ETTR summary plus a real example

Last Update: 21 January 2023

Much is said and written about ETTR (Exposing to the Right). Enough to believe most photographers see the value of using ETTR. Unfortunately, this is not the case. The challenge is YouTube talking heads and forum experts continuously promote wild statements, resulting in a powerful technique being lost in a cloud of confusion. See this article for more about modern marketing.

We are looking at an example of using ETTR in this article. If you like to see more information, go to this article. Also, see this article discussing the 2-Step Exposure Technique.

Olympus EM1 II with Leica 25mm f1.4 lens - ISO6400 f7.1 1/13Sec w ETTR - Raw file converted in WorkSpace and edited in Photoshop

Think of ETTR as a process of determining the best possible exposure. We know fast shutter speeds are used for sports photography and large apertures for isolating subjects. Sports photographers prefer good light and/or higher ISOs. We also know an underexposed sensor means more image noise.

The key to top image quality is a Saturated Sensor and

ETTR is one of many exposure techniques.

What is Exposing to the Right (ETTR)?

ETTR is a basic process of adjusting the shutter speed and aperture to ensure more reflected light on the image sensor. The key is the sensor. The ISO setting does not control the reflected light reaching the sensor. We know camera sensors perform best when fully exposed. See this article for an illustration showing the different terminologies like luminance and reflected light.

What is the role of the ISO function?

The ISO function is another variable in the exposure formula used in the camera. It's important to remember the ISO setting does not control the reflected light reaching the image sensor. Use Auto ISO for general use and Manual ISO for critical applications. Use a fixed ISO for challenging applications and the shutter speed and aperture to control the reflected light to the sensor. 

For example, select an appropriate ISO for use with the ambient light in buildings and adjust the shutter speed and aperture to find the correct exposure settings for the sensor. Study this article for more information about the ISO function, shutter speed, and aperture.

The most important technique for improving image quality is to know the ISO. 
Avoid the auto ISO setting and learn how to manually set the ISO.

What are the benefits of ETTR?

When you clear away the talk about photons, pixels, and sensor size, then one fact remains. The average consumer camera is designed to record more tonal data in the highlights. That means the camera captures 2x more tonal data for each +1EV of ETTR. The image signal SNR improves with a more saturated image sensor. Image noise increases with an underexposed sensor.

How does one apply ETTR?

ETTR is not meant for every situation. For example, I often use an Exposure Shift of +0.3EV to increase my average exposure. I prefer Aperture Mode and a fixed ISO of 64 or 100 during the day. I will up my exposure settings with another stop in the late afternoon or blue-hour photography.

Assume you have a critical shot and like to have top image quality. The first step is to manually select the ISO. Use the histogram and increase your exposure with the Aperture and shutter Speed.

Tip:- Keep the ISO fixed

Olympus EM1 II screen

Olympus cameras use an Exposure Headroom of up to 1EV. This is why the histogram is less than optimally exposed in Auto Mode. The exposure meter is linked to the exposure headroom. ETTR helps us to manually bridge this exposure headroom. It is critical to practice with your exposure settings. For example, one can increase the exposure by up to 2EV in a blue sky behind the subject. In other situations, it's only possible to safely increase the exposure with 0.5EV. The camera's exposure meter will show an overexposure with ETTR, and the histogram will simply move to the right.

Study the image below. I upped the exposure with 1EV. There was enough dynamic range headroom available to increase the exposure. This is how much the camera meter underexposed the sensor.

Olympus EM1 II screen

General comments

Photographers are told ETTR is only applicable to the camera's base ISO. This is incorrect because the sensor is designed to capture more tonal data in the highlights, irrespective of the ISO value. Promoters will say the dynamic range decreases at higher ISO values. The solution is to use your histogram, the exposure meter, and other visual features to prevent unwanted clipping.

Tip:- The ISO effectively adjusts image brightness and not exposure.

In terms of exposure, the following is critical:-

• Only the Shutter and Aperture determine the reflected light reaching the sensor
• The ISO function only amplifies the image signal coming from the image sensor

The samples and the info below were taken from the first image in the article:-

Conclusion

Olympus cameras generally underexpose the sensor. This is the main reason for the loss of image details and more shadow noise at higher ISOs. Knowing Olympus cameras, we know it's OK to overexpose the sensor with up to 1EV. The key is to monitor your histogram at higher ISOs and shutter speeds, no matter what ISO you need for that next winning image...

How does ISO invariance impact ETTR? Not much because consumer cameras are designed to capture more image data in the highlights. This will not change shortly.

For more on ISO Invariance, read this article.

Below is a description of how to use ETTR

To optimize your camera exposure, apply this simple method:-

1. Fix the ISO to the value you need (Go to the SCP and select the ISO)
2. Confirm the ISO is fixed in M-Mode. The next step is to set the exposure
3. Select your aperture or shutter speed (A or S mode) and check the exposure meter
4. Follow the histogram with the exposure meter on 0EV (this is 18% gray exposure)
5. The camera "auto" mode will generally select a safe or conservative exposure
6. When you see free space to the right of the histogram, increase the exposure
7. Check the histogram as the histogram moves to the right. (Do not go too far)
8. The exposure meter will show you are overexposing by a 1/3, 2/3, or 1EV
9. It's done when you are satisfied with the histogram and the exposure meter... 
10. You can now safely take your image

Your image will be overexposed. This is easy to correct in the camera or Workspace. The result is an image with less noise and more image data to work with in post-processing.

Sony A7 III with 50mm, f1.8 - ISO25600, f7.1, 1/30sec w ETTR - Raw file edited in PhotoLab 3 using PhotoLab 3 noise reduction

See this helpful video from Ron Trek. Rob has a great YouTube channel with lots of information on Olympus cameras. In this video, Rob discusses the Olympus exposure meter, the histogram, and what features we have with Olympus cameras.