ISO

ISO is the same as ASA, it describes the sensitivity of your 'film' or in our case, how sensitive the chip in your camera is to light.

You can change the ISO by pressing the ISO button and scrolling the wheel or pressing direction arrows, looking in your menu or check your manual.

• The more sensitive your camera is to light, the faster shutterspeeds you can use, to get pictures of moving objects without blurring them.

• However, the higher the ISO, the poorer quality the image will be. Noise, the digital version of film grain, increases as the ISO gets higher.

So you need to change your ISO to control blur and to control quality.

Below is a table of the showing how changing your ISO affects your shutterspeed. 

Don't forget to return your ISO to auto or a middle setting!

References: here, here, here and here :)