Dynamic Range can be Tough to Explain
In the simplest form, dynamic range refers to the degree of light in a scene, from the darkest shadows to the brightest highlights. But to a beginning photographer, this can be unclear, especially when the term HDR, or High Dynamic Range, is often misused.
The first facet that confuses people is the vast difference between what the human eye can see and what the camera can see and differentiate. Look out your window at the house or building across the street. You can see all of the details in the building, including the shadows under awnings and the brightest part of any white paint. You can also see all of the details, or lack thereof, in the sky behind it, no matter how bright it is.
But if you took a picture of it with your camera, the shadows would be too dark to see, or the highlights, especially the sky, would be too bright to contain any detail. Most likely, both things would happen. You look at the display on your camera’s LCD and then look at the scene and wonder what happened. Dynamic range happened.
Here’s another example we have all seen and experienced. You are at the beach. You stand a family member on the beach with the sea and sky to their back. It’s a beautiful scene you want to capture for your memories. You take the picture. Most likely, the ocean and sky still look great, but you can hardly make out the person because they are too dark. Or, if you were close enough to the person, they may look okay, but the scene behind them is completely blown out. It’s dynamic range again.
The human eye is capable of seeing a wide dynamic range. It can adjust itself to see everything from the brightest light to the darkest shadows. But the camera doesn’t have the processing power of the human eye and brain. They are getting better every year, but you still have to account for it.
The other source of confusion is HDR. This acronym simply means High Dynamic Range, such as the two examples above. But in recent years, computer software has been developed to process high dynamic range images to make them pleasing to the eye for some people. In addition, those processes can be pushed to give a very surreal look to a scene. Because of the name of the process, these images have been incorrectly labeled HDR. The look has been called HDR, even though people use the process on images with very little dynamic range.
As a Photographer, What can You do About it?
There are at least three different methods depending on the scene, your desired results, and your skills as a photographer and processing software. The first way is the same way it’s always been done. When Ansel Adams got back with one of his famous landscapes, he went into the darkroom and developed his images. Because of the high dynamic range of many of his landscapes, he used a process known as dodging and burning. This was a complicated process that required a high level of skill and accuracy.
1. Turn to Post-Processing
Fortunately, all it needs with modern software is whatever tool you are comfortable with and a couple of sliders. Post-processing is outside the scope of this article, but if you take any image you have shot where the dynamic range is too high and simply use the shadow and highlight sliders, you will be able to recover most, if not all, of the details. This is the easiest method and should always be your first line of defense.
2. Using a Tripod and Two Identical Photos
The second method requires a bit more skill but can fix almost any HDR image. First, when shooting, you will need to be on a tripod as it requires at least two identical photos. And when I mean identical, I mean the scene, not the exposure. Everything in each image has to be in exactly the same place.
So, you take one shot exposing for the shadows and another exposing for the highlights. If the scene has a very high dynamic range, you may need more variations, but most of the time, two or three are enough. Then, back in the digital darkroom, you use your processing software to merge the two (or more) images taking the best exposure from both to create a single, well-exposed picture.
3. Use Manual Mode to Control the Flash
The final way is done entirely in the camera at the time of taking the picture. A professional photographer taking a portrait at the beach will have various lights and light modifiers to control and mold the light to their exact needs. But you don’t have all that, so let’s get that excellent vacation picture with just your camera and a flash. You will need to know how to shoot in manual mode and control the output of your flash.
First, take an exposure reading of the sea and sky and set your camera in manual to that exposure. I would suggest taking a reading in aperture priority to get the depth of field you are looking for, then use that aperture in manual mode along with whatever shutter speed the camera selected.
Next, turn on your flash and dial it down to a low setting. Take your picture and check the exposure on your subject. This will take a little trial and error. You will want the flash to give just enough light for a natural-looking exposure. The tendency is to use too much, giving the subject that caught in the headlights look. A person looking at the photo should not be able to tell that a flash was used.
Dynamic Range in a Nutshell
Dynamic range is something you will have to experiment with and learn to adjust for. You will get a feel for a scene and know the best settings intuitively to capture it with enough experience. You will also learn when the dynamic range is just too high and can then decide if the shot is worth the extra effort to capture correctly.