Learning Manual – ISO

The ISO is formed by International Organisation for Standards. ISO is not an abbreviation, it is a word derived from a Greek word “isos” which means equal. This is one of the elements which helps control Exposure in a photograph (the other 2 being Aperture and Shutter Speed).


In very simple terms, ISO is a feature in your camera that will either brighten your photo or make it dark. With a high ISO number, your photo tends to become brighter and with a low ISO number, your photo will become darker.

Below is a graph which shows the ISO values (numbers).


Apart from this, you will also see “Auto” in your ISO settings (I absolutely love this Auto setting!!) which means that your camera will set the ISO automatically according to the available light conditions. ISO 100 and ISO 200 settings are ideal for broad daylight captures  because the camera, at that point in time, is not sensitive to light, whereas ISO 3200 and ISO 6400 settings are ideal for low light captures because the camera is very sensitive to light.

The difference in the ISO settings (hover around the captures to see the settings) and how it affects the brightness/darkness is made clear by the images below.



Did you notice how beautifully ISO adjusts our captures’ exposure to light? Pretty cool, isn’t it?

Apart from controlling the sensitivity to light, ISO also determines the noise pattern in a capture. You may have noticed a lot of grains/dots in pictures; those grains are known as Noise. You might also come across the word “Grain” a lot if you read more about photography, but as a beginner you can just be aware of these 2 words but there is nothing to get confused. Both these words are used interchangeably.

A high ISO setting in a capture would have a lot of noise (although this can be reduced in post-processing). Too much noise ruins the naturalness and quality of a capture, which is why using a low ISO setting is always recommended. 

Below captures will help you understand the difference between a capture with a lot of Noise and absolutely no Noise.

A nighttime capture with too much Noise
A nighttime capture with no Noise (Shutter Speed 20 seconds, ISO 100, F8)

How do I manage a low light capture with less noise – this is the question in your mind right now!

For this, you have to make changes in the other 2 settings which are Aperture and Shutter Speed. You will have to open your Aperture hole and decrease your Shutter Speed, for which a tripod will be required. Once you learn the basics of ISO, you can get into these details.

Just like Aperture, ISO is also an important feature in the Exposure setting. Through this blog, I’ve tried to simplify this concept as much as I could for all those who wish to pursue Photography as a hobby. Hope this blog has simplified the concept for you.

P.S.: Any thoughts or comments are welcome.

Happy Photographing!