The Three Pillars of Photography
Whether you’re shooting underwater or in air, there are three factors that play a central role when it comes to exposure and the resulting image: aperture, shutter speed, and ISO. The three settings are linked and changing one affects the others.
In photography, the exposure triangle explains the relationship between shutter speed, ISO and aperture.
Aperture
Like the iris of your eye, the aperture on the lens of a camera controls how much light is let in. The amount of light that reaches your camera’s image sensor will determine what the exposure looks like. Aperture controls depth of field. The larger the opening, the smaller the aperture number and the lower the depth of field.
Shutter Speed
Shutter speed determines how long a camera lens is exposed to light. Shutter speed is measured in fractions of a second. The lower the number, the faster the shutter speed. A faster shutter speed has the effect of freezing motion, while a slower shutter speed may have some motion blur.
ISO
Adjusting ISO is a way to brighten your photo if you can’t use a longer shutter speed or a wider aperture. A lower ISO number represents a darker image, where a higher ISO number represents a brighter image. When increasing ISO, there will be more noise or grain and less detail within your images or video.