High Dynamic Range (HDR) Photography
The "dynamic range" of a photograph is a measurement of the difference between the lightest of a photo and the darkest parts; it's a way to describe how much information your camera is able to record.
Sometimes the lighting contrast of a scene exceeds the dynamic range of a camera, meaning that the world in front of your lens contains both brighter and darker parts than the camera can record. If not enough captured information, you can end up with your shadow areas "crushed" to black patches, or light areas "blowing out" to fully white holes in the image.
High dynamic range imaging techniques stretch the capabilities of your camera to capture a high-contrast image with dark shadows and bright highlights, with everything being well-exposed and no information loss.
How to Create HDR Photographs
Many modern digital sensors capture so much information that even in high-contrast scenes, you can generally pull back details that look ‘lost’ to the naked eye. That will still only take you so far though, and the best way to make HDR photographs is to take multiple images at different exposures and then merge them together later in software. Most cameras have a special feature to help you automate this, called Auto Exposure Bracketing (sometimes also called Auto-Bracketing or just Exposure Bracketing).
You’ll need to have software capable of merging your images, and if you’re shooting in RAW, it will need to be able to merge RAW images (unless you’re willing to convert to JPEG first). In part two of this tutorial we’ll look at how you can merge your images using Adobe Camera Raw.
How to Use Auto Exposure Bracketing (AEB)
AEB is a useful way to quickly make more than one exposure, with the intention of merging them later. It tends to be better than making changes manually because you can fire them off in quick-succession, meaning your conditions don’t get the chance to change too much, something that would negatively affect your images.
On your DSLR, look for a BKT option. On my Nikon D800 mine is top left. On some cameras this feature might be assigned to a Fn button, or available through menus.
While holding that option you should be able to make some changes. You’ll see mine says 3F and 1.0 and the exposure scale has three vertical lines on it. Here’s what all of that means:
- 3F: the camera will take three frames (images). You can change this to suit, the minimum for an effective HDR is three and is a good number to choose for most HDR images. Five or more will give you a greater dynamic range but if you’re shooting in RAW you also need to consider the file sizes and processing power needed to merge multiple images.
- 1.0: this means that the exposure will adjust by one stop in either direction of my first shot (so -1 and +1). What you choose will depend on your environment and what you want the image to look like, but you can increase in increments.
- The three vertical lines indicate where my exposures will be in terms of dark to light, and how many images I’m taking.
If I selected five images at one stop, two extra lines would be added and if I chose five images but reduced the ‘stops’ there would still be five lines but they’d be closer together. Closer increments generally make for more natural-looking merges. If you have huge gaps between your exposures you'll end up with something very high-contrast and that looks unnatural.
When you go to take your images, you’ll select settings as you would for an average exposure, and then press the shutter the number of times that fits with how many images you’ve chosen to take, or hold it down to fire them off instantly.
When you take your images, remember to keep your settings the same between shots (the AEB setting will adjust what’s needed) and to try not to move: you need your photos to be as close to the same as possible. Some people prefer to use a tripod but personally I find handheld is generally okay; you don’t need to be exact as ACR has a ‘de-ghost’ feature.
When you’re finished taking your images remember to disable AEB again.
Using AEB in Another Camera Mode (Not Auto or Manual)
It’s worth mentioning that if you use your camera in a particular mode, how AEB works can slightly differ. For example, in aperture priority your aperture will stay the same and AEB will change the shutter speed in order to adjust the exposure. In shutter priority it’s the opposite, the aperture changes while the shutter speed stays at whatever you’ve set it at.
A Note on Faux HDR or Tone Mapping
Sometimes HDR is ‘faked’ by taking a regular photograph and making two extra versions of it, one under-exposed and one over-exposed and then those are merged to create an ‘HDR image.’ Obviously, this doesn’t truly give you a high dynamic range as you’re using the same photograph which has the same amount of data recorded. Tone mapping can be useful for bringing out areas of good light or shadow that you want to preserve but gets lost in the editing of your single image.
How to Record Images for HDR Photos
HDR doesn’t work well for every subject. People are probably a good thing to avoid, firstly they move and secondly HDR images of people always look slightly odd and unnerving. Other things that move are tricky too, like running water. That’s not to say you can’t make an HRD image from them, but you’ll need to take any movement into consideration.
If you have a particularly bright sky, it might be worth ‘stopping down’ (reducing exposure) to darker than you might usually, just to make sure that you get the best possible options from your bright areas later.
If light is lacking in your whole scene, you might then find it beneficial to use a tripod so that you can do a slightly longer exposure each time. Keep an eye on your ISO to make sure your camera isn’t compensating for a lack of light by increasing it too much, as you’ll introduce noise into your images.
The most popular subjects to make HDR photographs with are landscapes and architecture. It can be tempting to take multiple images of everything to always give you a high dynamic range, but as mentioned, your hard drive won’t thank you for that. Instead, try to make calculated decisions as to when to use HDR: when there’s a high contrast scene or a building where you want to bring out more details for example.
More HDR Photography Tutorials
- Busted! 7 Myths About High Dynamic Range PhotographyBen Lucas29 Mar 2015
- 10 Amazing Photoshop HDR Photo Effects (Pro PSD Actions)Andrew Childress12 Oct 2018
- How to Make a Long Exposure High Dynamic Range (HDR) PhotoHarry Guinness11 Nov 2015
- How to Merge and Edit High Dynamic Range Photos in Adobe Camera RawMarie Gardiner30 Apr 2021