increase in ISO in aperture priority mode gave an almost linear decrease in shutter speed. Indoors, under artificial lighting, changing the ISO had virtually no effect on shutter speed! Attention question! Is this due to the curvature of my hands, or is there a catch in something else?
    PS Nikon D5100 18-55VR, without flash, I turned off the noise improvers

    • Arkady Shapoval

      In poor lighting conditions, when raised, the shutter speed varies slightly from 1 \ 30 to 1 \ 80, as it should be.

  • Irina

    Photocache. Filmed with a "soap box". Presented by Nikon D3100. About ISO - change it in the camera settings? Do you need to change the settings every time depending on the time of day and weather?

    • Arkady Shapoval

      In the ideal case, this is necessary, but you can install auto ISO, this function will do everything for you.

  • Dmitriy

    Quote: "So, at 1 / 60s, F2.8, ISO 100, the camera will receive the same amount of light as at 1 / 30s, F2.8, ISO 50 or 1 / 60s, F5.8, ISO 800." Probably in the latter case, the sensitivity should be raised 4 times (ISO 400), because the diaphragm is reduced by 2 times.

    • Arkady Shapoval

      Thank you for your attention.

  • Razor

    And in what cases should you turn on the noise reduction function?

    • Arkady Shapoval

      In cases at high ISO when image detail is not important.

Add a comment

Copyright © Radojuva.com. Blog author - Photographer in Kiev Arkady Shapoval. 2009-2023

English-version of this article https://radojuva.com/en/2012/01/what-is-iso/comment-page-1/

Versión en español de este artículo https://radojuva.com/es/2012/01/what-is-iso/comment-page-1/