Metering vs. Lighting: Handling High Contrast
By Dave MontizambertWhat is the difference between good exposure and good lighting, and how do you use a reflected mode to meter high-contrast scenes? Dave Montizambert breaks it down.
Photographer and author Dave Montizambert lectures internationally on lighting and digital photography. His studio, Montizambert Photography Inc., has been creating imagery for international and national clients for over 25 years. To learn more about his photography and books, visit his Web site. You can also find his video courses on Software Cinema.
The first step to lighting is understanding the art of metering. Let’s start off with a look at basic metering for those of you who never did learn or have just forgotten. Once you take your camera off automatic and set it to manual, and then pick up the metering tool of choice—a handheld meter—the first question you need to ask yourself is, “What should I meter for?” Imagine a portrait of two people such as the yoga instructors below, Tony and Gillian—Tony with dark flesh and Gillian with very light flesh.
Which of these two should we favor with our meter? The one who is paying you is a good answer, but technically speaking that’s not correct. If we favor the dark skin by taking a reflected meter reading directly off a fully lit area of it, we will end up with an exposure that looks like the image below.
If we favor the lighter skin by taking a reflected meter reading directly off a fully lit area of it, we will end up with an exposure that looks like this image:
Is either of these exposures correct?
Some of us have been taught to underexpose light subjects and overexpose dark ones to show more shape. But what if they are both in the same shot? The answer is that you expose for neither. You don’t expose for tones; you light for tones. Shape light objects primarily with shadow, and shape dark objects primarily with specular highlights. But if you don’t expose for tones, then what do you expose for?
If I were to use a handheld meter to take a reflected meter reading off a solid-white, evenly illuminated subject such as a white seamless backdrop, and positioned the meter so that it saw only the white paper, it would give me an aperture/shutter speed combination relative to camera sensitivity setting (ISO) for what it thinks is a good exposure. If we adjust our cameras to this setting—let’s say it’s f/11 at 1/60th second and ISO 100—and take a picture, what do you suppose this white seamless paper will look like in the image? Now suppose we swap the white seamless paper with a black seamless paper, leave the lighting as is, take another reading (f/2 at 1/60th second and ISO 100), and then capture a second image with this new setting. What do you suppose the black seamless paper will look like in the image? And now suppose we swap the black seamless paper with a mid-gray seamless paper, leave the lighting as is, take another reading (f5.6 at 1/60th second and ISO 100), and then capture a third image with this new setting. What do you suppose the mid-gray seamless paper will look like in this image? The answer to the last three questions: They all appear the same! They all appear to be middle gray. Is this correct? Should a white seamless backdrop be middle gray? No! Should a black seamless backdrop be middle gray? No! Should a mid-gray seamless backdrop be middle gray? Why, yes. Then why does the reflected meter tell us to use camera settings that will make the white backdrop and the black backdrop incorrectly exposed but give us the correct settings for the mid-gray backdrop?
The reason for this is that a meter knows only one thing: middle gray. It tries to make everything it sees appear middle gray. In fact, if it is seeing more than one tone, it will average all those tones to make what it thinks will be a middle gray tone. Since the meter tries to make everything it sees appear middle gray, then a reading off a middle gray object like the mid-gray backdrop will give you camera settings to make it appear middle gray. Since its true tonality is middle gray, it will be properly exposed. Now, what if we tore a piece from the mid-gray seamless backdrop and placed it over the white seamless, then took a reflected reading off the mid-gray paper scrap, being careful to read only the gray paper and not the white, set our cameras to the recommended f/5.6 at 1/60th second and ISO 100, removed the gray paper, and then took another picture? What do you think the white seamless would look like? What if we did the same procedure, but instead of photographing the white seamless backdrop we photographed the black seamless backdrop at f/5.6, 1/60th second, and ISO 100? What do you think the black seamless would look like? Well, the white paper would look white and the black paper would look black. In other words, they would be correctly exposed.
By metering off the mid-gray paper fragment—or better still a middle gray card—the meter gives us camera settings that will make middle gray appear as middle gray in our image. If we make middle gray look middle gray, then white will photograph as white and black will photograph as black. In fact, all other fully lit tones, if present, will fall into place accordingly. If there is not a mid-gray tonality to take a meter reading from, we can temporarily add one to meter off, then remove it before shooting. Or if you are very good at recognizing tones—knowing where they should fall on the gray scale—you can take a reflected meter reading off your subject directly and then alter your camera exposure setting by the correct amount from what the meter reads, to place that tone correctly in your image relative to middle gray. For example, the white seamless paper should be white with detail, which is two stops brighter than middle gray. If we had taken the f/11 reflected reading and opened up two stops from what it read, we would have set our cameras to f/5.6, the same setting as the reading we got from the mid-gray paper. However, recognizing tones is difficult, especially when they are colors. That’s why reading off a fully lit mid-gray tone like a middle gray card, which you can put in your shot to meter off then remove prior to shooting, is an easier and more consistent way to get correct exposures. But what is a correct exposure?
A correct exposure is what you see when a fully lit area of a subject’s true tonality is placed at its correct value in the image so that its tonal brightness appears the same as it does in reality. For instance, the true value of my skin is about one stop brighter than middle gray (depending on the time of year) and for a proper exposure it should be placed at that value in the image. Keeping that in mind, look at the next two images and pick out the one with correct exposure.
If you picked the first one you are correct, and if you picked the second one you are correct. They are both correct exposures! The one on the left is a little tricky. It has very dark shadows, which in gear-head speak would be referred to as high shadow contrast. However, the lit side of Gillian is represented correctly in the image; therefore, this is a correctly exposed picture. If you thought that the image was an incorrect exposure, you were mixing exposure up with lighting. Even though you may not like the lighting position and shadow contrast in the picture, you have to agree that it is correctly exposed.
Technically speaking, you can never say that lighting is correct or incorrect. Lighting is an opinion, whereas exposure is a hard, cold fact. Lighting is subjective, exposure is objective, and when sizing up a problem image such as the one above, it is important to determine which is the issue. Sometimes the objective can be considered subjective when you decide to under- or overexpose a subject for a certain mood or effect, as with the overexposed flesh tones that are often popular in fashion and glamour. In the image at the top of this article, Michelle Snow’s flesh is grossly overexposed, by around one and a half stops. Is this a correct exposure? No. Is it a good exposure? I think so, and so did the client. So we could say that this incorrect exposure is a good exposure, since it better portrays the feel we were after. In a nutshell, correct or incorrect exposures are objective and good or bad exposures are subjective.
The subjective, creative part of photography is lighting. You can make a shadow any density darker than the true tonality you want and you can make a specular highlight any density you want brighter than the true tonality it sits upon. You can also make the edges of shadows and specular highlights as soft or as sharp as you want. The creative part of lighting is manipulating these areas to create the lighting that will interpret the subject’s form the way you want, as well as placing the whole contrast range of your set, relative to middle gray.
So to answer the question of whether you expose for Tony or Gillian: The answer is neither. You expose for middle gray, and they will fall into place relative to middle gray.Category: How-ToClick for more articles of: Dave Montizambert