How to Understand Camera Exposure
Posted on October 17 2017
Most cameras (and phones!) these days are good enough to take great, professional-grade pictures, provided you use the right settings.
Move to Manual for More Control
Lighting is one of the single-most important factors in photography, and learning how to control exposure is key to mastering the art. Here is a basic introduction to exposure to help you take the first step:
Exposure is made up of three, separate concepts (also known as the “Exposure Triangle”)—aperture, shutter speed, and ISO—which determine the amount of data received from light in terms of amount, time, and intensity. It is necessary to carefully balance the three to achieve optimal results. Generally, an underexposed photograph will tend to have “muddy” shadows, compared to an overexposed one, which will have overpowering whites and more washed out subjects and backgrounds.
- Aperture—the size of a hole in the lens controlling how much light enters the camera, measured in f-stops, or the “focal ratio”
A larger f-stop value will indicate a smaller aperture and therefore less light. A high f-stop like f/22 means that the aperture hole is quite small, and a low f-stop like f/3.5 means that the aperture is wide open. For example, if the image below is still too dark, choose a lower f-stop value, which will open the aperture to let in more light.
Aperture is also controls the depth of field, which can help you get focused subjects with blurry backgrounds, or a “bokeh” effect.
- Shutter Speed—the speed at which a shutter closes to determine the duration light is allowed to shine into a lens
The longer the shutter allows light to shine onto the image sensor, the brighter the picture will be; shooting in darker environments will benefit from a longer shutter speed.
Shutter speed also helps with blurriness. For example, if you are taking images of children who won’t stay still for even a moment, increasing the shutter speed (and decreasing the duration) will remove blur at the expense of some lighting. Make sure to take pictures of fast-moving subjects in brighter environments.
- ISO – the level of sensitivity to light
A higher ISO—1600, for example—will produce brighter images than at a lower ISO of 100. Unfortunately, increased sensitivity has its downsides, and the higher your ISO, the greater the level of noise and graininess.
The good news is that phone and camera companies are constantly improving the ability of cameras to use high ISOs without as much grain. All cameras are different, so start out with a few test shots at different times of the day to see how high of an ISO you can shoot at without compromising image quality. For example, the image below is in need of a lower ISO, larger aperture, and decreased shutter speed.
Once you have switched over your settings on your camera from auto to manual mode, you can begin testing out the different settings to see how these three exposure settings produce a perfect image. Grab a subject and try these tips before heading out to buy new gear!