What is the exposure triangle

Exposure is one of the first areas of photography where new photographers can start building a strong foundation. Once you master the exposure triangle, you'll have complete control over how bright your images look, how fast your subjects move, and how clear your images appear. And by mastering the exposure triangle, you'll know exactly how to adjust the different variables in almost every type of lighting to achieve the perfect shot.

Exposure is defined as the interplay between three basic camera options that influence both how much light enters your camera's sensor and, ultimately, how your finished photograph looks. Those three basic camera options include aperture, shutter speed, and ISO. While each option influences exposure individually, none of them operate independently

For example, if you increase the light entering your camera via one option, then you typically need to decrease the light entering via one or both of the other options to ensure your photograph remains looking like you want it to. Learning how to create a proper balance of all three is the difference between a photographer who shoots manually with confidence and one who relies solely on the camera to decide for them.

Aperture defines the hole within your lens that allows light to enter the camera sensor. As with anything else related to exposure, a larger hole allows more light into your camera, and a smaller hole allows less light into your camera. Aperture is defined using f-stops. While initially confusing, f-stop values essentially define whether a large hole (lower f-stop value), such as f/1.8, is being created, allowing more light in, versus a small hole (higher f-stop value), such as f/16, allowing less light in.

A shutter speed determines how long the camera sensor is exposed to light during each shot taken. Shutter speeds can be expressed in terms of fractions of a second or in whole seconds for longer shutter speeds. Fast shutter speeds (such as 1/500th of a second) create extremely brief periods of time in which light can reach the sensor, freezing movement in images. These types of shutter speeds are useful for capturing sports, wildlife, and action-type photography.

Conversely, slower shutter speeds (such as 2 seconds) will keep the sensor illuminated for longer periods, creating motion blur. Motion blur can be creatively applied to display flowing waterfalls, moving car trails at night, or silky smooth water flows over rock formations. Slow shutter speeds help allow more light into the camera sensor for nighttime photography (especially with stationary subjects); however, a tripod must be used to prevent unintended camera shake.

ISO represents how sensitive your camera sensor is to light. Low ISO values (such as ISO 100) require more light to produce a well-exposed image but will deliver a clean, detailed image with virtually no digital noise. High ISO values (such as ISO 32000) allow your sensor to become more sensitive, enabling you to take an acceptable image under low-light conditions but at the expense of increased digital noise throughout your image, appearing as specks or grains. Photographers weigh ISO against available light and limitations imposed by aperture and shutter speed. Under bright daylight conditions, low ISO provides clean images. In low-light venues where faster shutter speeds and/or larger apertures cannot be employed, increasing ISO is usually the only alternative to maintain proper exposure.

Achieving true mastery of exposure involves finding a balance between all three elements - aperture, shutter speed, and ISO. None of these factors work independently; changing one factor will impact the other two. If you intend to use a shutter speed that will effectively freeze motion in your subject(s), you'll be reducing the amount of total light available to illuminate your sensor. You might therefore choose to increase Aperture or ISO to compensate

If you wish to employ low ISO levels to create clean images in low-light conditions, you will likely need to opt for wider aperture sizes or slower shutter speeds to admit sufficient light. If you opt for a smaller aperture size to increase depth-of-field in bright sunlight conditions, you may need to opt for faster shutter speeds to avoid overexposing your image. Ultimately, every shooting scenario calls for evaluating trade-offs based upon all three parameters.

When you know how the exposure triangle functions, you'll be able to get a greater degree of creative and technical control over your images than you could ever obtain using any kind of automatic shooting mode. By knowing how aperture, shutter speed, and ISO function, you can:

• Properly expose your images in a wide variety of lighting situations from bright daylight to poorly lit interior spaces
• Freeze fast-moving objects or intentionally add motion blur to give your images a more dynamic feel
• Control the depth of field of your image to separate your primary object(s) from distracting backgrounds.
• Minimize digital noise to produce clean and professional-looking images.
• Have the ability to make intentional creative decisions rather than relying on the whims of the camera.

At this point in your photographic career, you're not going to master exposure, and photography is still something happening to you instead of something you're shaping.

Most new photographers fall prey to some consistent mistakes when learning about exposure:

• Increasing ISO above reasonable levels when you could have achieved acceptable exposure levels employing aperture or shutter speed options.
• Employing shutter speeds that are too slow to support handheld shooting methods results in unwanted blurring caused by camera shake; this error is commonly misidentified as an improper focus setting.
• Selecting an incorrect aperture size for the specific scene, for instance, taking a group photo at f/1.8 when only one individual remains sharp due to the extremely shallow depth-of-field produced by that aperture setting.
• Dependent entirely on auto mode and failing to educate yourself on what decisions the camera makes and why.

As mentioned before, practicing with manual or semi-manual camera modes, reviewing your images, and experimenting deliberately with each element one at a time will serve as the best method for improving your photographic skills.

In summary, the exposure triangle forms the basis upon which all other photographic techniques rest. Once you understand how aperture, shutter speed, and ISO interact with each other, you will possess actual control over your images in ways that automatic shooting modes can never replicate. You will be capable of exposing correctly regardless of how poor the lighting conditions are, controlling motion and depth of field in order to achieve desired aesthetic qualities, and solving problems quickly without hopelessly relying on "luck." It does indeed take practice; however, developing this fundamental aspect of photography knowledge is likely the most valuable thing any photographer can develop relatively early in their career