What is ETTR? #
Exposing To The Right (ETTR) is a technique used in digital photography to maximize the amount of information captured in the image, especially the highlights. The goal is to deliberately overexpose the image using aperture and shutter speed so that the histogram of the image data is shifted to the right, toward the brighter end of the histogram. This technique leverages the fact that 50% of the tonal range of an image is within the brightest stop of exposure.
“Correct” exposure in digital photography is slightly overexposed without blowing out the highlights.
Why Does It Work? #
ETTR, takes advantage of the camera sensor’s ability to capture the most tones (levels of brightness) in the brightest stop of a camera’s dynamic range.
If a camera has a dynamic range of 6 stops spanning 4096 levels of brightness; the brightest stop has a full 2048 levels of brightness, half of the total levels just within that one stop. The next stop darker has half that, 1024 levels. By the time you get to the darkest shadows, there are only 64 levels of brightness to work with, which isn’t much. In addition, with each stop lower exposure the levels of noise increase which is why you want to avoid lightening the shadows in post (Lightroom or Photoshop) as much as possible. Doing so amplifies the noise, making it more obvious.
How To Use It? #
Simply put, try to put as much of your image as possible into the brightest stop, the “Sweet Spot,” without blowing out the highlights. Here’s how…
- Shoot in Camera RAW
- Use the lowest ISO on your camera.
- Set your camera to manual. Or you can use the exposure compensation dial for this if shooting in another mode.
- Set up your camera to display the histogram after every shot. OR have it display the histogram continuously depending on what’s available for your camera.
- Take a shot at the recommended meter reading.
- For the average image, the histogram will have a high peak in the middle tapering toward the ends. Increase your exposure so the majority of the histogram falls to the right half of the range without blowing the highlights which will show up as a spike on the far right of the histogram. If you see that spike you’ve gone too far and need to back off a little.
When NOT To ETTR #
ETTR doesn’t work in all situations, however. There are cases in which it’s impractical or the benefits do not outweigh the negatives.
- Depth Of Field/Motion Blur: There are times when increasing the exposure will prevent you from getting the desired effect. Example: If you have an exposure that freezes motion and has a limited depth of field, increasing exposure may introduce motion blur and may make the DOF too small.
- Time Constraints: When shooting sports or weddings where a safer exposure captures the key moment is most important.
- High ISO settings cancel out the benefits from ETTR.
- Dark Subject Matter: If an image is intended to be exceptionally dark overexposing the image may result in color shifts or banding when darkening the image in Lightroom or Photoshop.
