large image

Trusted Reviews is supported by its audience. If you purchase through links on our site, we may earn a commission. Learn more.

What is ISO on a camera?

ISO is one of the most important settings on a camera, determining the difference between a sharp, high-quality shot and one riddled with noise. 

If you’ve just bought your first camera or are in the market for one, you’ve probably come across the term ISO. But, what is it and how does it affect your photos? 

Read on to learn everything you need to know about ISO on a camera. 

What is ISO on a camera? 

ISO refers to a camera’s film or sensor’s sensitivity to light. The lower the ISO value is, the less sensitive it is to light, while the higher that number is, the more sensitive it is to light. 

Different cameras will have different ISO ranges, but they typically start around 100 and are multiplied by two as they increase. For example, your camera might support ISO 100, 200, 400, 800, 1600, 3200 and so forth. 

However, there are exceptions to this rule, with ISO values often falling in between these multiples (ISO 125) and ranging from as low as 50 to as high as 102,400 on higher-end models. 

The acronym ISO itself stands for “International Standards Organization”, the organisation responsible for developing and publishing technological standards. 

How does ISO affect an image? 

ISO is one part of the exposure triangle in photography, meaning that, along with aperture and shutter speed, it determines the look and quality of your images. 

Increasing the ISO enhances your camera’s sensitivity to light, which helps brighten up your image in dark conditions, such as indoor and outdoor shoots with poor lighting. Unfortunately, doing so also affects the image quality, increasing the amount of noise you can see in the photo. The higher the ISO value, the more grainy and washed out your image might appear. 

This is why it’s better to ensure your subject or environment is well-lit than to rely on choosing the highest ISO values. ISO 100 to 300 is generally a safe range for producing high-quality images in bright conditions, such as daylight and under studio lights. 

Of course, there are reasons you might need to bump the ISO up even in broad daylight.

Going back to that exposure triangle, if you want a fast shutter speed to capture moving objects or a small aperture to sharpen up the background, performing either of these actions will darken your image. To counteract them, you might find yourself needing to up the ISO to prevent the photo from being underexposed. 

How much ISO do I need on a camera? 

How much ISO you need will depend on the camera you buy. 

For cheaper cameras, you’ll likely want to stick with lower ISO values. However, many more high-end, full-frame models are capable of capturing images at higher ISO settings with little grain these days.

The best way to get an idea of what ISO levels a camera can handle is to try the camera yourself or to read one of our reviews, such as the ones in our best camera list.

Why trust our journalism?

Founded in 2004, Trusted Reviews exists to give our readers thorough, unbiased and independent advice on what to buy.

Today, we have millions of users a month from around the world, and assess more than 1,000 products a year.

author icon

Editorial independence

Editorial independence means being able to give an unbiased verdict about a product or company, with the avoidance of conflicts of interest. To ensure this is possible, every member of the editorial staff follows a clear code of conduct.

author icon

Professional conduct

We also expect our journalists to follow clear ethical standards in their work. Our staff members must strive for honesty and accuracy in everything they do. We follow the IPSO Editors’ code of practice to underpin these standards.