High Dynamic Range (HDR) photography gives photographers the ability to present images in a way that increases the tonal range in the final image. Theoretically, the process produces images that more closely resemble what our eyes see in a scene. In practice, HDR photography and image processing can produce results that run the gamut from hyper-realistic to shockingly surrealistic.
Processing methods account for most of the differences in the final results and we'll examine those in other lessons. This tutorial will focus on the process of taking photos to be used in creating HDR images. The basic requirements for this stage of HDR imaging are the same, regardless of the desired effects in the final image.
What You'll Need
While it's possible to attempt HDR photography with any camera that allows you to adjust exposure, your results will vary widely. The list below is based on the required equipment to get the most from the time and effort you invest in taking the photos.
- a digital camera with RAW capability and manual or aperture priority exposure settings*
- a sturdy tripod, beanbag or other stable camera mount
- a cable release, remote shutter release or shutter delay setting
* Saving photos for HDR processing in JPG format will produce poor results in the final images, because tonal ranges are reduced in the compression of JPG files.
Exposure Bracketing
Taking photos to be used in HDR imaging requires bracketing exposures. This term means taking a series of photos that range from underexposed to overexposed, with a “correctly” exposed version as the central point. In HDR photography, shutter speed is the element used to control the exposure of the images. This ensures the lowest noise in your images and that the depth of field remains constant.
©Dana O. Crandell. All rights reserved.
Bracketing can be done manually or with a feature on your DSLR camera commonly known as Auto Exposure Bracketing (AEB). You'll need a minimum of three exposures, commonly at a difference of 1/3 to two full stops of exposure. Many of the highest quality HDR images start with nine or more images at 1/3 stop increments, but each situation is different. Practice will help you learn what works best for you.
Setting Up for the Shoot
While it's possible to hand-hold HDR shots, the chances of camera motion between photos is increased, as well as blurring at the slower shutter speeds. I highly recommend stabilizing your camera and using a remote release or built-in shutter delay.
- Stabilize the camera
- Set the shutter to the delayed setting or the remote release setting
- Select the lowest practical ISO setting
- Set exposure mode to aperture priority for automatic exposure control or to manual
- Set the aperture to obtain the desired depth of field.
- Frame and focus carefully and lock the focus if possible.
Manual Bracketing
If you prefer to bracket your exposures manually, you'll first want to find the right shutter speed for a correct exposure at the current aperture setting. Once that's determined, you'll then need to take an evenly divided number of over- and under-exposed photos with the same steps in exposure. Keep in mind that most DSLR camera shutter speed selectors work in 1/3-stop increments, so you'll have to move the dial three clicks for one full stop of exposure compensation.
The procedure is fairly simple. Once you've completed the setup and determined the correct exposure, adjust your shutter speed up or down by the number of stops you want to use times half the number of exposures you want, minus 1. For instance, use 1/3 stop x 3 for 7 total exposures at 1/3 stop each. Take the photo, then adjust your shutter speed by the same amount in the other direction and take the next. Continue this process until you've completed the desired number of exposures.
Automatic Bracketing
Manual bracketing can take enough time that something in the scene may change in between exposures, which can create problems in processing. If your camera offers auto-bracketing, using it can be much faster and easier. Settings differ according to manufacturer and model so the best way to learn to use this feature is to consult your user manual.
Once your setup is complete, choose the AEB settings you wish to use and actuate the shutter. The camera will do the rest.
Post Processing
©Dana O. Crandell. All rights reserved.
Shooting is only the first step in creating HDR images. Once you've gathered your sets of photos, you'll need to have access to software that allows you to blend the images into a single image and tone map the resulting image for vibrant, powerful HDR images. In the next lesson, we'll explore HDR processing using popular software packages such as Lightroom®, Photoshop® and Macphun's Aurora HDR.
