Who remembers loading film cameras with different ‘speed’ ISO film? Having a certain ISO film meant that you could only shoot from the type of film that you have in a camera.
In digital ISO still means the same, but it is much easier to adjust and navigate the different levels. Allow us to teach you a better understanding of how ISO and why it’s so vital to a camera.
ISO is an indication of how sensitive your camera’s sensor is to light. Meaning that the higher the number the more sensitive to light. As a photography major the easiest way for me to remember that was writing a little cheat sheet to keep with my camera bag that said, “ISO 100 is for bright sunny days, ISO 400 is for overcast, ISO 6400 is for dark indoors”. It helped me remember the sensitivity. In the image below you can see how you can reduce or increase light without changing any other setting than your ISO.
The problem with higher ISO is that you images will take on what is called noise or grain. It is the cameras solution to taking on very little available light. You can reduce the grain by lowering the ISO, but if it comes between getting the shot and having grain you should go for that option.
We wouldn’t recommend auto ISO. The more control you have in manually directing your camera settings the better your results and quality of images produced.
Please note that the ISO, shutter speed, and aperture are a triangle of different settings that all play a factor in properly adjusting your camera. However we will discuss those settings later on, one by one.
I hope this simplified understanding what ISO is and the importance it plays in great photography!