The Exposure Triangle of Shutter, Aperture, and ISO - Cramer Imaging - Quality Fine Art Photography
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The Exposure Triangle of Shutter, Aperture, and ISO

The Exposure Triangle of Shutter, Aperture, and ISO
When I started studying photography, I had no idea that there were technical aspects to using a camera.  Technical aspects which can be the difference between an OK shot and an amazing photograph.  I quickly learned about manipulating the shutter speed, the aperture, and the ISO for proper image exposure.  Learning these basics has drastically improved my photography.

Graphic image depicting the exposure triangle of photography including the settings of aperture, ISO, and shutter speed by Cramer Imaging

Shutter Speed


Shutter speed is rather easy to define.  It is how long the shutter of the camera is open and allows light into the sensor.  Pushing the shutter button opens up the shutter and it will release as programed to do so.  Short shutter speeds can freeze motion while long shutter speeds can blur moving objects.  Each side has its own merits and uses in photography.

Shutter speed controls how long light is allowed to strike the sensor for.

Aperture


Aperture is best described as the diaphragm of camera.  It can act as a chocking point for how much light gets through to the sensor while the shutter is open.  Wide open apertures let in lots of light and result in a shallow plane of focus (or depth of field).  This mostly means that the background is blurred out of focus.  Tightly closed apertures result in little light making it through to the sensor.  The depth of field is far deeper and lots more of the background will be in focus.

Aperture controls how much light is allowed to strike the sensor.

ISO


ISO is the abbreviation for International Organization for Standardization.  This means little as this organization is responsible for more than camera exposures.  What does this term really mean for my camera?

ISO for modern cameras is the digital version of what used to be film speed.  It also used to be known as ASA (American Standards Association).  Older cameras will display this term instead of ISO.  The film speed describes how light sensitive the original camera film was.  The more sensitive the film, the better the exposure in low light settings.  The less sensitive the film, the better the exposure in bright light situations.

ISO controls how sensitive the sensor is to the light that strikes it.

How They Work Together


Aperture, shutter speed, and ISO act like axes of a graph.  Aperture would be the x-axis, shutter speed is the y-axis, and ISO becomes the z-axis.  Each has a particular setting or value in order to generate a properly exposed photograph.  No graph is complete without all the coordinates and no photograph is complete without all the elements of exposure.

As with coordinates on a graph, if you alter one setting, you alter the entire exposure.

If one particular setting cannot be altered for one reason or another, then the other two settings can change in order to create what is known as equivalent exposures.  One such example of not altering a setting is when shooting photos in florescent light where the shutter speed must be some multiple of 1/60th of a second in order to catch the full spectrum of the light cycle.

When properly attuned, these elements of an exposure can create amazing and powerful images together. Below are examples of what the combinations of shutter speed, aperture, and ISO can yield when properly applied in photography.

Cramer Imaging's professional quality landscape nature photograph of the Teton River Dam canyon in mist near Driggs, Idaho
A small aperture, short shutter speed, and low ISO are suitable for most indoor and outdoor exposures.
Professional quality fine art nature photograph of a dandelion seed puff against green grass in Pocatello, Bannock, Idaho by Cramer Imaging
A wide aperture, short shutter speed, and low ISO result in isolation of a stationary subject from the background in this manner.
Cramer Imaging's professional quality nature photograph of rare astronomical conjunction of planets Venus and Jupiter with Jovian Moons
A wide aperture, long shutter speed, and low ISO are suitable for astrophotography work and the proper exposure of stars.
Quality landscape silky water spring with trees and rocks professionally photographed by Cramer Imaging near Alta, Wyoming
A small aperture, long shutter speed, and low ISO can create smooth water flows such as this.
Cramer Imaging's professional quality nature insect photograph of a resting yellow dragonfly with green background in Pocatello, Bannock, Idaho
A wide aperture, fast shutter speed, and high ISO will stop motion where a flash is not available such as with this windblown dragonfly.
Cramer Imaging's professional quality fine art photograph of a trumpet in low key light in Pocatello, Bannock, Idaho
A wide aperture, long shutter speed, and high ISO would be useful for motion blur, time lapse, or low exposure in a dark room.
Cramer Imaging's professional quality astrophotography photograph featuring the Milky Way at night in Cherry Springs, Caribou National Forest near Pocatello, Bannock, Idaho A small aperture, long shutter speed, and high ISO are useful in astrophotography where you are trying to capture the colors of the Milky Way Galaxy with some foreground interest.

This combination will also work well when trying for star trails with some foreground interest as well. The foreground must be stationary or it will blur with the long exposure.
The combination of small aperture, fast shutter speed, high ISO is a rarity which would be useful in a night club or at a play where the light is dim and no flash is allowed.  I don't have an example photograph of this kind.

Conclusion


A properly exposed photograph has three elements: aperture, shutter speed, and ISO.  These camera settings control how much light is let in, how long it is let in for, and how sensitive the sensor is to the light it receives.  A little attention to this matter will drastically improve your photography as you are starting out.  Once you have mastered these basics, then you are ready for some real fun and exploration in the world of photography.