By Laura | 28th November 2019

A quick beginner’s guide to ISO

If the thought of switching off the auto settings on your camera terrifies you, our handy beginner’s guide to ISO will help you to understand how this key setting affects your images.

Taking control of the exposure triangle of ISO, aperture and shutter speed will make photography more fun and help you to grow your skills... and that means better images!

What is ISO?

Very simply, ISO is a measure of your camera’s sensitivity to light. If you take a photo at f/2.8 and 1/200th with a low ISO number of 100 and another with the same aperture and shutter speed, but an ISO of 800, the second shot will be brighter. This means that for a given aperture, a higher ISO gives you more shutter speed, which limits camera shake and allows you to shoot in darker scenes with more ease.

That sounds simple, right? It is, but there are other factors to consider before you turn that ISO dial up!

Noise and image quality

You might be thinking that it makes sense to leave the ISO set high to make capturing sharp images easier, but there’s a trade-off. As your ISO goes up you start to introduce noise into your pictures and reduce dynamic range. Noise (or grain, if you ever shoot with film) is a gritty effect that affects image quality by reducing sharpness and altering the natural colours and contrast of your pictures –bad news if you want the best quality photos!

Finding the sweet spot

Any beginner’s guide to ISO should aim to help you to figure out how high your camera can go before it produces poor quality images. Unfortunately, it’s not as simple as suggesting a single setting because it depends on many factors. How sharp was the original image? What was the light quality? How big are you viewing the shot? Will it be printed? What camera do you have? All of these factors matter, but the most important one is you. What are you happy with? If you’re a pixel peeper who likes to look at your photos at 100% you’re going to be less forgiving than someone who prints all their photos at 6”x4”.

The simple answer is to experiment. Shoot lots of pictures under lots of conditions and see what you’re happy with. As a basic rule of thumb, aim for the lowest ISO setting that gives you the shutter speed you require for a sharp image. This ensures the best image quality possible.

We hope this simple beginner’s guide to ISO gives you the confidence to play around with your camera and produce some great shots worth printing to canvas and hanging on your wall with pride!


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