What is an ISO on a camera and how to use it correctly

Many amateur photographers might not know what is an ISO on a camera, well don’t worry you are in the right article for that
ISO is one of the elements of the exposure triangle that enables us to obtain the appropriate lighting for each image, which consists of aperture, shutter speed and ISO.

Read also: What is an ISO or light sensitivity in photography ?

ISO sensitivity is one of the most important camera options. When you are trying to photograph a place in low light and you don’t want to lower the shutter speed so that you won’t get moving pictures, you raise the ISO and then wow, amazing. I solved the problem, but is it really that easy. This is what we will learn today, and now I am still at the beginning of the article. I think that I will not finish writing until after hours, so if you are really interested in professional photography, read the entire article, even if it is long, it is very important to understand the ISO because by putting it on the automatic mode only you will not become a professional photographer Start.

What is ISO sensitivity?

Light is the main flavor in any good photographic recipe, without which the image tastes different, i.e. without good lighting there is no good photo. The ISO sensitivity is something of this type like a value indicating the percentage of light or light that your camera needs to take a photo.

ISO – In the beginning, that is, in classic cameras, it was not possible to control it, but film tapes were sold at a specific ISO, meaning that in the past, if you wanted to change the ISO ratio, you had to change the camera film by another.

The sensitivity of the film was consistent with the ratio of ‘silver halides’, something like the pixel size of our day. And with it, these tapes were made.

Read also: The definition of aperture in photography and how to control it

Today, with digital sensors, silver halides are only history, or at least in digital cameras.

The higher the ISO, the more sensitive the sensor is to light, and vice versa. With this in mind, we can take photos even in low light. The highest ISO ratio varies according to the type of camera and also according to the size of the sensor. In reflex cameras, it often starts at the value 100 and in the Canon 600D cameras that I use the highest value is 6400. The lower the ISO ratio, ie 100, the normal lighting, I always try to use the lowest possible value to avoid the appearance of noise in the image.

How does ISO work?

To understand how the ISO works, we must first understand how the camera sensor works. ISO depends on how the sensor captures light and converts it into a digital file.

The sensor is that small chip that converts the light that reaches it into an image. Like the film in classic cameras, the sensor consists of thousands of sensitive cells that work to convert the light that passes through the lens.

When light passes through, each cell converts it into an electrical current after processing it. The camera brain (the camera’s processor) generates a digital file ‘image’ which is stored on the memory card.

The sensitivity of each cell is fixed and corresponds to the lowest ISO value in the camera that the sensor and processor can process.

So since the ISO value is fixed, how do you change it by touching a button on the camera? In fact, the sensitivity of these cells is not increased since their value is fixed. Rather, the electric current or the signal emitted by these cells is amplified or increased.

If you are shooting a low-light scene, when you strengthen the signal emitted by the sensor cells, you are not only increasing the percentage of light that was able to reach the sensor but rather generating some noise as well. The more you strengthen the signal emitted by the sensor cells, the greater the noise in the image. Here, the noise is generated that all photographers hate.

 In the picture below, you find an example of each ISO ratio, and you will notice that the higher the ratio, the more noise appears and the image’s shape changes:

what is an ISO on a camera
The noise ratio in each ISO value

Sensitivity and noise

It is clear that from the previous interpretation I concluded that a greater ISO equals more noise, especially in darker areas.

There are three situations that can cause noise in your photos:

Signal Booster: This type of noise, as we discussed earlier, results when the cells’ signal is amplified, which converts the light into electrical signals. This is called electrical or electronic noise.

Noisy picture

Temperature: In addition to the signal amplification noise, the sensor temperature also produces noise when we are shooting long exposure, for example the temperature of the sensor rises, which ends up generating the known thermal noise.

Post-production: When you take a picture and get a low-light result, then you try to use the computer to increase the brightness of the image in an image editing program. The computer cannot retrieve the data that the camera could not capture. What will require the computer to add information or data to an image of his invention Generating noise in the image.

The way the noise appears in your photos varies in shape, size, and quantity depending on the reasons that caused it to be generated, including sensor size, camera type, etc. It may be imperceptible or apparent so that in the end the noise can ruin the quality of your photos.

However, noise is not annoying in all cases, if you know how to live with it, that is, please use it and take advantage of it. Because noise does not always ruin the images, many times it gives them strength that increases their beauty. Here, I will give you an example of a picture that I took and it appears some kind of noise in the dark sky, but it did not ruin the image.

Noise doesn’t always ruin photos

How do I avoid noise in my photos?

Placing the -iso-at the lowest possible value: Placing the -iso-at the lowest possible value does not mean placing the -iso-at the lowest value in the camera, but rather the lowest value where the image appears clear. Always make sure to set the shutter speed to the appropriate settings. The slower the shutter speed, the more light you enter, and the greater the aperture of the lens, the greater the percentage of light we get as well. But the settings always remain according to what we want to get and what we want to present in our pictures.

Avoid heat: Avoid sensor heat by taking a break between taking one photo and another, and when using long exposure for a long time, you will not only be able to get noiseless images, but it will also increase the life of your camera.

Correct exposure: The secret to every great photo is proper lighting. In all cameras, there is a bar at the bottom that tells us the amount of brightness Focus on being always in the middle to get the best result.

The importance of correct exposure

The ISO sensitivity is one of the three elements through which we obtain exposure to images, the other two are the aperture and shutter speed. These three form what is known as the exposure triangle.

As you can imagine, in order to maintain a constant ISO (as low as possible) without disturbing the balance of the triangle, you have to make sure that the available light is measured correctly with the ISO, so you have to adjust the shutter speed and aperture you want to get.

Shutter speed allows you to fully convey the feeling of movement in long exposure or scene freeze by increasing shutter speed. The aperture enables us to blur the background or get focused images of landscapes. These two elements, as you may have noticed, are the compositional elements that allow you to add elements to your photos in contrast to the ISO sensitivity that only allows you to capture scenes in low light.

You can get images with lower noise ratio using a higher ISO sensitivity if you perform the correct exposure in your photos, and if you choose a lower ISO sensitivity with incorrect exposure. You will be forced to correct the exposure on the computer, and you will end up adding more noise to the image than if you had used the correct exposure and ISO right from the start.

What sensitivity should I use?

Focus on using the lowest ISO value, but taking into account the difference in lighting from scene to scene, so you have to measure the correct ISO ratio in each scene.

Take the radio as an example while you are using the ISO, you hear a piece of music on the radio and there is a slight noise with the music that you hear, you liked the music and you raised the volume to hear the beautiful clip louder and you find that this has resulted in more noise, so also the ISO. Low with little noise in the image. When you try to turn up the brightness by raising the ISO, the noise level will also increase.

Experience what we have learned

Photography, like everything new we learn, cannot be mastered without experience, so we will try what we learned without touching our camera, but at the bottom there is an application that will enable us to do so, adjust the settings shown until you reach to produce an excellent image at the lowest possible ISO value and you will be able to do this from While adjusting the aperture, shutter speed and ISO, while focusing on the exposure indicator, it appears properly:

I also tried the app, here are the settings that I entered:

what is an ISO on a camera

And this is the result that I got:

what is an ISO on a camera