Why is ISO Important in Photography?

ISO is important to understand in photography but many beginner photographers don’t really get it.

Choosing the best ISO setting will help you get better photos. If you have your ISO set incorrectly your photos might not look how you want them to.

ISO stands for “International Standards Organization.” So knowing the ISO definition does not help you know the function of ISO in photography.

The ISO sensitivity setting controls how responsive the camera’s sensor is to light. The lower ISO, the less responsive the sensor is. When you are changing ISO to a higher setting then your sensor becomes more responsive.

This international standard is used on all cameras. It’s the same on your phone and in the top professional camera on the market.

If you set the ISO sensitivity on your camera too high your photos will not look so good. With a lower setting you are better off.

A high ISO setting can cause digital noise. Digital noise in photos is random visual distortion of the pixels in a photo. Technically, digital noise is a lower signal-to-noise ratio in your photos. The amount of noise you may consider acceptable can be different from what others might accept.

The higher the ISO, the more digital noise appears in photos. It’s more noticeable in dark areas of compositions.

Some people refer to this as grain, but it is not the same as grain in film. Film grain has a different look and feel to it. Each type of film has a different grain structure and can be used creatively by skilled photographers. I have never seen an attractive use of digital noise in a photo.

Other problems caused when the ISO sensitivity is too high are flat colors and contrast.

It’s a good practice to keep the ISO as low as possible.

Changing ISO sensitivity to the lowest setting helps you create more technically pleasing images. At lower ISO settings you will not have a problem with noise or flat color or contrast.

Each camera sensor manages ISO differently. You can use higher ISO sensitivity settings on some cameras than others. This varies from camera to camera and brand to brand.

More expensive cameras are more capable of producing high-quality photos with higher ISO settings. Digital noise on phones and compact cameras is usually much worse than on professional level DSLR and mirrorless cameras.

Some photographers don’t worry too much about ISO sensitivity and digital noise. They are content to ‘fix’ their photos on the computer. I prefer to capture images with the highest possible technical quality. So choosing the lowest ISO setting best.

Changing ISO sensitivity settings is necessary when the light is low. And when your other exposure settings have reached their practical limits.

In low light you can open your aperture to let more light into the camera. You can also use a slow shutter speed. But these two settings will sometimes not be enough to capture a well-exposed photo.

If your aperture is as wide as possible and your shutter speed is as slow as practical, then it’s time to change the ISO sensitivity.

You may have reasons you don’t want to use your widest aperture or slowest shutter speed. This is also when changing ISO sensitivity settings is the best option.

In a setting with good light you might want to use a narrow aperture to keep a lot of your composition in focus. This is a good time to raise your ISO setting. Wanting to keep your shutter speed fast enough to freeze action is another instance when you’ll want to set a higher ISO.

You may have reasons you don’t want to use your widest aperture or slowest shutter speed. This is also when changing ISO sensitivity settings is the best option.

In a setting with good light you might want to use a narrow aperture to keep a lot of your composition in focus. This is a good time to raise your ISO setting. Wanting to keep your shutter speed fast enough to freeze action is another instance when you’ll want to set a higher ISO.

Yes. Reducing digital noise is possible with the right software and some knowledge of how to use it.

Many software programs like Lightroom and Photoshop can reduce high levels of digital noise. You must be careful not to overuse these tools otherwise you can run into more problems.

Removing noise can soften the look of a photo when it’s overdone. Some people then try to sharpen the image to compensate and this can end up making it look far worse.

Having your camera set to save RAW files you’ll get better results when you reduce the noise using computer software. RAW files contain all the data the camera captures, to they are better to manipulate. If you save photos as jpeg files in your camera, the image is smaller and lower quality. This type of image file does not respond so well to manipulation.

Keep you ISO as low as possible. This will give your photos the best technical quality.

When you need to retain a fast shutter speed or use a narrow aperture setting, using a higher ISO setting is a good option.