Chapter Six: Capturing the Image—Composition and Focus
Composition
Of all the activities involved in taking a photograph, composition is by far the most subjective element and the greatest opportunity to create art. Even if your camera is mounted on a microscope so that you can record the otherwise invisible world, you still determine what to include in your photograph so it will communicate your ideas to your audience. The camera has a robust set of tools to optimize the result, but it can’t create the composition for you.
In composition, you need to be aware of conditions such as strong backlighting, the extremely broad dynamic range required for proper representation of critical components, objectionable features in the background that need to be deemphasized, inadequate lighting for certain portions of the image, motion by the subject that needs to be emphasized or eliminated, and opportunities to exploit or enhance natural lighting.
Accommodating a variety of lighting conditions can usually be addressed by choosing the appropriate metering method. While Evaluative Metering works well in many cases, it may be wise to consider either Partial Metering or Spot Metering for subjects that are strongly backlit. Just remember that—unlike Evaluative Metering—neither Partial Metering nor Spot Metering considers the point of focus in its determination of exposure; both reference the exact center of the viewfinder. This can become a challenge in some instances, such as macro photography, when you want to use a focus point other than the central focus point to achieve the absolute sharpest image of a very small portion of the composition. That’s where AE Lock justifies its existence. I use One-Shot AF, set up my composition and select the focus point I want to use. I press the Shutter button down halfway to achieve focus (the green dot appears at the right edge of the information bar in the viewfinder), move the lens to put the center of the viewfinder (actually, the spot-metering circle) on the subject, press the AE Lock button, reposition the camera to allow the selected focus point to fall on the subject, and press the Shutter button all the way down. Yes, that description seems a bit intimidating, but after you try it a half-dozen times, you’ll feel more confident about the process and it won’t seem so onerous.
How to effectively capture dynamic range in a photograph has been getting a fair amount of attention in recent years. If that’s the current challenge you face, consider using the HDR tool built into the EOS 6D. It’s not as powerful as some of the available software offerings, but it will faithfully tackle many jobs. Spend a bit of time with it so that you better understand its capabilities and limitations.
You can control interfering objects in the background by removing them or by reorienting your setup. When that’s not practical or it totally compromises the quality of the potential image, then a physical backdrop can be set in place or a visual backdrop can be created by using remote flash to grossly overexpose the background and eliminate intrusive detail. However, the more common approach to this problem is simply to use a lens with a large aperture so that you can reduce the depth of field to a point where background colors are blended and shapes seem to flow, all without creating any stark, high-contrast portions of the image.
Insufficient or incorrect lighting is often a challenge. To a very limited degree you can address this problem by manipulating one or more of the three exposure factors—ISO, aperture, and shutter speed. Truly taking control of it usually involves bringing more light to the situation. In fact, being able to supply several more light sources can greatly enhance your potential photograph. Some folks are fortunate enough to have access to banks of studio lights, but for the majority of us, it comes down to using electronic flash units. The EOS 6D has neither a built-in flash nor a flash commander for remote units, but there are a number of capable and sophisticated flash units that can help you master just about any lighting challenges you encounter.
Controlling the appearance of motion in a photograph is typically addressed by choice of shutter speed. A very short shutter speed tends to reduce or eliminate the appearance of motion, and a long shutter speed will blur the image, enhancing the appearance of motion. If you are practiced, you can select a point on the moving subject and pan by following the subject with your camera while keeping that point in the same position in the viewfinder. What the camera will record is a still subject with the world whirling by in the background. Otherwise, the secret to mastering the appearance of motion is in determining which shutter speed to use. Given a moving subject, you need to be able to estimate to some degree of accuracy the speed of the subject as viewed from a line perpendicular to the path of the subject. The subject’s speed becomes important because you want to determine just how far it will move while the shutter is open. I’ve always been fascinated with the pictures of a rifle bullet exiting a light bulb, water balloon, or grapefruit. It would seem that 1/4000 second should stop just about anything. But most rifles bigger than a .22 (and even some .22s) move the bullet at over 2,000 feet per second. So, at 1/4000 second, that bullet will travel one half of a foot, or six inches. Similarly, if you’re photographing a race car coming out of a curve at 120 miles per hour, remember it is going 633,600 feet per hour or 176 feet per second. So if you divide the car’s speed in feet per second by the allowable motion (in feet) per second, you get an idea of the shutter speed you need. As an example, if you can accept the car moving two inches during the exposure, you get 176 divided by 1/6 or 1,056. That’s a shutter speed of 1/1000 second. Can your lens handle the resulting aperture requirement, or do you need to crank up the ISO to help things out?
When you spend a fair amount of time on kneepads (a concession to advancing years, in my case) capturing close-ups of the wonders of nature, you don’t always get the lighting you want. Though you can bring electronic flash to the scene, you may want to first consider exploiting or enhancing the existing natural light. There are a number of screens and reflectors available, and in a variety of forms. For my macro photography, I like the collapsible 22-inch units that are mounted on a spring-steel hoop, which will coil into something approaching an 8-inch circle. These come with a reflective gold, silver, or white surface and generally also include a translucent surface that reduces light transmission. That’s very good when your subject is in strong sunlight. The gold is particularly good at warming up some flower colors, especially if used to reflect light up to the underside of the petals or leaves.
