The low ISO values ensure the smooth color in this photo. This makes the blurriness in the background and foreground all the more effective. So what exactly is ISO? In short, ISO measures sensitivity to light.
In this tutorial you will learn:
A low ISO value means that the sensor is less sensitive to light.
Using a lower ISO produces clearer, smoother images.
Using a higher ISO can result in grainier, 'noisier' images.
Avoid high ISO values except in low light situations, when a long exposure isn’t possible.
As a rule of thumb, an ISO of less than 800 will produce clear images.