The most important thing about ISO in a camera and what it affects! Capturing an image in a digital camera

Hello! Today I am happy to share useful information about such an important camera function asISO.Many amateur photographers mistakenly underestimate the full potential of this parameter, but in vain. Let's figure out why it is so important to consciously select the necessary camera sensitivity for each specific situation.and how to do it quickly.

The influence of the ISO parameter on the photo

What is ISO?

ISO - this is the photosensitivity of the matrix to photons of light. The higher the value set, the greater the sensitivity. There is one small difference here from film cameras, where each valueISOmeans the film's light sensitivity is doubled. Modern digital DSLRs implement a flexible approach that allows you to change this parameter in even more granular steps.

When selecting the appropriate valueISOThere is one important and at the same time paradoxical point. You should always try to use lowest sensitivity values. Especially when post-processing of photographs is expected. Otherwise, the risk of obtaining “noisy” images, similar in appearance to film “grain”, increases.

It is clear that in creative photography, a high-quality photo does not always mean a good one. Many photographers sometimes even add artificial grain and other scuff marks to enhance the visual effect. But let's talk for now about the technical features of the camera, without going into the intricacies of photography.

Which light sensitivity is better?

What is the paradox of this moment? The fact is that a lot of SLR cameras start their countdown fromISO 200 (for example, up to ISO6400). However, all cameras have digital increase and decrease in sensitivity. So we can lower this parameter in some cameras even toISO50 and increase to exorbitantISO 128,000 and above.

ISO value 3200

Regarding the increase, I think everything is clear and without unnecessary comments. But few people know that digital reduction also degrades picture quality. In simple photo language, detail decreases in “shadows” and “highlights”. It is difficult to say anything definite about which light sensitivity is better, except to advise you to always try to shoot at the lowest possible ISO.

However, I recommend loweringISO up to 100 (even though the camera is designed for values ​​from 200)only in those situations when you are shooting, for example, in very bright sunlight and you want to open the aperture as much as possible. Or in the case of using a long shutter speed, for example, photographing a bubbling stream. But about how to use camera shutter speed 100% - in another article.

Why is there noise?

If you are new to digital photography, you are probably interested in knowing why noise appears and whether it occurs on professional DSLRs. I will try to answer this question as well. And we read about how to choose your first camera.

Camera matrix

Let's start with the fact that, with increasingISOon camera matrix more voltage is supplied. Since all the photocells of the sensor are located quite densely, the increasing electromagnetic fields and rising temperature at each pixel have a great influence, creating inevitable interference on neighboring ones.

This also happens in professional SLR cameras, but the range of “working”ISOmuch wider. For comparison, pictures taken with an amateur camera onISOover 800 is, one might say, a marriage. Full frame Cameras, due to their larger matrix sizes (about 1.5 times), allow you to take photographs of acceptable quality up toISO3200. But despite this, the rule is “shoot at lowISO“It is advisable to observe here as well.

When should you raise your ISO?

Increasing the camera's light sensitivity Allows you to shoot in darker rooms without using a flash. Theoretically, just by increasing or decreasing the valueISOYou can use the same shutter speed and aperture settings both outdoors and indoors. In practice, it is necessary to achieve a reasonable compromise, making the most of all the camera's capabilities. More about settings excerpts and is described in separate articles on my website.

No flash, ISO 1250

At flash photography indoors, a situation often arises where the foreground is lit quite well, but the background, where there was not enough light from the flash, is “failed.” In this case, it is better to sacrifice a little the crystal clarity of the image in favor of its overall visual appeal.

What are we doing? We “raise” the light sensitivity of the matrix toISO400-800 or even higher. The parameters will be different each time and are determined experimentally, or, as my physics teacher used to say, “by scientific poking.” But don't be alarmed that the background will be a little noisy, it's still better than the underexposed version. There will be noise, but at an acceptable level.

Determine for yourself the most acceptable valuesISOwho will be workers specifically for your camera.

This is rather a fact that you just need to come to terms with - the greatest amount of noise manifests itself in shadow parts of the image.

To clean photos, use plugins for photoshop. They give better results than the built-in noise reduction. But avoid excessive “washing out” - everything is good in moderation.

For different purposes completely different values ​​may be acceptableISO(for example, photographs for a b/w newspaper or a magazine spread will have different requirements).