Focus
There are instances in which a photograph is intentionally blurred for some unique artistic expression. But for the majority of our photos, we want either tack-sharp focusing or just a wee bit of softening to eliminate some of the extraneous details. Because most, maybe all, cameras are designed to come as close to that tack sharp criterion as possible, subtle softening is usually accomplished through soft-focus lens filters or, even more common in today’s world, with sophisticated post-processing software. Photographers who specialize in weddings or portraiture seem to be driving the growth of that part of the market. If you use Adobe Photoshop, you may want to look at opening a photo (particularly a photo of an elderly person) in Bridge, then passing the photo to Adobe’s RAW processor. Move the Clarity slider to the right to show every crease and imperfection, or move the slider to the left to defocus the image, effectively removing years from the subject’s appearance.
If you can get a large enough image in the viewfinder to allow critical viewing of the portion of your subject that you want to focus on, then manual focusing is often the best and most accurate choice, but that’s available only when you have a still subject and the luxury of time. Having the camera on a good tripod and using Live View, with its 10x enlargement ability, certainly makes manual focusing easy to live with. But most photography, and especially action photography, simply does not allow for such an approach to focusing an image. The EOS 6D has a rather sophisticated automatic focusing system that is quite fast and offers enough options that the great majority of photographic situations, with a bit of input from you, can be handled quite capably by the camera.
Figure 6-1. The EOS 6D’s eleven focus points and the spot-metering circle
The EOS 6D offers 11 unique focus points. What an improvement over the days of a single focus point, and it being fixed dead center in the viewfinder! Of course, if you’re standing perpendicular to a beautiful quilt hanging on a wall, one focus point is really all you need, and dead center is probably the best place for it. But, as the composition of a photograph becomes more complex, being able to move the focus point becomes a real advantage. Then to be able to select a portion of the viewfinder and have the focusing system select the focus points by finding the closest objects in that defined zone—well, that’s just short of magic. However, it’s when you find that the autofocus system is capable of tracking moving subjects that you truly begin to see what has happened in photography since Alfred Eisenstaedt pointed his 35mm Leica at a subject, used the split-image rangefinder for focusing (often simply guessing at exposure factors), and still provided photographs that even today are considered outstanding.
Just how precisely can you position the point of focus? Well, the EOS 6D has 11 focus points available, arranged as shown in figure 6-1. The area actually used for focusing is a bit larger than the individual small rectangles would indicate, so you get pretty good coverage, but there are still some gaps. Be alert. This is a good case for not using AI Servo AF, but for using One-Shot AF. In One-Shot AF, you will be able to see the red rectangle that identifies the focus point when the camera achieves focus, allowing you to ensure that the correct portion of your composition is being used for focusing.
How It Works
A little background on the technology Canon uses in the EOS 6D: First of all, not all 11 points are equal.
Figure 6-2. Types of focus points
Each string of three blue-bordered squares shown in figure 6-2 represents one of the 11 autofocus points in the EOS 6D. (Note that the colors are purely for distinguishing critical elements, and have nothing to do with the construction or operation of the camera.) The vertical lines represent autofocus sensors that are responsive to horizontal detail, and the horizontal lines represent autofocus sensors that are responsive to vertical detail. This responsiveness is a result of the phase-detection technology used in these autofocusing systems. Phase detection essentially relies on having images with detail that runs perpendicular to the sensor lines. If the autofocus system consisted only of vertical lines, attempting to take a photograph of a dense forest of bamboo, for example, would be quite a challenge, with the lens likely hunting back and forth trying to achieve focus. When we have an autofocus point crossed by both a vertical line and a horizontal line, that autofocus point is capable of sensing both horizontal and vertical detail.
Any of the 11 autofocus points will respond to an image formed by a lens with an f/5.6 or faster aperture. There is a central horizontal red line that represents a high-precision autofocus point, and will work with lenses having an aperture of f/2.8 or faster; slower lenses will be able to utilize only standard-precision autofocus points. (Note that autofocus is performed before the shutter is tripped, so the lens diaphragm is still wide open. Focus will have been achieved by the time the lens stops down for the actual image capture.)
How Many Autofocus Points Do You Need?
Up until a few years ago, most of us were quite happy to point the dot in the center of the viewfinder toward a critical part of our subject and accept that such was the way autofocusing worked. When additional autofocus points on the viewfinder’s screen were introduced, we started moving the desired point to different parts of the composition for off-center focus. With stationary subjects, and when a greater degree of focusing accuracy is desired, this kind of manual autofocus point selection is ideal.
Figure 6-3. A photo opportunity for Automatic AF Point Selection
Consider the photo in figure 6.3 for a moment. There are two important elements in this image: the window and the walking woman. As the woman moves from under the window to the right, you compose your picture, ensuring the placement of the window in the composition. You have your camera set for One-Shot AF and automatic AF Point Selection (all 11 focus points active), so you know that as long as the woman remains the element of the picture that is closest to the camera and she is covered by one of the 11 autofocus points, you will get a well-focused photo. In waiting for the woman to have the correct posture and stride, you’ve been able to accomplish all your objectives.
In AI Servo AF mode, we enter a whole different world of opportunities for refining autofocusing. This world is designed to accommodate moving subjects. With AI Servo AF mode and Automatic AF Point Selection, you select any one of the autofocus points for initial focus on the subject, then as the subject moves, the camera selects surrounding autofocus points to continue to track the subject and maintain focus, even considering apparent motion of the subject caused by your attempts to pan the camera with the subject’s movement.
The more focus points available, the better. Consider the focusing options available with the 61 focus points available on the EOS 5D Mark III and the EOS-1D X. Wow!