Exposure refers to the amount of light the camera sensor is exposed to. Understanding how to get a good exposure, and how your camera controls exposure, is the first step to producing a great quality image. Our free Exposure Cheat sheet is a great quick reference when out in the field.
Your camera requires a certain amount of light to be able to capture detail in an image. If there is too little or too much light, the camera will struggle to capture this detail. Think of your eyes, if you are in an extremely dark or an extremely bright room, you will struggle to see. Your camera operates in a similar way when capturing an image.
When you are capturing an image (depending on the amount of light in the scene) you will need to adjust your camera’s exposure settings to either allow more or less light to reach the camera’s sensor. This will result in a brighter or darker image.
Most cameras do this automatically for you in the ‘auto-exposure’ setting. We suggest that you do not use this automatic setting, which will allow you more control in the outcome of your image. Using a setting such as Aperture Priority, Shutter Priority or Manual, will give you that control.
A camera has three different mechanisms to control exposure. Let’s take a look at these briefly.
You can download our helpful Exposure Cheat Sheet to assist you with how each of these mechanisms affect your image when you out in the field.
The aperture is the diaphragm situated in your camera lens that can open and close. This controls the amount of light that enters the lens and onto the sensor. A wider aperture (low f-number) means more light will be let through the lens, simply because the opening is larger. A narrower aperture (high f-number) allows less light through the lend to the sensor.
Aperture affects the exposure and the depth of field (DOF) in an image. DOF can also be called the ‘depth of focus’ in an image. Practically, this is how much of the subject you are focussing on is in focus, and how much of the background / foreground is blurred out.
Wide Aperture f2.8 (shallow DOF)
Narrow Aperture f18 (wide DOF)
Shutter speed refers to the amount of time that your camera shutter opens to expose your sensor to light. Shutter speed is measured in seconds and is usually only a fraction of a second long.
Shutter speed affects the exposure of an image as well as how sharp the image is (frozen in action or blurred).
Fast Shutter speed 1/2000
Slow Shutter speed 1/20
ISO is the light sensitivity of your camera sensor. ISO will affect how long the sensor needs to be exposed to light in different situations. The lower the ISO number, the less sensitive it is to light. A high ISO indicates an increased sensitivity of your camera sensor.
ISO also affects the quality of the image. The higher you push the ISO or light sensitivity of your sensor, the more grain becomes visible in the image and vice versa.
Base ISO setting on most cameras: 100 ISO
High ISO: 4000 ISO (this will change from camera to camera and the quality of the sensor).
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