Photography’s Holy Trinity

leaves on a canopy at a wedding reception

Controlling a camera comes down to three basic settings; aperture, shutter speed, and ISO. These are considered to be the holy trinity of photography. These three settings are all about controlling the amount of light that gets to the sensor of the camera. Let’s look at them one at a time.

1. aperture

Aperture is the opening in the lens of the camera that varies the amount of light that enters. There are blades inside that open to allow in more light, or close to let in less light. This works the same way as the iris, the colored part of your eye does. They both change their size to let in more light or less. Changing your aperture not only controls the amount of light entering your camera, but it also controls the depth of field of the image. This is the aesthetic/visual component. You can read more about this in my post ‘Photography Depth of Field Demystified‘. Aperture is measured on a scale of f – numbers or f -stops. They are both the same thing, just different terms. So you will see f/16 or f/5.6. The smaller the number, the more light that hits the sensor. Aperture is usually referred to by it’s size. So a small aperture means a smaller hole and less light, like f/22. A larger aperture means a bigger opening and more light, like f/2.8.

2. shutter speed

Shutter speed is just what is says. It is the amount of time that the shutter, a protective curtain in front of the sensor, is open. So if aperture is the amount of light flowing in, then the shutter speed is the gate, the controller of how much of that light gets to the sensor. Shutter speeds are commonly shown in fractions of a second, like 1/15 sec. But many photographers just say they shot it at ’15′. It is understood that you are talking about a fraction of a second and not 15 seconds. Some people will say they shot it at a ’15th’. Just make sure if you are writing it down that you use the fraction. So that means as the number gets larger, the shutter speed is faster. For example 1/250 is faster than 1/30. Shutter speed controls whether a subject is frozen or blurred. Using it creatively can lead to all types of interesting effects. Using it wrong can lead to disasters and unusable images. If you are hand holding your camera at lower speeds, like 1/15 sec, you will most likely have camera shake. A safe range is one over the focal length of the lens. So if I am using a 200mm lens, then I should not hand hold the camera below 1/200 sec.

3. iso

ISO, or as it used to be called, film speed, refers to the sensitivity of the camera’s sensor or film. In a digital camera using a higher ISO, higher number, like 800, will keep the sensor turned on longer. In the film days, higher ISO films were more sensitive to light and therefore better in low light combinations. So the higher the ISO number, the more sensitive the sensor and the less light you need to make an exposure. The drawback to using a hight ISO, like 800 and above, is that it generates more noise. In the film world, higher ISO films were always grainier.

Combining these three elements; aperture, shutter speed, and ISO will give you your exposure. There are many combinations of the three that will lead to the same exposure, but how you set each one can greatly effect the look and feel of your final image. I will be talking more about this in the future.

Gary Miller

www.redphotophotography.com

Houston Fine Art Wedding Photographer

Houston Wedding Photographer

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Related posts:

1. Photography Depth of Field Demystified