In photography, what is 'ISO'

Written by Daily Fix - Published 15-Jun-2023, last updated 21-Jun-2024

ISO is one of the three main exposure controls in photography, along with aperture and shutter speed. It is a measure of the sensitivity of a camera's sensor to light. A higher ISO setting will make the sensor more sensitive to light, resulting in a brighter image. A lower ISO setting will make the sensor less sensitive to light, resulting in a darker image.

ISO is measured in numbers, with a higher number indicating a higher sensitivity. The most common ISO settings are 100, 200, 400, 800, 1600, and 3200. However, some cameras can go even lower or higher than that.

The term ISO originated back in the days of camera film. ISO originally referred to the sensitivity of film, or it's 'light gathering' ability. The higher the ISO rating, the higher it's sensitivity to light and the greater the film's ability to capture images taken in low light.

High ISO film was called 'fast film', it required a shorter exposure than a low ISO film. For digital photography, ISO refers to the sensitivity of the camera's sensor.

What impact does ISO have on a photograph

The ISO setting is an important tool for photographers to control the exposure and noise level of their images. By adjusting the ISO setting, photographers can create images that are properly exposed and have a low noise level.

So the ISO setting has two main effects on an image:

Exposure

ISO affects the exposure of an image. A higher ISO setting will make the image brighter, while a lower ISO setting will make the image darker.

Noise

ISO can also affect the noise level in an image. Noise is a type of visual distortion that appears as random specks of color or tone. A higher ISO setting will typically result in more noise in an image.

How to use ISO in photopgraphy

To use ISO in photography, you will need to adjust the ISO setting on your camera. This setting is usually located on the top of the camera or in the camera's menu system. The ISO setting is usually represented by a number, such as 100, 200, 400, 800, 1600, or 3200.

To change the ISO setting, you will need to turn the ISO dial on your camera, or use the menu system on your camera. The ISO dial will usually have a series of numbers marked on it, so you can easily see which setting you are currently using.

Once you have changed the ISO setting, you will need to take a test shot to see how it affects the image. You can then adjust the ISO setting as needed until you are happy with the look of the image.

When should I use a lower ISO setting on my camera?

One scenario when you should consider using a lower ISO setting on your camera when you have enough light available. This is because a lower ISO setting will produce images with less noise, which is a grainy texture that can make your photos look less sharp.

Other situations when you might use a lower ISO setting include:

• Bright light conditions: When you're taking photos outdoors on a sunny day, there is plenty of natural light available. This means that you can use a lower ISO setting to get a good exposure without introducing noise.
• Landscape photography: Landscape photography is often done in bright light conditions, so using a lower ISO setting is a good way to get sharp, noise-free photos.
• Photographing static subjects: If you're photographing a static subject, you can use a lower ISO setting and a slow shutter speed to get a sharp photo without introducing noise.
• Post-processing: If you're planning to edit your photos in post-processing, you can use a lower ISO setting to give yourself more flexibility to adjust the exposure and contrast without introducing noise.

It's important to note that using a lower ISO setting may require you to use a slower shutter speed or a wider aperture. This can be problematic if you're hand-holding the camera, as it can lead to camera shake or blurry photos. If you need to use a slower shutter speed or a wider aperture, it's important to use a tripod to keep your camera steady.

Tips when using a lower ISO setting

Here are some tips for using a lower ISO setting:

• Use a tripod: If you're using a slow shutter speed or a wide aperture, it's important to use a tripod to keep your camera steady. This will help to prevent blurry photos.
• Use a faster shutter speed: If you can't use a tripod, you can use a faster shutter speed to reduce camera shake. However, a faster shutter speed may not be possible if you're hand-holding the camera in low light conditions.
• Use a narrower aperture: A narrower aperture will let in less light, which can help you reduce the ISO setting. However, a narrower aperture will also reduce the depth of field, so be careful not to lose your subject in the background.

The best way to learn how to use a lower ISO setting is to experiment with different settings in different situations. See what works best for you and your camera.

When should I use a higher ISO setting on my camera?

You can use a higher ISO setting on your camera when you need to take a photo in low light conditions. This is because a higher ISO setting will allow you to use a faster shutter speed or a narrower aperture, which will help to reduce camera shake and blur.

Here are some examples of situations where you might want to use a higher ISO setting:

• Night photography: When you're taking photos at night, there is very little natural light available. This means that you'll need to use a higher ISO setting to get a good exposure.
• Indoor photography: If you're taking photos indoors, the lighting is often not as bright as it is outdoors. This means that you may need to use a higher ISO setting to get a good exposure.
• Photographing fast-moving subjects: If you're photographing a fast-moving subject, you'll need to use a fast shutter speed to freeze the action. This may require you to use a higher ISO setting.
• Using a telephoto lens: Telephoto lenses magnify the subject, which can make it more difficult to hand-hold the camera without getting camera shake. Using a higher ISO setting can help to reduce camera shake in these situations.

It's important to note that using a higher ISO setting can also increase the amount of noise in your photos. Noise is a grainy texture that can make your photos look less sharp. The higher the ISO setting, the more noise you'll typically see.

Ultimately, the best way to decide whether or not to use a higher ISO setting is to experiment and see what works best for you in each situation.

Some tips on using ISO

Here are some tips for using ISO in photography:

Use a low ISO setting when possible to reduce noise in your images.

Use a high ISO setting when you need to make a photo brighter, such as in low-light conditions.

Experiment with different ISO settings to see how they affect the look of your images.

Use the ISO setting to control the exposure and noise level of your images.

Conclusion

ISO is a powerful tool that can be used to control the exposure and noise level of your images. By understanding how ISO works and how to use it, you can create images that are properly exposed and have a low noise level.

So get out with your camera and start experimenting with different ISO settings!