Understanding how to achieve a correctly exposed photograph is one of the fundamental necessities of photography. Fortunately, understanding how to accomplish this is not a complicated lesson to learn. The exposure triangle is a concept that will help you grasp how cameras exposure settings interact together to achieve a balanced exposure. What You Need To Know About The Exposure Triangle
1. What Is The Exposure Triangle?
The exposure triangle (or exposure value) determines the amount of light exposed to the film or camera sensor. The exposure triangle consists of 3 elements:
- Shutter speed
To achieve a correctly exposed photograph, all 3 of these elements must work in harmony with one another. In most cases, a correctly exposed image will have an EV rating of 0 in the cameras metering mode.
When one of these settings is changed, another or both must be changed to regain balance.
2. The 3 Elements Of The Exposure Triangle
2.1. Shutter Speed
This element refers to the length of time a camera’s shutter remains open. Shutter speed is expressed as a unit of time and will increase or decrease in halves. For example, a setting of 1/250 means the camera’s shutter will remain open for 250th of the second. One stop below 1/250 is 1/125, and one stop above 1/250 is 1/500. Either half or double the amount of time of 1/250.
A high shutter speed setting is crucial to freeze subjects in motion. However, in low light conditions, it can be challenging to achieve a high shutter speed. This is because the film or sensor must be exposed to more light to create a correct exposure.
The aperture refers to the amount of light that is allowed to enter the camera. This setting is controlled by a system of blades inside the lens. Which creates a circle that can be made wider or narrower. The size of this opening is measured in f-stops.
The larger the f-stop f16, the narrower the aperture and the less light it permits to enter the camera. Alternatively, the smaller the f-stop f5.6, the wider the circle will be. Allowing more light to enter the camera.
Aperture also has a direct relation to the depth of field. In other words, the amount of blurring or bokeh in the image. When shooting landscape photography, the f-stop of a camera will always be high to create tac-sharp images. Whereas in portraiture, a low f-stop will be used to isolate a subject against a blurry background.
The international organisation of standardisation or ISO refers to the level of sensitivity the film or sensor has to light. This setting is expressed as a number.
It is significant to note the difference between ISO in film and digital photography. In film photography, the film has a predetermined ISO. Whereas, in digital photography, it is possible to set the ISO for each individual image.
The higher the ISO, the more sensitive to light the photograph will be. However, increasing the ISO will also increase the level of noise in an image. For this reason, it is best to shoot in the lowest possible ISO settings attainable for a scene.
3. How To Use The Exposure Triangle
To fully comprehend the exposure triangle, one must grasp the fundamental concept of light stops. A light stop is simply a measurement of light. Each time a stop is adjusted, the camera doubles or halves the amount of light it exposes to the film or sensor.
For example, when a cameras shutter speed is halved from 1/125 to 1/60, it reduces the amount of light exposed to the film or sensor by half. Also, by increasing the ISO from 200 to 400, the camera doubles the amount of light exposed. The aperture doesn’t relate to a decisive measurement. However, it is still measured by stops that can be used with ISO and shutter speed to achieve a balanced exposure.
The purpose of the exposure triangle is to always maintain balance (unless one wishes to achieve creative effects such as motion blur). A simple explanation is that if the camera has an EV measurement of 0 (meaning a balanced exposure), and the shutter speed is increased 2 stops from 1/60 to 1/250, then 2 other stops must be adjusted to rebalance the triangle.
These adjustments can be made in either the ISO, aperture or both. If adjusting only one setting, a correction of two stops must be made. On the other hand, altering one stop from both the ISO and Aperture could also be made to regain balance.
In this instance, the camera’s shutter speed has been increased. This means there is less light being exposed to the sensor. To overcome this imbalance the aperture could be opened by two f-stops, which will allow more light to enter through the lens. Or the f-stop could be decreased by one stop, and the ISO raised by one.
Hopefully, this explanation of the exposure triangle has given you a better understanding of the relationships shared by the ISO, aperture, and shutter speed settings.
As always, there is no better substitute in photography than to practice. After reading this article, it is advisable to take your camera and place it on a tripod or flat surface and switch it into manual mode. Once you have achieved a balanced EV of 0, start adjusting the exposure and regain the EV balance by altering the other settings.
Don’t worry if it does not make sense straight away. Like all things, it will come in time and with practice. Be patient, and before long, the camera settings will become second nature to you, and you will start achieving some spectacular results.
What You Need To Know About The Exposure Triangle, What You Need To Know About The Exposure Triangle