Few photographers know what exposure value is. However, every photographer faces it constantly dealing with exposure compensation and post processing of RAW-files on computer. You can often hear the phrase “take bracketed shots at -2/0/+2EV” in conversations about HDR. But what is EV? How to calculate it and why do we really need it?
What is Exposure Value?
Exposure is the amount of light that reaches the camera sensor when shooting a single photograph. Factors that affect non-flash exposure are:
- Aperture: how large the opening into the camera is
- Shutter speed: how much time the light is allowed to enter
- ISO: the sensor sensitivity of the camera
Exposure value is the combination of these three issues. Different figures of aperture, shutter speed, and ISO can give one and the same EV value, but the images you take will differ. Your camera measures the scene in EV, than it adjusts the three above factors to make a perfect shot depending on the kind of scene.
Why do You need to Change Exposure Value Settings?
Digital cameras make mistakes despite their cost or how many different features they have. Complicated scenes can make your camera sensor perceive the light in improper ways.
If you quickly take shots without checking and adjusting ev, you will probably have many underexposed or overexposed shots. Photo processing software such as Aurora HDR will help you, but it is sometimes impossible to regain details in light and dark parts of the picture.
You have to follow certain rules when shooting high contrast scenes, especially when you do not have a tripod. Adjusting the EV setting on camera will give you the ability to shoot a white cat in a white background without making it go gray or invisible.
You will also need to set EV exposure to control the depth sharpness depending on what effect you want to reach. What is the scale for EV and how can you calculate this value? Find the answers below.
How to Calculate Exposure Value?
Explore the relation between Exposure Values, f-stops and shutter speed. Have a look at the table for choosing the right value for you. The adjustments you commonly pick up are limited by your digital cameras dynamic range and the case at hand.
What are the examples of adjusting different exposure values?
- Artificial light from ads at night 9 to 10 EV
- Artificial light from fountains or buildings at night 2 to 5 EV
- Natural light at golden hours 12 EV
- Natural light at night -2 to -11 EV
- Snowy or sandy scenes 16 EV
- Clear sunlight scenes 12 EV
- Artificial light in offices, galleries and gyms 8 to 10 EV
- Interior at home or Christmas tree lights 5 EV
How to adjust your camera settings for HDR shots?
High dynamic range of a photograph indicates the difference between the lightest and the darkest parts of the scene. A single-exposure shot on current camera sensors cannot capture both bright and dark details.
Bracketing is the method we use to capture maximum details. It means taking a series of shots at 1 or 2 exposure value stops. If your camera supports auto bracketing mode, you will have to push the shutter once. For everyone who starts to learn what HDR photography is, it's critical to master the process of bracketing.
You can adjust your camera manually to -2/0/+2EV stops for taking one underexposed, one overexposed and one normal set of shots. If you shoot complicated scenes at night or on a bright sunny day, you can take up to ten shots at 1EV stop per each of them. A tripod is a valuable tool to ensure your shots remain level and motion free between each EV exposure.
HDR greatly exceeds the EV you can shoot letting you expand the dynamic range of your digital camera and precisely expose various elements of a photo without having to sacrifice details or artistic quality.
How to merge bracketed shots into a beautiful HDR photo?
Import photos from your camera onto your Mac as you usually do. You will need a specific software for merging bracketed exposures into an HDR image. Aurora HDR is one of the most popular apps, which is also available as a free demo version.
Take few steps and get the job done:
- Launch Aurora HDR and load the brackets;
- Click Create HDR.
The proprietary tone mapping algorithm makes HDR images look natural. You can find available controls for extra editing in the right sidebar. One-click presets change the effect from natural to extreme. Color, tone and contrast controls are available for selective and global editing. Get rid of noise and half-visible objects with corresponding controls.
Save, export or share your results after you finish. Keep in mind that Aurora HDR was made exclusively for Mac users. One click and the job is done.