We looked at the mythology associated with RAW last month, that it somehow possesses magical properties that allow it to capture image quality from any brightness range, that you can get wonderful images from any exposure. That myth has set a lot of photographers down the wrong path.
RAW is an excellent format for maximizing what you can get from a digital camera. It isn't for everyone, as we've said before, as it increases workflow and time spent at the computer. For the careful worker who wants to spend the time on the image, RAW offers some terrific capabilities to gain improved color and tonality from your camera.
To get the most out of a RAW file, you must shoot the format the best you can right from the start—RAW files require proper exposure, good light and color from a scene to perform at its maximum. That means attention to the craft of photography, which we've been doing for years independent of anything digital.
It's interesting that as digital entered the photographic world, some photographers became frightened of it and said the craft would be lost. Craft, the control of the medium through skill, practice and knowledge, long has been a core element of photography. The fear was that the computer would do everything, making decisions for the photographer and creating stunning imagery without any work by the photographer. There even was an idea that the right computer software would allow anyone to take photographs that would equal anything the pros did! This is no exaggeration. Such a statement actually was published in U.S. News & World Report about six years ago.
In reality, there's more craft for photographers when shooting digital, and especially RAW, than in shooting slide film and using highly automated pro cameras. Before I incur the wrath of slide shooters, it's important to recognize there's much craft involved in slide photography, but since little can be done to affect the image after the photo is shot, there's more that can be done in the digital darkroom.
When shooting RAW (or any digital capture, for that matter), you have to do everything you used to do with film. But unlike slides or JPEG files, the RAW file is "unfinished." You can't print directly from it and many viewers of digital files won't recognize it. You have to open it in a RAW converter, whether from the manufacturer, Adobe or an independent product like Capture One. There, you make new decisions on color and exposure until the photo can be "finished."
Exposure is the key to getting the best from a RAW file. There's a lot of discussion about 8-bit, 12-bit and 16-bit files, plus the choice between Adobe RGB and sRGB, but none of these has even a fraction of the effect that exposure has on proper tonalities, good color and noise. This is one case where the evidence is clear—the craft that comes from good exposure trumps any digital technology.
I know, you've heard that RAW lets you "fix" problem exposures. While you often can get an acceptable photograph from underexposed or overexposed images, that can cause you a variety of problems—from limitations in tonalities and weaker colors to increased noise and less efficient workflow. Just because a RAW file can be processed to deal with problem exposures is no reason to take it for granted, always "fixing" images in the digital darkroom.
With exposure above or below the optimum for the sensor, the sensor is now expected to perform its best with less than the best light on it. The middle range of tones seen by the sensor as being in the middle range of brightness allows the sensor to optimally deal with a subject's tonal range and to capture the richest colors. Underexposed or overexposed colors give the sensor less to work with.
Look at any color—if it's darker, it has more black and less chroma, or color information; if it's lighter, then it has more white and also less chroma. The same thing happens whether you expose film or digital. Dark colors have less color in them to reveal; light colors also have less color in them.
As you process a RAW file, the result is that underexposure or overexposure can mean you don't have the tones or colors you really wanted. At best, this will mean more work for you in processing your photos. You'll move one control to where the image looks good, but to correct problems, you need to make a counter-adjustment with another control. That may throw off color, so you need to make another counter-adjustment. Now, the first control looks off, so you have to go back and tweak it again. You think you have it all right, make the conversion and then find the file still doesn't look right, so you have to start over again. It can become a major workflow problem.
At the worst, problem exposures in RAW will mean you never can get the colors that were originally in the scene. Sure, you can intensify this using saturation controls, but that means more work, typically harsher tonal gradations and almost always more noise.
Noise is a problem. Digital camera manufacturers have put a lot of effort into noise reduction, and they keep getting better—as long as exposure is correct for the scene. Problems with exposure result in increased processing of an image, which will enhance and reveal noise that you don't want in the picture. Noise is strongly affected by both the type and size of sensor in the camera, the ISO setting used and the exposure. You can choose the ISO setting, you can't change the sensor, and you definitely can affect exposure.
Underexposure has a great potential for adding unwanted noise in any digital image. It's true that you can limit the noise in the image in processing, to a degree, and by using noise-reduction software. This isn't a simple fix, however, and there are trade-offs.
The first is a workflow issue. For a variety of reasons, you might not see the noise until later in the process. It can be especially noticeable in a larger print. When you go back to the image, you'll see it there, but it just doesn't always pop out at you on the computer monitor. Now you'll have to reprocess the image and print again.
The second trade-off is that removing noise can affect details in a photo. Noise is a very fine detail in an image, in a sense. If you remove it, then other fine details may be affected as well. Over-processing a photo to control noise can make it look very unnatural, with odd-looking tonal and color transitions. You're much better off minimizing noise initially by shooting at the right exposure and limiting your use of higher ISO settings (you should test your camera's ISO settings to see what it does and what's acceptable).
RAW came into the market with such hype that many photographers thought it could do miracles. One of the most common misconceptions I hear is that RAW is so adaptable that you don't have to be as concerned about exposure or color since you can fix it in the computer later. Such thinking shortchanges RAW, creates more computer work (which can be frustrating) and can give you less than the best tonalities and color.
The key: shoot it right in the first place. If you have any doubts, try another exposure. Another misconception is that RAW never requires bracketing. In a difficult lighting situation, bracketing can be helpful.
RAW has amazing capabilities. Just remember that its full possibilities are enabled only when the image is thoughtfully exposed and captured by the sensor initially. RAW makes a good exposure better; it only means a lot of work with a poor exposure.
Editor Rob Sheppard's latest book is the PCPhoto Digital Zoom Camera Handbook, a guide to advanced digital cameras. He's leading a photo tour to Peru again this summer; visit the Palm Beach Photographic Centre website at www.workshop.org.