ISO is a camera setting that controls the brightness or darkness of your photos. It is a crucial setting to use properly if you want to take the best possible images. There are questions to ask when deciding what ISO to use:
1. What time of day are you shooting? If you are shooting outside during the middle of the day, you will need to use a lower ISO such as 100 or 200. If you are shooting at night without a tripod, you will have to increase the ISO to a higher number to be able to record the light on the camera’s sensor.
2. Will the subject be well lit? If your subject or scene is too dark you will need to use a higher ISO such as 800 or 1600.
3. Do you want a sharp image or an image with more movement in it? Using a high shutter speed to capture fast movement might mean that you need to use a high ISO to compensate. Likewise, if you’re using a slow shutter speed to capture blur you will need a low ISO to compensate.
Don’t forget, increasing your ISO increases the grain or pixel size in your photo. So don’t use an ISO of 3200 or 6400 if you don’t want a photo with a lot of digital noise or film grain.