When shooting a report in difficult lighting and without flash, use the auto- ISO. In this case, you pre-specify the range from minimum to maximum in which the function will work. I’m not advocating taking photos completely in “auto” mode, but sometimes there’s simply no time to adjust the camera settings.

Remember that photo quality is subjective. For one, even the slightest noise will be a defect, while the other adds grain himself in Photoshop. Don’t chase perfect quality always and everywhere, focus on your taste, which develops over time, and gain experience.

ISO is often also called ISO sensitivity, ISO level, or simply photosensitivity of the matrix or film.

Still, what is ISO in the camera settings?

ISO- this is a parameter indicating the level sensitivity to light of its light-catching element(matrices or films). They mainly indicate ISO limits for cameras (photo cameras). Although, this same parameter can be found not only on the camera, but, for example, on the flash. For flash, the guide number is usually indicated when using one of ISO 100 or 200. ISO sensitivity indicated in special ISO units. The ISO numeric expression itself can take any integer expression from 1 to infinity. For example, my flash can set ISO from 1 (units) to 12,500, and my camera can set ISO from 200 to 1,600.

Less is better!

The higher the ISO value, the more light-sensitive the sensor. It is very important to understand that the higher the ISO value, the less time it takes for the sensor or film to scan the image from the lens. For clarity, I will give an example: we are shooting in the evening, there is little light, the camera is set to ISO 100, and the camera in priority (or in any other mode) shows that the picture will be taken at 1/20s. This is very long, and at the same time we can get a blurry frame. Because, to reduce shutter speed you need to increase the ISO. For example, we increased the ISO to 800, then it will decrease by 8 times and become 1/160s (one hundred and sixtieth of a second). If it were not for noise, then you could always shoot at high ISO and never worry about the shutter speed; due to noise, you need to lower the ISO and increase the shutter speed and, in addition, worry about not getting a blurry shot.

Raise, close, reduce!

Super high and super low ISO

Many cameras have extended ISO range- usually this is a software increase in ISO, and they are designated as Hi1, Hi2, etc. For example, for a camera HI1 is equivalent to ISO 3200, and on a camera HI1 is equivalent to ISO 6400. Always remember that when shooting at such extended ISO values ​​almost always There will be a very strong picture noise effect. I strongly discourage shooting in the extended high ISO range on any camera. Also, the range can expand to a smaller extent, so the camera has values ​​as equivalents for ISO 100, 160, 130. What benefits does expansion to the low ISO range provide in my article ISO. Some cameras, in fact, do not have a hardware implementation of ISO, I came to this conclusion after conducting.

Which ISO should you choose your camera with?

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 extremely high ISOs, since often they simply will not provide normal image quality. Because professional photographers have concept of working ISO. Working ISO refers to the maximum ISO value at which the camera can produce acceptable results. The trick is that, unlike and , which give completely identical values ​​on all cameras, 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 a camera you can take pictures of acceptable quality at ISO 3200, while in ISO 3200 (Hi1) mode you no longer get a photograph, but complete nonsense. The difference in ISO noise is very noticeable on digital point-and-shoot cameras, where already at ISO 400 the digital noise is often very visible, but at the same time on SLR cameras ISO 400 is quite workable.

What affects noise at high ISOs?

The noise level at high ISO is greatly influenced by camera. The larger the matrix, the less noise. Considering that the matrix in compact cameras is very small, it produces a huge noise level. It can be explained very simply in terms of pixel size. A large sensor has large pixels that can absorb much more light and thus make a strong electrical signal. It is logical that 12MP from a point-and-shoot camera and 12MP from a camera will produce different levels of noise at high ISOs. More information in my article makes a difference.

How is ISO measured?

ISO as well as shutter speed and aperture are accepted count in one's footsteps, for example, 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 is exactly 16 times, or 4 stops. It’s very bad that cameras generally only allow you to change ISO by a stop. So, it is possible to manually set ISO only 200, 400, 800, 1600, HI1 and you cannot set intermediate values ​​such as ISO 250, 320, 500, etc. On more advanced cameras you can set intermediate values, but still fine There is practically no ISO control in any camera. The most interesting thing is that in automatic ISO mode, ISO sensitivity can take any value, such as 110, 230, 1400, etc.

