When it comes to the amount of light in your photographs, you’ve probably seen or heard the term “exposure value” or “EV.” But what is EV in photography?
This guide will explain the definition of EV, or exposure value, and go into detail about why it’s important to the photos you take.
What is EV?
In photography, exposure is the amount of light that enters your camera’s sensor. Exposure value (EV) is a number that represents a combination of your shutter speed and aperture as calculated by a formula.
The formula is:
In the formula above, N= your f/number and t=shutter speed.
But, don’t worry, you won’t need to do complicated math equations to learn about EV and why it’s important. Luckily, in the days of modern photography, we no longer need to do these calculations.
That said, the information is valuable for every photographer to understand.
If you’re familiar with the exposure triangle, and the settings of ISO, aperture, and shutter speed, then you won’t be surprised to learn that there are many different combinations of these settings that have the same EV because many different combinations can produce the same exposure.
For example, the settings below both produce the same exposure in terms of light (although, the depth of field and motion blur may be very different), so their exposure value (EV) is the same, 14 EV.
- ISO100, f/8, 1/250th;
- ISO100, f/11, 1/125th.
An EV chart is a table that shows the different shutter speeds, apertures, and their corresponding EV values:
The EV Scale
EV charts are usually shown in ranges from about -6 to +17 or so. That said, there is no limit to the EV scale. Just remember that the higher the EV number, the brighter your scene.
Here are some examples of possible EVs for different scenarios:
- Outside, natural light, snow, or sand: 16 EV;
- Outside, natural light, golden hour: 12 EV;
- Outside, neon lights at night: 10 EV;
- Inside, artificial light, gallery: 8 EV;
- Inside, Christmas tree lights: 5 EV;
- Outside, buildings at night: 3 EV;
- Outside, natural light, at night, full moon: -2 EV;
- Outside, natural light, at night, quarter moon: -6 EV.
Each time you increase or decrease your EV by one value, you are increasing or decreasing by one “stop” of light. In other words, you are capturing half (or twice) as much light as the value before. An EV of 1 captures twice as much light as an EV of 2.
When is EV useful?
EV can be a tricky concept for photographers to grasp. You can properly expose an image without having any idea what your exposure value is.
In fact, why would you take the time to calculate an EV when you have a modern camera that will figure all that out for you?
Unless you’re a film photographer who doesn’t have a meter handy, you probably won’t refer to EV regularly. That said, having knowledge of the concept will make you a better, more well-rounded photographer. But, there are a few real-world applications for EV.
If you’re going to shoot long exposure photography, it’s a good idea to keep a copy of our EV chart in your camera bag.
That way, if you’re using a 10-stop ND filter, you can quickly check the chart for potential aperture and shutter speed values to start with since some meters won’t work properly through the very dark filter.
When you’re learning the very basics of photography, it’s also helpful to refer to the EV chart as another way to double-check that your own exposure settings are reasonable.
While knowing how to calculate exposure values may not be necessary for today’s digital age of photography, EV is deeply tied to concepts you will use every time you pick up your camera, like shutter speed, aperture, ISO, and exposure, so awareness of it only makes you a better photographer.
Those who are interested in long exposures or HDR photography are wise to learn the ins and outs of exposure values and exposure compensation to master their craft.