ISO in Photography – What Is Noise and How To Remove It

ISO In Photography – Introduction

ISO in photography refers to the international standard of light sensitivity for photographic film, which has been adapted to digital image sensors. The ISO value determines how sensitive the camera sensor is to light. The higher the ISO value, the greater the sensitivity and the ability to shoot in lower light, but this can also lead to increased noise in the image.

The history of ISO sensitivity dates back to the days of analogue photography, when different types of film had different ‘speeds’, or light sensitivities, expressed in ASA (American Standards Association), which were later replaced by the ISO standard. In digital photography, instead of changing the film, we change the noise setting in the camera, which allows more flexibility and control over the shooting process. The evolution of digital technology has greatly improved the quality of images at high ISO, making it possible to shoot in increasingly difficult lighting conditions.

General Objectives and Importance of Standardisation in the World

The aim of ISO standardisation is to unify and standardise sensor sensitivities across different camera models and brands, allowing photographers to more easily compare settings and results between different devices. This standardisation is crucial for professionals and amateurs alike, enabling them to fine-tune their camera settings to suit the prevailing light conditions and expected image quality.

Understanding ISO Is … Easier Photography 🥸

What Is ISO?

ISO determines the sensitivity of the sensor in a camera to light. The higher the ISO value, the more sensitive the sensor is to light, allowing you to shoot in lower light without having to change the aperture or exposure time. However, higher ISO values can also lead to more noise in the photo, which can affect the overall image quality.

Dependence of ISO on Other Exposure Parameters

ISO, exposure time and aperture form the exposure triangle, which is the basis of all photographic settings. Changing one of these settings requires compensation by the other two to maintain the correct exposure. For example, if you increase the ISO, you can reduce the shutter speed or aperture, which is particularly useful in low light.

Examples of How Different ISO Values Affect Image Quality

ISO 100-200

Provides superior image quality with low noise in an image, ideal for photography in well-lit conditions.

ISO 400-800

Slight increase in noise but still good image quality, useful indoors or on overcast days.

ISO 1600-3200

You get a rather noisy photo, but the ability to shoot in low light without a flash.

ISO 6400 i wyżej

You get very noisy photo that can affect image detail and colour, only used in very low light.

Understanding and using ISO in photography correctly allows you to adapt to different lighting conditions and is essential to achieving the desired exposure and quality of your images. Photographers need to strike a balance between appropriate lighting and acceptable noise levels to get the best possible photo in a given environment.

Low vs. High ISO

Low ISO Photos = Low Noise Photo

Low ISO values, such as 100 or 200, are usually (but not always!) the most desirable in photography due to the fact that they minimise the appearance of noise while maintaining the highest image quality. They are ideal for shots taken in well-lit conditions, outdoors on sunny days or in a studio with adequate lighting. Using a low ISO produces clear, sharp images with rich detail and vibrant colours.

High ISO Photos = High Noise Photo

High ISO values such as 1600, 3200 and even higher are essential when photographing in low light conditions where you cannot or do not want to use flash. They allow you to capture more light, but at the expense of increasing noise in the photo. In practice, photos taken with a high ISO can appear grainy or less sharp. However, modern cameras have increasingly better noise reduction technology, allowing us to use high ISO values more effectively.

How to remove noise in an image?

Techniques for minimising noise

Shooting at high ISO often leads to noise, but there are several techniques that can help minimise this problem:

1. Most modern cameras have built-in noise reduction functions that can be activated when shooting at high ISO. However, it is worth bearing in mind that this can slightly reduce the detail of the image.
2. Photo editing software, such as Adobe Lightroom and Photoshop, offer advanced noise reduction tools to preserve as much of the photo’s detail as possible while reducing the visibility of noise.
3. Photos with the correct exposure usually show less noise than those that are underexposed or overexposed. The ‘exposure to the right’ (ETTR) technique involves slightly overexposing the photo when it is taken and then correcting the exposure in processing, which can effectively reduce noise.

Noise Removal Software

In the past, special applications were used exclusively to remove noise from photos. Nowadays, photo noise is removed with basic image processing. Here are some suggestions

• Adobe Lightroom, which offers comprehensive noise reduction tools that allow the intensity and detail of the reduction to be fine-tuned.
• DxO PureRaw, known for its extremely effective noise reduction, even at very high ISOs, preserving the details of the photo.
• Topaz DeNoise AI, which uses artificial intelligence to identify and remove noise, often giving the best results, especially in challenging conditions.

With the right shooting and processing technique, it is possible to significantly reduce noise while maintaining the relative quality and detail of the images. Today we will do a test using Adobe Lightroom.

And here the settings we used to get the right effect:

ISO in Digital and Analogue Photography

In film photography, ISO (also known as ASA in older systems) refers to the sensitivity of the film to light. A higher value means more sensitivity, but also more grain in the image. Once selected, film with a certain ISO value had to be used until the end of the roll, limiting flexibility.

Find Out More

• Film Camera – Getting Back to the Film Photography

In digital photography, ISO can be adjusted dynamically, without having to change film or sensor. This means more flexibility and the ability to adapt to different lighting conditions on the fly. However, rather than grain, high ISO values in digital photography lead to digital noise, which can affect image quality.

How the Approach to ISO Has Changed

Camera developments have significantly changed the way photographers approach ISO. Cameras have been offering high ISO values with better noise control for many years now, allowing photography in conditions that would have been unattainable with analogue photography, without significantly affecting image quality.

In addition, modern editing software, such as the example shown above of using Lightroom, allows for further noise reduction and improved quality of photos taken at high ISO, which expands photographic possibilities and allows for greater creativity.

3 Practical Tips

Experimenting with ISO requires an understanding of its effect on images and the ability to adapt to changing lighting conditions. This, however, we seem to have got the hang of. Here are some practical tips:

1. Start with a low ISO – always start with as low an ISO as possible to ensure the highest image quality, and then increase the ISO only when necessary to get the correct exposure.
2. Use manual or ISO priority mode – this will give you more control over your settings and allow you to experiment with different ISO values, while maintaining the other exposure parameters.
3. Check images for noise – regularly check images on your camera during a shoot, paying attention to noise levels, especially at higher ISO values.

An example would be a photo shoot in a dimly lit interior. You may want to start at ISO 800 to avoid using flash and keep the lighting natural. If the images are too dark, gradually increase the ISO to 1600, 3200, etc., while monitoring the appearance of noise and loss of detail.

Another example is photographing a landscape in the evening. Setting the ISO to a lower level, such as 100 or 200, using a tripod and a longer exposure time will produce sharp and detailed images without noise, even in low light.

Summary

We’ve covered various aspects of ISO in photography, from basic definitions, to the differences between digital and analogue photography, to practical advice on managing noise and choosing optimal settings. Key points to remember are:

1. ISO is one of the elements of the exposure triangle, alongside aperture and shutter speed, and plays a key role in adapting to different lighting conditions.
2. Higher ISO values allow you to shoot in lower light, but can lead to more noise in your images.
3. Low ISO values provide the best image quality, with minimal noise, but require more light.
4. Today’s image processing technologies and software offer advanced noise reduction capabilities, allowing more flexible use of high ISO values.

Photography is all about practice and experimentation, which is essential for skill development. Test different ISO settings in different lighting situations to understand their effect on your images and find your own preferences.