In a low-key image, dark tones dominate the photograph. Small, bright highlights punctuate the shadow areas, creating the characteristic mood of a low-key image. The position of the light source for a typical low-key image is behind the subject or behind and off to one side, creating deep shadows.
In pre-digital days, the appropriate exposure usually centered around how far the photographer could reduce the exposure before the highlights appeared dull. Today, this approach should be avoided at all costs, especially when black velvet-like tones are your benchmark for quality.
The Camera RAW dialog box reveals this low-key image was exposed as if it were a mid-key image and exposed for the dark side in Photoshop.
Exposure for Low-Key Images
For digital photographers interested in low-key images, an SLR loaded with a fine-grain black-and-white film is a hard act to follow. The liquid smooth transitions and black velvet-like quality of dark low-key prints of yesteryear is something that digital capture is hard pressed to match.
With digital capture, the reality is that underexposure in low light produces noise and banding—steps rather than smooth transitions of tone—in abundance. The solution is surprisingly simple, however, if you shoot in the RAW format. Be generous with your exposure to the point of clipping or overexposing your highlights, and only attempt to lower the exposure of the shadows in Adobe Camera RAW.
Although the final outcome may require deep-shadow tones, first get the shadow tones away from the left-hand wall of the histogram by increasing, not
Adobe Camera RAW rescues the highlights —sometimes automatically.
decreasing, the exposure. It is vitally important, however, not to increase the exposure so far that you lose or clip highlight detail. The original exposure of the image used in this project reveals that the shadow tones, visible as the highest peaks in the histogram, have been generously exposed in-camera, so that noise and banding have been avoided. The tones have moved well to the right in the histogram.
The highlights, however, look as though they have become clipped or overexposed. The feedback from the histogram on the camera’s LCD would have confirmed clipping at the time of exposure—the tall peak on the extreme right-hand side of the histogram—and if you had your camera set to warn you of overexposure, the highlights would have flashed to advise you of your faulty exposure settings. Adobe Camera RAW can recover at least one stop of extra highlight information when the Exposure slider is dragged to the left.
With some attention to the histogram during the capture stage, you can master the art of pushing your highlights to the edge. So, if your model is not in a hurry (mine is watching a half-hour TV show), take an initial exposure on Auto, then check your camera for overexposure. Increase the exposure using the exposure compensation dial on the camera until you see the flashing highlights. When the flashing highlights start to appear, you can still add about one extra stop to the exposure before the highlights can no longer be recovered in Adobe Camera RAW.
If the highlights are flashing and the shadows are still banked up against the left-hand wall of the histogram, increase the amount of fill light, i.e., reduce the difference in brightness between the main light source and the fill light. If flash is the source of your fill light, drop the power of the flash by at least two stops and choose the ‘Slow-Sync’ setting—a camera flash setting that balances the ambient light exposure and flash exposure—so the flash light doesn’t overpower the main light source positioned behind your subject.
Before massaging the tones to create a low-key image, check that the tones are smooth and free from color and luminance noise. Zoom in to 100 percent magnification for an accurate preview and look for any problems in the smooth, dark-toned areas. Set the Luminance Smoothing and Color Noise Reduction sliders to 25 to remove the noise. I also recommend that the Sharpness slider be set to 0 at this point. Selective sharpening in the main editing space helps keep the tones as smooth as possible, rather than committing to global sharpening in the Adobe Camera RAW dialog box.
Create the low-key look by dropping the Exposure and/or the Brightness sliders in the Adjust tab. You can continue to drop these sliders until the highlights start to move away from the right-hand wall of the histogram. Select the ‘White Balance tool’ and move your cursor over the deeper shadows. This will give you an idea of the RGB values you are likely to get when this image is opened into the editing space. Once you approach an average of 15 to 20 in all three channels, you should have the low-key look you’re after.
To enhance this image further, I added a vignette using the Adobe Camera RAW dialog box in Photoshop CS2. To drop the RGB to B&W, I used a technique that extracts the luminance values from the RGB file and usually gives a superior result to lowering the saturation or choosing the Remove color command.
All your work will be for naught if the printer or surface quality of the paper cannot handle these smooth, dark tones. If printed well, the print will stand up to really close scrutiny at close range.