Exposure Bracketing – What is it and when should you use it?

Exposure bracketing is a photographic technique where multiple shots of the same scene are taken at different exposure settings to capture the full tonal range and merge them during post-processing.

This article provides a breakdown of the concept and discusses its pros and cons, and covers:

·         What is exposure bracketing?

·         How do you bracket exposures?

·         What are the advantages and disadvantages of exposure bracketing?

·         When should you use exposure bracketing?

What is Exposure Bracketing?

Sometimes, when there is much contrast, your camera may be unable to capture the full tonal range of a scene.  As a result, the camera may not capture sufficient detail in the shadows and/or highlights, affecting the quality of the image.

You use exposure bracketing to prevent that issue.  Exposure bracketing involves taking multiple shots of the same scene with different exposure settings to capture the full tonal range and blend them using software like Adobe Lightroom or Photoshop.

How do you bracket exposures?

Exposure bracketing involves effort when taking photos and when developing them afterwards, as follows:

1. Taking multiple shots:  You set the camera to automatically take several consecutive shots of the same scene, each shot at a different exposure level.  These exposures typically vary by adjusting the shutter speed, but you could also do this by adjusting the aperture or ISO settings.

   Using a tripod to take these shots is easiest, because you’ll avoid moving the camera which reduces the need to align the shots during post-processing.  It also reduces the risk of blurry shots if the camera selects a slow shutter speed.

   However, it is feasible to manually shoot multiple shots with some practice.

2. Varying exposure levels:  The camera will typically take one shot at the standard exposure determined by the camera's light meter.  Then it will take additional shots, typically one or two stops overexposed, and one or two stops underexposed relative to the standard exposure.

   Due to the higher tonal range that recent camera models can capture, separating exposures by two or three stops (rather than one stop increments) is usually feasible.

3. Merging or selecting the best shot:  After capturing the bracketed shots, you can choose to merge them together using software such as Adobe Lightroom or Photoshop to create a high dynamic range (HDR) image.  This process is called ‘exposure stacking’. Alternatively, you can select the best-exposed shot based on your preference or the requirements of the scene.

   Merging the shots in Lightroom is straightforward, and the results are usually good.  However, results may not be optimal with moving objects (trees, water, grass, vehicles, animals, etc.) as ghosting may become obvious, making these objects partially transparent or blurred in the final image.

   Manually blending shots in Photoshop is a more advanced method that gives you more control over the blending process.  Typically, you would blend in the bright area (e.g. the sky) into the shot that was exposed for the shadow areas (e.g. the foreground) using a mask or a brush.  This means you can be more selective and avoid issues like ghosting.  In this case, you need to prepare the images prior to merging them so that they are similar in exposure level to avoid harsh transitions. This last step of the process is covered in a separate article that you can find here.

Advantages of Exposure Bracketing

• Full Tonal Range:  By exposure bracketing, you can make sure you capture the full tonal range of the scene.  This allows for more flexibility during post-processing.

• Less Camera Work:  Just shoot, and you can be pretty sure that you will have captured the full tonal range, without having to check your histogram.  Sometimes, you’ll find that one of these exposures is sufficient, thus avoiding the need to blend exposures later.

Disadvantages of Exposure Bracketing

• More Photos:  You end up with multiple shots of the same scene (usually 3 for each time you press the shutter release button), which slows down the post-processing effort in several ways.  Firstly, importing your photos will take longer.  Secondly, it requires extra effort to select the preferred shot(s) for further processing.  And thirdly, your memory cards and disk drives will be full quicker.

• Post-Processing:  Post-processing is required to blend the images.  This could range from a simple HDR blend in Lightroom to more complex blending in Photoshop.  This can be time-consuming and may require advanced editing skills.

• Shutter Delay:  Usually, the timer on your camera must be turned on for exposure bracketing to function.  This introduces a delay (say 2 seconds) before the camera takes the shot, which may make it difficult to capture moving scenes at the right time (such as breaking waves).

• Lazy Photography:  Because exposure bracketing involves less camera work, and you usually end up with a good exposure to create an image, it becomes easier to just leave the exposure bracketing feature on your camera turned on all the time.  As a result, you’ll spend less time checking the result in the field, you’ll learn less about photography, you’ll end up with many ‘just in case exposures’, and you may find that you didn’t get the shot you were hoping for (and you may not get a second chance to shoot the scene).

• Handheld Images:  Typically, your shutter speed will vary when bracketing, which means that your longest exposure(s) could get blurry if you’re shooting handheld.  Also, you will likely move your camera in between shots if you’re shooting handheld, which complicates blending later.  Thus, it becomes a reason to shoot on a tripod (even if the shutter speed is fast enough).  Exposure bracketing while shooting handheld requires practice (but can be done, especially with today’s camera and lens stabilisation).

When should you use exposure bracketing?

Exposure bracketing is particularly useful in situations where the contrast between the brightest and darkest parts of the scene is too high for the camera's sensor to capture in a single shot.  Common scenarios include landscape photography with bright skies and dark foregrounds.  You’ll likely encounter this scenario when you shoot into the light at sunrise or sunset.

By capturing multiple exposures and blending them together or selecting the best shot, exposure bracketing helps you achieve optimal exposure and preserve details in both the highlights and shadows of the scene.

However, you should be mindful of the extra cost (more memory cards and disk space) and effort that it introduces to process your photos.  So, I would recommend not to have exposure bracketing turned on all the time, and only turn it on when required.  So, when is it required?

Let’s have a look at the histogram of a few photos:

A histogram of a balanced image without any clipping of the darks or lights.  There’s no need for exposure bracketing.

A histogram of an underexposed image with clipping of the darks.  There’s no need for exposure bracketing if you increase the exposure. You can achieve this by using the Exposure Compensation (+/-EV) Dial to increase its value until the histogram is balanced.

A histogram of an overexposed image with clipping of the lights.  There’s no need for exposure bracketing if you decrease the exposure. You can achieve this by using the Exposure Compensation (+/-EV) Dial to decrease its value until the histogram is balanced).

A ‘U-shaped’ histogram with clipping of the darks and lights.  It looks like the image is under and over-exposed at the same time.  This is an example of a scenario where exposure bracketing may help.  One shot to expose for the darks, one shot for the midtones, and one shot to expose for the lights.

‘U-shaped’ histograms are typical of high contrast scenes that you may encounter when shooting into the sun, such as a sunrise or sunset.  Or with stormy, cloudy conditions where the sun is poking through heavy clouds but not shining directly on the foreground.

In many cases, shots with a ‘U-shaped’ histogram can be corrected during post-processing by increasing the blacks and shadows and reducing the whites and highlights, especially when the shot was taken with a recent, high-end camera.  In some cases, though, you’ll notice there is some loss of detail in the highlights when compared against an underexposed shot.  So, in cases where both the darks and lights are clipped, or are close to being clipped, I’d suggest using exposure bracketing when taking the photo, especially since the histogram on your camera is not as accurate (or should I say easy to read) as the histogram in Lightroom.

So, I recommend to always check your histogram before you decide to turn on exposure bracketing on your camera.  You’ll find that, often, exposure bracketing is not required, especially when you have a recent camera.  Having said that, it’s better to be safe than sorry. 

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