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Prefocusing for cameras with shutter lag David Mark
Photographers tend to obsess over light, and for good reason. Without proper light, you can’t take good pictures. I was on an assignment one Saturday afternoon shooting a high school soccer game, when one of the fans struck up a conversation. “Perfect day for photography isn’t it!” he said. I gritted my teeth. It was noon; there was a bright sun right overhead. It’s one of the most difficult types of light there is to work with when you’re shooting digitally. It’s no picnic with film either, yet most people think it’s a “picture-perfect” day. Years ago, film technology was limited to slow speed, fine-grain films that required a lot of light for effective photography. As a result, a whole generation of photographers learned that they need a lot of light to take pictures, which doesn’t really apply to today’s photography. With higher ISO settings, better quality films, and sensors, it’s possible to take good photos in relatively low amounts of light. Yet many people still think they need lots of light to take good pictures. In reality, it’s not usually the amount of light that’s important, but the quality and the direction of that light. In this article, I cover how to identify quality light, and how to use and manipulate light to your advantage. I also show you how to use light to your advantage and create more dramatic photographs as a result. Sunrise and sunset produce the best light of the day. During these times, the sun is low in the sky, and the light produced is rich in color and generates dramatic shadows. Golden light, as it’s known, doesn’t guarantee better pictures, but it can have a spectacular effect on your photography. Morning light is at its best from just before sunrise to about an hour afterward, while evening light is best from one hour before to just after sunset. Rather than changing your approach to photography, simply change the time of day you take photos!
As the sun travels higher in the sky, contrast increases, shadows get smaller and the light loses color until it becomes white. This is generally the poorest light of the day (unless, of course, you count the darkest part of the night.)
Contrast refers to difference between the brightest white and the darkest black within the scene you want photograph. This difference is usually measured in f-s tops. Different recording media have different contrast limits. Depending upon the particular type, color negative film can generally handle a contrast level of seven f-stops or more. Digital camera sensors on the other hand, can only manage five f-stops difference from darkest black to brightest white while holding detail at both extremes. Any more contrast, and the photographer is forced to give up either highlight or shadow detail. Recognizing high-contrast lighting can be difficult because the human eye adjusts to light so quickly, whereas cameras oftentimes don’t. You can deal with high-contrast lighting either by judging light more carefully before taking a photo, or by checking your LCD screen afterward. Some digital cameras even flash highlight areas that are overexposed. If your camera doesn’t offer such a feature, you need to examine the LCD image very closely to try and determine if the highlights have any detail to them. However, if your camera doesn’t identify overexposure, managing difficult lighting conditions can be a real challenge for digital photographers. Fortunately, there are several things you can do to deal with high-contrast lighting.
Recompose your image: Try to find a different composition that eliminates really bright or really dark areas from your scene.
Balance light: One of the most common solutions professional photographers use to deal with high-contrast lighting is to increase the light hitting shadow areas to balance them with the scene’s brighter areas. In simple terms, turn on your flash unit, or rig some accessory lights to bring out detail in areas that are too dark to show up on a properly exposed image
Filter light: Graduated neutral density filters are popular with digital photographers because of their ability to hold back bright sky areas while not affecting shadow areas. Graduated neutral density filters are half dark and half clear. Position the filter so the dark section is superimposed over the bright area and let your built in light meter (see sidebar below) set the exposure.
Block light: Sometimes you can block an overpowering light source to reduce overall contrast in a scene. Blocking light works for portraiture where placing a diffuser between the sun and your subject will both lower the overall contrast ratio and soften the light hitting your model.
All digital cameras come with built-in light meters, or sensors that measure light in any one of several different ways, depending on how advanced your camera is. Here’s a listing of the most common metering systems.
Center-weighted averaging assumes that the most important subject matter is in the center of the viewfinder, and it measures the image’s overall brightness and weights its reading to slightly favor the viewfinder’s central portion. Center-weighted averaging is a good general-purpose choice. Center metering bases its light reading on the center part of the image only. If you follow the rule of thirds religiously, center metering can emphasize to the wrong part of the composition as a result. Evaluative, multisegment, or matrix metering are more sophisticated metering systems that break the image down into zones and measure and evaluate each segment before calculating a best exposure based on typical photographic compositions. These are very good general-purpose metering methods. If your camera offers one of these three modes and you don’t want to be bothered with figuring out how to meter manually, this is your best choice. Spot metering reduces the metered area to a very small spot (the center circle) of your viewfinder. It’s useful for difficult metering conditions because you can point the spot sensor directly at the most important element in your scene and take a light meter reading off just that spot. Sophisticated cameras such as the Canon EOS 1D enable you to take a series of spot meter readings and then average them together for an overall value. It’s important when taking light meter readings to make sure you’re properly measuring the light falling on your subject. If your subject is strongly backlit, then odds are that the strong light behind your subject will fool the light meter and return a reading that’s too high for your subject. It’s better to either zoom in close to meter directly off your subject or to dial in a couple of f-stops worth of exposure compensation (to +1 or +2) to correct for the backlighting. Another important consideration when taking pictures is the direction of your light, which affects the resulting images. Here are the most common directions light comes from:
Front lighting: Front lighting is the direction most photographers work with. Your light source is behind your back and shines directly on your subject. Front lighting is nice and safe. It provides decent illumination and solves most exposure problems.
