Photography Basics : ISO in Photography

ISO is one of the three main foundations of photography, and in this article we will explore what it is, how to set the ISO, the impact of ISO on your images, and see some examples to illustrate the use of ISO in different scenarios.

What is ISO

ISO stands for International Standards Organization and in photography it’s a feature which brightens or darkens your photo. The higher the value, the brighter the image will be and the lower the darker it becomes.

ISO numbers 

The ISO values in camera can vary from 100 to 25600. The starting ISO value of 100 is what’s called the base ISO. 

Base ISO

It’s quite strange that only the lowest value of ISO has a dedicated name and not the highest value. But one of the main advantages of using the base ISO is that it gives the cleanest photos with no noise. The more you increase the ISO the more you add the noise in it. I personally prefer not going beyond ISO of 800, unless I find myself into a situation where the light is very low. In these cases, full frame cameras perform well even around 1600 of ISO.

What is the impact of ISO on your images

As I said before, the ISO number you choose will impact the quality of your images but also it impacts the brightness of the picture. 

Another impact is the effect of ISO on the dynamic range of the camera, the lower the value the accurate the colors and the higher you go with the ISO the colors become muted and in your images.

This doesn’t mean higher ISO is bad, even noisy photos with grains can be in some situations an artistic choice and give great results.

How to set ISO on your camera

You can set your ISO by using manual setting (M) or Program mode (P). In the Program mode, the camera sets the aperture and shutter speed automatically but lets you control the ISO setting.

For manual mode, everything is set by you, so you can play with it the way you want. 

Ideal use of ISO and examples

Lets see some results of different settings of ISO and their effect on the images

ISO 100,200: When it’s a bright day and sunny, you would like to use this setting as it is the base ISO with no noise and no need for more ISO value. The rule is simple, if natural light is abundant, don’t compromise on the ISO. Another case is if you have a tripod and want to shoot long exposure photo, in this case light is no longer an issue since you can use a long exposure time to capture the light.  

ISO 400, 640: When there is a good amount of light but not so bright, like on grey cloudy days in the afternoon or indoors with some other natural source of light. 

ISO 800, 1000: Usually shoot at 800 when there is less light indoor and using a flash. 

ISO 1600 and more: When you are shooting indoors with less light and not using a flash, you would need more ISO especially. Don’t worry much about ISO 1600 or even slightly above since modern DSLR now handle better these values than before. 


ISO settings
Different ISO settings


When it comes to understanding ISO and its use, you need to consider the other exposure factors which are aperture and shutter speed. Sometimes you don’t want to compromise on the aperture and shutter speed for example shooting landscape photography.

If you are shooting for example a landscape of trees with some wind and you want to freeze the movements of leaves and at the same time have as much of the picture in focus the last thing left to change is the ISO, it’s at this moment you shouldn’t fear to adjust some more ISO, you are no stuck on the lowest ISO, be free to experiment something new, something unconventional.

Happy shooting!