Auto ISO

Example of auto ISO operation

We decided to photograph the cat at home under dim lamp lighting. We have a 60mm lens, to avoid hand tremors, you need to shoot at a shutter speed no longer than 1/60, so we’ll set the maximum shutter speed in the automatic ISO parameters to 1/60, as well as the maximum allowable ISO 800 in order to get maximum image quality. When taking photographs, 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, then the camera will automatically lengthen the shutter speed and lower the ISO and will do this until it hits the specified limit of 1/60 of a second, in which case we will get the maximum allowable shutter speed and the minimum possible ISO for photographing a cat. If there is enough light, then the camera will set ISO 100 (or any minimum acceptable) and any desired shutter speed no longer than 1/60. If there is catastrophically little light, then the camera will set the highest possible ISO and forcibly increase the shutter speed for the correct one. Actually, I I strongly recommend experimenting with automatic ISO in priority mode, since the operation of automatic ISO is quite specific.

Little trick

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

Another little trick

On a number of digital SLR cameras in 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 use the selector to set the desired ISO value, for example 800. And then, with a maximum set ISO of 1600, you get a working range of ISO 800-1600 at which the camera will work - a very, very useful thing.

The Golden Rule of ISO Settings

Always remember the golden rule - you need to shoot at the lowest possible ISO. As soon as you have the opportunity to lower your ISO, do it. Raise ISO only when necessary, for example when the shutter speed at a 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 a high ISO. Although, sometimes you can shoot with flash at high ISO values ​​(details).

conclusions

Meaning ISO directly responsible for photosensitivity and noise level. The higher the ISO, the more noise and worse the photo. The lower ISO- the better the photo, but also the longer the shutter speed.

Have a question? You can ask in the comments. Thank you for your attention. Arkady Shapoval.

ISO or light sensitivity level is a value that determines the sensitivity of film or digital camera sensor to light. Its designation can be found on a roll of film or in the settings of a digital camera.

So what is hidden behind these letters: ISO? In fact, ISO is an acronym that stands for International Standards Organization, and the ISO value, along with shutter speed and aperture value, are the three main factors that ultimately determine the exposure of the frame you shoot.

The ISO value, which ranges from 25 to 6400 (or more), indicates a specific light sensitivity. The lower the value, the less sensitive the film or camera sensor is to light. Conversely, a higher ISO value indicates higher sensitivity to light, which indicates that the film or camera is suitable for shooting in low light conditions.

ISO sensitivity and image noise

In the days of photographic film, low ISO settings also meant that the concentration of light-sensitive salt crystals on the surface of the film was very high, resulting in smoother, cleaner images. The higher the ISO, the larger the salt crystals on the film became, resulting in rougher, grainier images.

In modern digital photography, the same principle applies: the lower the ISO value, the lower the sensitivity of the camera sensor and, therefore, the smoother the resulting image, since the level of digital noise is lower.

The higher the ISO value (higher the light sensitivity), the more effort the sensor must make to obtain a high-quality image, since it will need to deal with a large amount of digital noise (the well-known multi-colored specks in shadows and midtones).

So what is digital noise? This is any light signal that is not generated by the subject and therefore creates a random color in the image.

Modern digital camera designers have developed sensors that produce excellent images at the lowest ISO settings. Most digital cameras have a minimum ISO sensitivity threshold of 100, although some high-end and professional cameras are capable of shooting at ISO 50 and even ISO 25.

There's one more thing you might want to know about image grain. In non-digital photography, many photographers have found creative ways to use grain in an image to give an image a distinctive tone and mood. Unfortunately, digital noise has a different nature - it appears as chaotic clusters of colored dots - and its artistic use is unlikely. However, some photographers have found creative ways to use digital noise.

ISO Sensitivity and Motion Blur

Shooting at low ISOs produces high-quality, aesthetically pleasing images with accurate color reproduction, but it requires ideal lighting conditions.

However, there are some things you want to photograph in low light conditions. Or you might want, for example, a hummingbird, a galloping horse or a moving carousel. In both situations, to capture similar subjects with acceptable exposure, you will need higher ISO settings.

Unlike a film camera, with a digital camera you can change the ISO sensitivity with just one button press, this flexibility allows you to get the image you want much easier.

