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This post was most recently updated on November 7th, 2021

If you are new to photography, or a beginner looking to learn new skills and techniques, then this guide is for you. We have got all the information that you need to become a photography pro! 

This particular guide is all about ISO, what it means, what it stands for and why you need to consider it when setting up your shots.

Most photographers will tell you as soon as you start that there are three essential elements or pillars of photography that you have to be aware of when taking pictures. These are the aperture, the shutter speed and the ISO. 

So, what is ISO, and how does it affect your images? Let’s find out! 

What Does ISO Stand For?

ISO is actually an acronym for International Organization for Standardization. This is an organization that makes many different technological measurements and product standards that are used across the globe. 

What Does ISO Stand For In Photography (Understanding ISO For Beginners)

ISO was first used to refer to film speeds for film photography, and was the number given to represent the sensitivity of certain film emulsions to light.

There were two types of standard films called ASA and DIN, which were added to ISO standards during the 70s, and from then they have been referred to as ISO as a general term. 

These ISO numbers were given to rolls of film to convey how sensitive they were to light. The lower the number, the less sensitive it was to light, and the higher the number, the more sensitive. 

Whilst ISO originally was meant to be about film’s sensitivity to light, it has become synonymous with digital cameras too, with manufacturers using this term to maintain the brightness levels in your photographs, in the same way you would have to for film photography. So, what exactly is ISO?

What Is ISO?

In the most simplest terms, ISO is a setting on your camera that will affect how bright or dark the images appear. As you increase the ISO number, the images will become slightly brighter, as you change the settings higher and higher, which can be very helpful if you are shooting in low light conditions.

Raising the ISO therefore can help you capture things in the dark in greater detail that you would not normally be able to.

But, there is a catch. By increasing the ISO number, you are increasing the chance of the image having a lot of grain on it, or noise, which decreases the quality of the image overall. 

With too much grain, your image may not be clear enough, or of a good enough quality, so you have to be careful when using ISO. The good news is that you don’t just have to use ISO to brighten your image.

Instead, you may alter the aperture and shutter speed of your image, and use those in conjunction with the ISO to get better photographs of a higher quality. 

Using ISO With Aperture And Shutter Speed

You will want to get the most out of your photographs, but you will need to use multiple camera settings to do so. As mentioned above, you can use ISO to brighten your images, but you will not want to have noise or a grainy look on your photographs. 

This is why in some conditions, you will need to use ISO in addition to aperture and shutter speed settings. For instance, if you are shooting wildlife, then you will need to use fast shutter speeds, as animals move quickly, and you will not want motion blur on your images.  

The only problem is that when shooting wildlife outdoors, you rely on natural lighting, and sometimes you may be shooting during a sunset. This may not give you sufficient exposure for your images.

Now, you could have more light by slowing the shutter speed, but this will introduce blur. 

So, what can you do? Well, you can alter your aperture to control the light that reaches the sensor, and change the ISO setting to brighten the image. This way, you can keep your fast shutter speed, and still have a clear, bright enough image. 

What Are The Common ISO Settings?

Most digital cameras will have the same common ISO settings that you can use. These are shown below from low ISO to high ISO values:

  • ISO 100
  • ISO 200
  • ISO 400
  • ISO 800
  • ISO 1600
  • ISO 3200
  • ISO 6400

As you can see, the values double each time. Therefore, if you double your ISO speed, then you will effectively double the amount of brightness in your image.

What this means is that an image taken with ISO 400 will be twice as bright as the same image taken with ISO 200. 

To help you understand how this setting works, we recommend that you pick a subject and focus your camera on it. Take a photograph of the subject with the ISO set to ISO100.

Then, take another photo of the same subject, in the same manner, but with ISO 200 set. Do this with all of the options on your camera to see for yourself how each setting affects the image overall. 

What Does Base ISO Mean?

Your camera will have a basic, standard ISO setting called ‘base ISO’. This is the setting that will give you the highest quality of photo, without any grain or noise at all if possible.

Most modern digital or DSLR cameras will have a base ISO of ISO 100, which is the lowest.

When taking your photographs, you should always aim to stay at the base ISO if possible so that you can get the best quality image possible. However, you will have to alter the ISO if you shoot in darker or low light conditions. 

What Does ISO Stand For In Photography (Understanding ISO For Beginners)

How Do I Change ISO?

If you want to learn how to change the ISO setting on your camera, then we suggest that you look at the instruction manual that came with the camera.

This will give you detailed and in depth guidance on how to do it. All cameras have different settings and ways to alter them, so this is the easiest way to find out.

That being said, some DSLR cameras can have similar ways of altering the ISO.

The simplest way to do this is to change your camera over to a Manual mode instead of Auto. You can also change the ISO in Aperture Priority mode, or Shutter Priority mode. 

Then, to change it you may have to head to the menu on your camera and search for ISO.

Other DSLR cameras may have a specific ISO button on the back of the camera. For instance, on most Canon DSLR cameras, the ISO can be selected by pressing the arrow up button above the SET button. 

Once you click on the ISO menu, you will be able to choose from the list from ISO 100 to usually about ISO 3200, and then set it. 

Tip: Which ISO To Use

If you’re unsure which setting will be best, then you need to understand when to use a lower ISO and when to use a higher ISO setting. Always stick to the lowest ISO if you can, as long as you have plenty of light. 

Even if you are in low light settings, you can use a lower ISO if your camera is mounted, and use a longer shutter speed to give you more light instead.

Alternatively, you can use a high ISO to avoid motion blur from lower shutter speeds, and to increase the light for the camera.