Lesson 5: Photography

ISO

ISO refers to how sensitive your sensor is to light. A low ISO number (such as 100) means that your camera is not very sensitive to light. A high ISO number (such as 3200) means that your camera is very sensitive to light. A higher ISO therefore leads to a lighter picture. However, there is a trade-off. A higher ISO number also leads to a grainier image. You would therefore want to use a lower ISO number in situations that you can get away with this. You can do this in case it is bright and sunny outside and when you can use a tripod and are shooting inanimate objects.

Generally, you would use a higher ISO when you take photos in spaces that do not have a lot of light, like when you are shooting pictures indoors or at night. If you would take a photograph with a low ISO in these instances, you will end up with a darker image. You may also want to use a higher ISO if you do not have a tripod and you want to prevent motion blur, especially when you choose to zoom in on your subject or when your subject moves. When you use a higher ISO (meaning that your sensor will be more sensitive to light), you can also use a faster shutter speed to prevent motion blur from occurring.

 

Aperture, shutter speed, and ISO are therefore connected. For example, when you choose a higher ISO, and your sensor is more sensitive to light, you are able to get away with the use of a higher f-number and faster shutter speed. Similarly, if you use a lower f-number (bigger aperture opening), you can use a faster shutter speed, and/or a lower ISO to get the same exposure in your image.