Side lighting: Position your camera and your subject at a right angle to your light source, and you have side lighting. Side light is great for bringing out texture and detail. It can also create a moody sort of image where your subject appears to be emerging from the shadows.
Back lighting: Beginners are all taught to avoid this one. Put your light source behind your subject and you have a difficult (but sometimes rewarding) kind of lighting known as backlighting. If you’re working with a backlit subject, it’s particularly important either to meter off your subject (rather than letting the strong light behind it determine the exposure) or set your exposure compensation control to add an f-stop or two of extra exposure. Although too strong a light source behind your subject can overwhelm the image, carefully controlled backlighting creates a lovely effect known as rim lighting, which produces a beautiful glow around your subject.
Another way to improve the quality of your photographs is to use supplemental lighting. Most of the time this means using either your camera’s built-in flash unit or an accessory flash unit, but sometimes it’s as easy as repositioning a couple of lamps to throw more light on your subject. The idea is simple: Throw more light on a poorly lit subject to create a better photo. Most of the time extra light is beneficial, but you do want to avoid lighting your subject from below, a style known as ghoul lighting. This casts strange shadows and produces an otherworldly appearance that can adversely affect your photographs. In fact, cinematographers have been using ghoul lighting for years; it’s the lighting used in those old black and white horror movies your parents and grandparents might have watched. When applied judiciously, supplemental lighting is one of those things that can make a huge difference in your photography. A flash, for example, is just as useful under bright light as it is in low light. In fact, its careful use in high contrast conditions can go a long way toward solving some of the most common photographic problems. Getting good results from flashes doesn’t have to be difficult. You need to understand that the camera is competing with one of the finest optical instruments ever devised—the human eye. Your eyes quickly compensate for fairly severe changes in illumination, so you tend to view a scene without realizing your film or digital sensor doesn’t see it the same way. Part of what makes using supplemental lighting challenging is recognizing when to use it in the first place.
Built-in flash is self-explanatory. It’s literally the flash built in to your camera, and it’s very useful for cleaning up shadows caused by baseball caps and other hats. If you’re shooting a group of people and somebody’s wearing a hat, turn on your camera’s built-in flash. This is one of the most effective ways to use your camera’s built-in flash. Flash is also helpful if there isn’t enough light to create a photo without blur from camera shake, but the quality of such photos is mediocre at best. Still, flash can be the difference between being able to take a photo and not being able to take one at all. Unfortunately, your camera’s built-in flash can cause just as many problems as it solves. For one thing, the flash is located just above the lens. The flash’s location is what causes red eye (when your subject’s eyes appear to glow red in a photo) as the flash’s light reflects off your subject’s eyes back into the camera lens. Another problem with built-in flash units is that they’re woefully underpowered. These flash units are generally good for a distance of about eight feet, usually just far enough to handle a group of people you’re shooting for a souvenir photo. This limitation, however, doesn’t stop people from trying to use these flash units to light major sports arenas or the Grand Canyon. Supplemental, or accessory, flash is simply an external flash you use separately or in conjunction with your camera’s built-in flash unit. There are several ways to use supplemental flash:
Hot shoe mount accessory flash: If your camera has a hot shoe (a mount that triggers your flash when you press the shutter button), then a hot shoe mount accessory flash is a great addition to your photographic arsenal. These units are frequently designed to work specifically with your camera model, and usually described as dedicated flash units. The best of these models swivel and tilt in a variety of ways to permit bounce flash and can receive information from the camera lens to tell it the exact distance your subject is from the camera.
Slaved flash units: A slaved flash relies on a built-in photoelectric cell that triggers the flash unit when another flash goes off. Although slaved flash units or slave triggers (devices that attach to non-slave flashes to make them slaves) have been around for a long time, digital cameras require a special type of slave technology because digital camera built-in flash units operate differently than built-in flash units on regular film cameras. These flashes fire a special pre-flash to calibrate some camera settings and trigger traditional slaves before the lens opens. Check out the Digi-Slave flash line for slaved flashes made specifically to use with digital cameras. Keep in mind, if you have a DSLR, regular slave units will work just fine.
Reflectors: Sometimes the answer isn’t necessarily an extra light source but simply a matter of redirecting an existing one. Reflectors serve this purpose. You can either use one of the many photographic reflector systems (many of which are collapsible and have different coverings to change the color of the reflected light), or you can make your own reflector with a sheet of white foam core board, or even aluminum foil glued or stapled to a lightweight sheet of plywood. Then you position the reflector so it bounces your light source into the shadow areas.
Diffusers: Photographers place diffusers between their subject and the light source to soften the light and reduce its intensity. Commercial versions are available, or you can fix a sheet across a sunlit window or stretch a pillowcase over a window screen or homemade wooden frame to create your own diffuser