HDR photography gets a bit of a bad rap from people who think its sole purpose is for special effects photography. That is not the case all. HDR stands for “High Dynamic Range” photography. It actually originated as an attempt to make photographs look more realistic.
Cameras do not have as large a dynamic range as the human eye. If you look at a landscape on a sunny day, your eye can see the clouds in the sky at the same time as it can see the details in the shadows. Cameras can’t yet do that. If you expose for the clouds in the sky, you lose the details in the shadows. If you expose for the shadows, the sky is blown out. That is why so often shots we take of landscapes do not seem as vivid as we recall the scene being. While you can compensate to a certain extent in post-processing the result often yields grainy images.
HDR photography attempts to remedy this by combining multiple exposures. In the simple example above, you would take three separate shots, one exposing the sky correctly, one exposing the shadows correctly, and one exposing the midrange correctly, and then combine the three to approximate what the eye actually sees.
This sounds complicated, but modern cameras and software make it easy. In fact, modern cameras make it easy to take HDR photos with 3, 5 or 7 images.
The image below is a HDR composite of 5 different exposures.
The next image is the middle of the 5 exposures used for the HDR photo above.
Compared to the HDR image, the single exposure image has blown out highlights in the streetlight and at the base of the lighthouse, and has no colour or detail in the lake or sky or below the pier.
HDR is useful whenever your subject has a larger dynamic range than your camera can handle.
It can be particularly useful for shooting into the sun or for getting texture in snow as in the image below.
HDR is also useful for indoor architectural photography. If HDR had not been used for the image below of the Notre-Dame Basilica in Montreal, the bright chancel would have been blown out and there would have been little or no detail in the dark areas under the balconies.
Making the HDR Image
- Camera Settings – taking the photo
Use a tripod.
Set your camera to Aperture Priority mode (Av on Canon, A on Nikon), with a fixed (not Auto) ISO setting, so that only the shutter speed changes between exposures.
Most cameras have an “Auto Exposure Bracketing” setting that will allow you to set the camera to take 3, 5 or 7 shots at different exposures automatically. You may have to consult your camera manual.
The photo below shows a Canon 6D set to take 5 shots, the first 2 stops underexposed, then 1 stop underexposed, then correctly exposed, then 1 stop overexposed, then 2 stops overexposed.
If the camera is set to the timer mode, you only have to press the shutter once and it will automatically take all 5 shots one after the other.
Most cameras will not let you take an exposure longer than 30 seconds unless you use the manual “bulb” setting. When shooting HDR in low light situations, to ensure that your longest exposure is 30 seconds, set up your camera as above and press the shutter half way down to see what shutter speed the camera will automatically expose for. Then, assuming you are going take HDR shots over a range of -2 to +2 EV (as above) change your ISO so that the shutter speed is shown as 8 seconds. This will result in exposures of 30, 16, 8, 4 and 2 seconds. (If you are going to shoot a range of -3 to +3, set your ISO so that the metered shutter speed is 4 seconds).
- Combining and Processing the Images
Combining and processing the images is done most easily using a plug-in. The two most popular ones are Photomatix (http://www.hdr101.com/photomatixv5/) and Nik HDR Efex Pro (http://www.google.com/nikcollection/products/hdr-efex-pro/). Both will work as plug-ins for Lightroom and Aperture. HDR Efex Pro will also work as a plug-in for Photoshop and Photoshop Elements. Although HDR Efex Pro is a little more expensive than Photomatix, it comes as part of a suite of 7 plug-ins, so you get an additional 6 plug-ins for the price.
There are good video tutorials for using both of these tools on the web sites linked above.
Basically, it is just a matter of selecting the 3, 5 or 7 images you took in the Aperture or Lightroom browser, and pulling down a menu to invoke the plug-in. The software will then combine the images and give you a choice of various effects you can apply.
With a little practice and experimenting, you will find that you can process HDR images quickly and effectively.
- Useful Links
Photomatix – HDR Plug-in
Nik HDR Efex Pro – HDR Plug-in