Is the transition from the highlights to the shadows subtle or sudden?
Contrast describes how the highlights transition into the shadows. The brightest areas of the image are the highlights. The darkest areas are the shadows. In between, the image will have lights, midtones, and darks.
Check out the Poring Over the Picture spread on pages 2–3 (the one of Tony at the lake). You will see that I noted that I exposed the image such that the details of the hair highlights would not blow out to white. This meant that the details in the shadow are too dark (at least too dark for a perfectionist). So, you could say that this image has too much contrast.
The dynamic range of a scene describes how much brighter the brightest spot is than the darkest spot. The human eye can see a wider dynamic range than our cameras can record. Likewise, our cameras can record a wider dynamic range than our monitors can display and, typically, our monitors can display a wider range of light than printers can print. Every generation of gear narrows the gap between what we see and what it can capture, display, or print. Eventually, I expect that this gap will become a non-issue. In the meantime, as this is a book on lighting, throughout the many pages ahead, we will discuss how to manage these differences by adding light to and, in some cases, subtracting light from our shots.
Here is a quick example of how lighting can adjust the dynamic range of a scene so that the camera can record it more faithfully (Figures 1.15 and 1.16). A car outdoors on a sunny day has a huge dynamic range. The glints of light coming off the chrome are the brightest highlights—in fact, they are so bright that we call them spectral highlights, meaning that they are direct reflections of the light source (in this case, the sun). At the other end of the dynamic range are the shadows—in this case, the treads of the tires just where they meet the asphalt.
Figure 1.15. Even though I could distinctly see the difference between the tire and the asphalt, there was too much dynamic range in this scene. Exposing to see the tire details would have blown out important highlights.
Figure 1.16. Adding light into the shadows actually reduces the dynamic range of the scene. In this shot, I used a pair of Speedlites to add light underneath the fenders.
In direct sunlight, there is often too much contrast. Here the details in the shadows of the tire treads merge to black. We might be able to see most of the details between the two extremes. Yet, as shown in Figure 1.15, the camera cannot record this full range of light and shadow. So, as the photographer, I decided to expose for the detail in the hood and let the shadows fall where they may. As you can see, the tread of the tires cannot be distinguished from the wheel well or from the asphalt.
As we will explore in greater detail later in the book, one option is to add light into the shadow areas so that the dynamic range of the scene is reduced to the range that the camera can record. In Figure 1.16, you can see can see many more shadow details because I used two Speedlites to create fill flash (Figure 1.17).
Figure 1.17. By adding fill flash, the contrast is reduced into the dynamic range that the camera can record. So, shadow details are revealed.
Exposure and Post-Processing
When the difference between the highlights and the shadows is beyond the dynamic range of the camera, then either some of the highlight details will be captured as pure white, some of the shadow details will be captured as black, or both will happen. We call this blowing out the highlights and crushing the shadows.
In the field, you will often have to decide what is most important and skew your exposure to protect that portion of the image. For a wedding portrait, the details of the bride’s dress are likely more important than the details of the groom’s tuxedo. So underexposing a bit to preserve the highlight detail in the dress would be a safe decision.
In Chapter 2, we will talk about the benefits of shooting RAW files instead of JPEG files as one way to maximize your options for challenging shots with a wide dynamic range. Then, by using a full-featured image-processing program—like my favorite, Adobe Lightroom—you can often save important highlight details with the Highlight slider and reveal details in the shadows with the Shadows slider (Figure 1.18).
Figure 1.18. In the Develop module of Adobe Light-room, the sliders for White Balance, Tone, and Presence can go a long way to restoring the look of a poorly exposed capture. Still, using software to fix problems is no substitute for learning to light.