So, with a high ISO, you can use faster shutter speeds to eliminate blur and/or camera shake. If you want to use creative image blur, then by simply lowering the ISO sensitivity, you can reduce the shutter speed (to values ​​​​less than 1/30 sec), thereby blurring the image of moving objects, while reducing the amount of noise to a minimum.

ISO sensitivity and camera sensor size

The size of the digital camera sensor directly determines how low the noise level will be at certain ISO parameters.

It should be understood that sensor size is not the same as the number of megapixels. The sensor size is its actual physical dimensions. For most of the history of digital photography, digital camera sensors were smaller than the frame size of 35mm film. On digital point-and-shoot cameras the sensor was very small (and continues to be so), and on most digital SLRs the sensor size was equal to the frame size of APC film (23x15 mm).

Smaller sensors produce much more noise at high ISOs (800 and above), mainly because the high number of pixels packed into a small area produces more grain at all but the lowest ISO settings.

Many DSLR camera manufacturers now produce sensors that are the same size as the frame size of 35mm film (called Full Frame).

The larger the sensor size, the more pixels can be placed on it without sacrificing image quality, up to ISO 1600 (for some cameras). On a full-frame sensor, larger pixels are individually more sensitive to light, so the electrical energy required to simulate ISO 800 does not create the same amount of noise as with smaller sensors. Therefore, full-frame cameras are capable of capturing dynamic and dramatic images without a lot of digital noise, even in low-light conditions.

ISO sensitivity and image quality

It is important to remember that the lower the ISO value, the better the image quality will be.

Most digital cameras have an "Auto ISO" setting by default, which reduces your control over image quality because the camera may automatically set a higher ISO, resulting in a lot of noise, while a lower ISO will result in more noise. set manually could give a better image.

Increasing ISO affects image quality in two main ways:

• the contrast of small image details decreases;
• When enlarging an image or printing it, or converting it to JPEG (which has a higher compression ratio), high levels of digital noise can make the photo look muddy and unsightly.

As we wrote above, the lower the ISO value, the better, smoother, and more aesthetically pleasing your images will be.

ISO values ​​between 100 and 200 will give you the best results. And if the size of your camera’s sensor allows, then your photos will remain as such up to ISO 400, while maintaining the possibility of large-size printing (from 20x24 and above).

Conclusion

When shooting any image, it's important to consider the camera's sensor's light sensitivity (ISO), because the lower the ISO, the smoother, less noise-free image you'll get.

It is also important to take into account the light sensitivity of the sensor when preparing for shooting. For example, in order to shoot at the lowest possible ISO, you may need additional light sources.

So when you're faced with unfavorable lighting conditions (i.e. low light or high contrast lighting) or need to use a faster shutter speed, you'll want to sacrifice the image smoothness available at low ISOs and shoot at a higher ISO.

In other words, it's better to increase your ISO and deal with the consequences than not take the photo.

To get the highest quality pictures that a camera can allow, you need to understand such a concept as ISO sensitivity. The article is intended for beginner photographers, so we will try to consider this topic clearly and simply.

ISO sensitivity - what is it?

Back in the days of film photography, someone will remember how film was selected for shooting indoors and for shooting outdoors. The main selection criterion was the film's photosensitivity. Film sensitivity 200 Suitable for shooting outdoors in good lighting. But for the apartment I needed film with a sensitivity of 400.

In simple terms, ISO- This camera sensitivity level to light. The lower the ISO value, the less sensitive the camera is to light, and the higher the ISO value, the more sensitive the camera is. The sensor (that is, the camera itself) is responsible for changing the sensitivity of the camera. camera matrix). This is the most important and expensive part in the camera, which collects light and turns it into an image. At high ISO we can capture images in low light conditions without using a flash. But, depending on the camera level, we get noises(grain in image).

For clarity, look at the image below:

Consequently, noise is very noticeable at high values.

