Aperture, ISO, Sutter Speed: Which Settings Do You Change in Manual Mode?

One of the biggest questions that I get is how do you know what settings to change when you're using manual mode on your DSLR. Aperture, shutter speed and ISO all change the amount of light that your sensor will capture, but they all have secondary effects as well. It's these secondary effects that will determine which setting you will need to change to get the photograph that you want.

Aperture is the setting that controls depth of field. If you know you want a certain amount of depth of field for a certain image, set your aperture first.

Shutter speed is the setting that controls motion and subject freezing. If you need a certain shutter speed to either freeze or blur your subject, change your shutter speed first.

ISO is the setting that determines how much noise or digital grain there will be in an image. ISO is that last think that you'll want to change. It will be the setting that will allow you to use the aperture and shutter speed that you want. You'll want to keep your ISO as low as possible to get a clean image.