It has become very apparent that over the last decade that more and more people have started using cameras, precisely, DSLRs. People are no longer satisfied with regular mobile phone images. Everyone is well read and knows what good quality images are.

One of the key aspects of any kind of photography is the ISO. You may have heard it or you may have read it. But, what does ISO mean on a camera? Well, that is what we are going to answer today.

It is quite a task to take those perfect and crisp images without having an actual understanding of what an ISO is and how the ISO works. Any basic photography workshop you go for, the first thing they will teach you is the three pillars of photography, which are the Aperture, the Shutter Speed, and lastly the ISO. All of these three work hand in hand in order to provide a good picture.

In order to be a good photographer, it is crucial that you understand what each of these is and how each of them works individually as well as together. Knowing these three pillars of photography like the back of your hand will ensure that you always deliver fantastic looking photos which you see in magazines and high-end websites.

In the article below, we aim to provide as much information as possible about the ISO. Be sure to completely understand what this is first before moving on to researching the remaining two.

What Does ISO Mean on a Camera? How Necessary is it? 

To know what ISO is, you first need to know what it stands for. The ISO stands for International Standards Organization. This is the norm in the industry for the sensitivity of the emulsion based film.

So, in lay man’s terms, the ISO refers to the level or amount of the sensitivity of the camera that is available to the light. If you have set your ISO number low then there is very little sensitivity to the available light, and if you have set the ISO number very high, then there is a lot of sensitivity to the available light.

What changes the camera’s sensitivity to the light is called the image sensor, or popularly as the sensor.

The sensor is a very important and the most expensive part of the camera. This sensor is what is responsible to gather the necessary light in order to transform it in a picture.

As the sensitivity increases, the camera’s sensor is capable of clicking pictures even in surroundings with less light and that too with no flash. But this comes at a cost, as the sensitivity gets higher it will add noise or grain to the image.


To see in in reality what we are talking about, take your camera and click two exactly identical images with the only difference between them being the ISO. Keep one of them either at 100 or 200 and the ISO for the other image at the highest possible level, perhaps at 3200.

There is one thing you will notice straight away, the image clicked on the lower ISO is very clear, meaning it has less to no noise in the image. While the image clicked with the higher ISO, however brighter, is evidently very grainy and has a ton of noise in it.

Every camera you use has a base ISO. This refers to the lowest level of the ISO that the camera is capable of clicking on.

You will notice that most older DSLRs such as Nikon and Fuji have a base ISO of 200. This has changed today. As the technology has advanced, the base ISO level has gone down too.

You will find that most Nikon and Canon cameras today have a base ISO of 100. However, there are very few cameras on the market that go as low as 80.

It is important to keep in mind that in order to get a high-quality image you must keep your ISO as low as you possibly can. In fact, keeping the ISO at 100 is always an optimum choice.

The way the ISO level increases in cameras are by the numbers multiplying by two. So, if the base ISO is 100, the next would be 200, then it would move on to 400, 800, 1600, 3200, 6400, etc.

This means that the ISO 200 is two times more sensitive than ISO 100. As you figured, ISO 400 is four times more sensitive than ISO 100 and ISO 1600 is 16 times more sensitive than ISO 100.

So, when we say that it is four or 16 times more sensitive means it needs that much less time to click the picture. To elaborate the speed of the ISO:

  • ISO 100 takes a second
  • ISO 200 takes ½ a second
  • ISO 800 take 1/8 of a second
  • ISO 3200 takes 1/30 of a second

When Should You Use a Lower ISO? 

As mentioned earlier, it is always advisable to use your ISO at the lowest level possible. Of course, this would also depend on how much light is available in the surrounding.

If the lighting in the surrounding is dim and you yet want to keep the ISO low, ensure that the camera is placed on a tripod or on a flat stagnant surface. Also, ensure that the subject is not moving as it takes a while to actually capture the image.

When Should You Use a Higher ISO? 

Clicking pictures on a high ISO is only advisable when there is lack of lighting in the surrounding. Images clicked with a flash are very evidently sharp, hence it is better to choose a higher ISO. Another case where it would be preferable to use a high ISO is in times when you are in a need of very fast shots, such as a cheetah running or birds flying. Bear in mind the higher the ISO, the noise level increases too and you should factor that in as you increase it.


We hope this article answers your question on what does ISO mean on a camera. As you see, the ISO plays a very important part when it comes to the lighting of the image.

ISO is very important, but in order to click a perfect image, you also need to learn adequately about the shutter speed and the aperture as they all work in tandem.

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