ISO values ​​in modern cameras: 50 , 100 , 125 , 160 , 200 , 250, 320 , 400 , 500, 640, 800 , 1000, 1250, 1600 , 2000, 2500, 3200 , 4000, 5000, 6400 , 8000, 10000, 12800, 16000, 20000, 25600

Impact of ISO on Exposure

We have already discussed how aperture and shutter speed affect exposure in previous articles. Now, in order to understand how ISO sensitivity affects the exposure, consider photographs taken with the same aperture and shutter speed, the lighting did not change during shooting.

f 1/8 1/320 ISO 100 shot indoors during the day

By increasing the ISO value we help the camera sensor capture more light. With each higher ISO setting, the image becomes brighter.

Impact of ISO on Image Quality

As mentioned above, the higher the ISO value, the more noise and artifacts there are in the photo. Also, detail is reduced and colors become duller. In converters you can always smooth out the noise carefully, but the quality will still remain at a low level.

ISO Values ​​for Various Shootings

The ISO setting is usually the first thing we need to adjust in the camera as soon as we are about to shoot something.

ISO 50-200 Suitable for shooting outdoors during the day. Of course, you can bet more, but don’t forget about the quality.

f 2/8 1/500 ISO 200

ISO 400-800 It’s more suitable for shooting in a well-lit room, or outdoors in sunset lighting.

f 1/8 1/500 ISO 400

ISO 800-1600 for shooting in a dark room where it is not possible to use a flash

f 1/8 1/100 ISO 1600

ISO 3200 and above is suitable for shooting the starry sky or the milky way

What to consider when setting ISO

1. Pay attention to the light, whether it is enough or not.
2. Are you going to use flash or not?
3. Will there be shooting from a tripod?
4. Is it acceptable in the photo? digital noise.
5. The scene will be dynamic or static.

Conclusion

Try to always shoot at the lowest ISO settings. Open your aperture as far as your depth of field allows. If you use flash, don't set it too high. ISO, average 800 more than enough.

And most importantly, experiment more!

Hello dear readers of my site! Today we’ll talk about such an important parameter as ISO and how this parameter affects noise?

Previously, when digital cameras were not so popular, under ISO understood film speed. The photographer had to constantly have several types in stock: a more photosensitive one for indoor shooting, another for sunny sketches. Many frames were lost, since after removing the film from the camera it was no longer possible to resnap them.

Now everything is simple, instead of photographic film in a SLR camera, we have a digital matrix. I wrote more about it in previous articles. However, it is not correct to talk about ISO as the photosensitivity of the camera matrix. The sensitivity of the matrix is ​​constant, as is its ! But its sensitivity to light depends on the signal amplification by the camera electronics and software processing.

The sensitivity of photographic film and the camera matrix are not the same thing!

In the digital camera settings, the ISO value can be set manually. For example, it is allowed to be set in the range from 100 to 3200. There are 2 more super ISO values ​​- Hi1 and Hi2, but the noise level at them is off scale.

How to work with ISO?

From the photo above it is quite clear that if there is not enough light in the photo, then set the ISO higher and vice versa, if everything is overexposed, then lower. True, there is an important nuance: it will not be possible to painlessly increase the “photosensitivity” of the matrix, so we read the article to the end.

Let's look at the effect of the ISO parameter using an example

I did a little experiment. The green car was photographed from a tripod under equal conditions in aperture priority mode. Consequently, after I set the ISO value, the shutter speed was automatically set. We look carefully at the image below to see how the amount of noise changes.

It’s easy to notice that there is much less noise in a photograph with ISO 100 than in others, especially than in Hi2, so we try to photograph at low parameter values. But this is not always possible. For example, at parties, performances, or night shooting, you have to set a higher “light sensitivity” parameter of the matrix in order for at least something to be visible in the photograph.

Why does noise appear in the image?

A digital matrix is ​​a complex circuit consisting of photodiodes and other electronic components, therefore, as the useful signal is amplified, image defects also increase. So, the better the engineers of camera companies take care of the algorithms for processing the ISO parameter, the better the quality of the pictures will be, but also the cost SLR camera will grow. Moreover, the wider the range of possible values, the easier it is for the photographer to play with the settings during the shooting process.

In practice, it can be cost effective to use higher ISO values. For example, when photographing with an external flash, you can increase the “photo sensitivity of the matrix” value, but at the same time reduce the flash power. With these settings, the service life of the flash lamp in the flash increases, because it works in a more gentle mode, and a change in ISO from 100 to 400 is not always noticeable to the eye.

If you have any questions or disagree with something, please leave your comment.