As described in the previous chapter, simply letting the right amount of light into the camera to make a correct exposure is just the beginning of our task as photographers. The real challenge is learning how to control the side effects of each of the settings and balance them effectively. That is what it takes to be a savvy photographer. In this chapter, we’ll look at aperture settings in greater detail; in chapter 3, we’ll fully explore the implications of shutter speed selection.
“The real challenge is learning how to control the side effects of each of the settings and balance them effectively.”
The Mathematics of Aperture (Nerdy but Helpful)
The “F” number that denotes an aperture size (remember those seemingly random “standard” numbers like F2.8, F5.6, etc.?) is actually the result of a simple formula:
F = f / D
In this equation, f denotes the focal length and D denotes the diameter of the opening (all measurements in millimeters). This may be more clear if you study image 2-1, where the formula is shown applied to a lens.
Image 2-1. Calculating the aperture of a lens.
This formula explains a couple of things. First, it’s the reason why a smaller aperture number indicates a larger aperture—it’s because that D value is the denominator of a fraction. So just as ½ of something is actually a bigger portion than ⅛ of that same thing (even though 2 is a smaller value than 8), F2 is a larger opening than F8.
A second thing we can learn from this has to do with lens construction. Let’s consider a 200mm lens with a maximum aperture of F2.8. If we fill the formula, we get: 2.8 = 200/D. Solving for D reveals that the diameter of the lens opening would be 71.4mm. This means the lens needs to be, physically, over 7cm wide to provide that aperture. What if that 200mm lens had only an F5.6 maximum aperture? That would require an opening of only 3.5cm—and a lens that is half the diameter requires fewer materials to make. This is part of the reason why a “fast” F2.8 lens costs a lot more than a “slow” F5.6 lens.
Image 2-2. The red text shows the spot where I focused, with my zoom lens at 165mm.
When it comes to aperture, the primary concern we need to address is depth of field. Good photographers are able to previsualize how different aperture settings will impact the areas of sharpness/blur in their images—and use that knowledge for creative effect. Images 2-2 to 2-4 show three shots of a Central Park scene. Throughout this series, the focus stayed on the same spot—on the tree near the center of the image—and the focal length remained set to 165mm on a 70–200mm zoom lens. The aperture setting was changed from shot to shot (along with the shutter speed, to maintain an equivalent exposure). Compare the far building and the nearest tree; the differences in their sharpness are very obvious.
Fast Lens
A lens with a very wide maximum aperture. At equivalent light levels, the wider maximum lens opening allows for faster shutter speeds to be used.
Focal Length
The focal length is not a measurement of the actual length of a lens, but a calculation of the distance from where light hits the lens to the point where the light rays converge to form a sharp image on the digital sensor. The focal length also tells us the angle of view. The longer the focal length, the narrower the angle of view; the shorter the focal length, the wider the angle of view.
“Good photographers are able to previsualize how different aperture settings will impact the areas of sharpness/blur in their images.”
Images 2-3 and 2-4. Changing the aperture changes how much of the image is sharply focused.
Setting the Scene, Shaping the Narrative
Knowing that changing the aperture impacts the depth of field, how can we put this to use? Compare images 2-5 and 2-6. Here, wintry foliage is the theme—but the different aperture settings not only affected the composition, they also shifted the narrative. In image 2-5, the blurry skyline keeps the center of attention on the plants. Even among the plants, there is variation in sharpness, creating a sense of depth. Image 2-6 plays up the urban backdrop and emphasizes a recognizable landmark (The Empire State Building) so the setting is no longer anonymous. It is clearly New York City.
Image 2-5. A blurry sky puts the attention on the plants.
Image 2-6. More depth of field brings the skyline into focus and better sets the scene.
Take a walk along a street, in a park, or along a hiking trail. Watch for an interesting combination of still-life subjects that make up a good foreground and background—things that, together, tell a story. For example, an iron gate and the house it leads to, a picket line sign and the protesters, a street performer’s face and the bystanders, or a cactus flower and the vast desert. Compose a shot with the foreground element in the predominant position (at one of the Rule of the Thirds points). Experiment with photographing the same composition using different aperture settings to achieve different depths of field. Also, try focusing on either the foreground or the background and evaluating how this affects your results at different aperture settings.
Back at home, go through the images and select two to four different takes of the same scene. Present them to a group critique or post them on Facebook or Instagram and ask your friends for feedback on their favorites. Watch how the public responds to your picks. As a photographer, you’re not required to please everyone—but it is always good to understand how your own tastes compare to the tastes of viewers.
Let’s look at another case when the choice of depth of field shapes the narrative. Have a look at images 2-7 through 2-9, showing a lamp in Central Park in the foreground and the historic Sam Remo towers in the background. With a shallow depth of field, a simple focus shift from the background to the foreground changes the whole story. In image 2-7, it’s about a high-rise condo complex in the vicinity of a park. In image 2-8, it’s about a park that’s adjacent to a high-end residential area. In image 2-9, I changed the aperture setting to increase the depth of field; now everything is in focus—but honestly, the overall image is less interesting compared to the other two shots.
Image 2-7. The focus is on the background.
Image 2-8. The focus is on the foreground.
Image 2-9. The aperture was adjusted to keep everything in focus.
Image 2-10. Even at the same aperture, the effective depth of field shrinks when your subject is very close to the camera.
Close Up, Depth of Field Shrinks
The choice of depth of field is often a vital factor in how the image informs the viewer. For still-life photography, which often involves close-range focusing, it’s also important to note that the depth of field shrinks when the camera is very close to the subject. Image 2-10 shows this difference. Knowing this characteristic, it is important to set the aperture as small as possible when shooting close to show the intricate details of a still life subject.
Adapting to the Subject and Lighting
What constitutes the “best” or “right” aperture setting will change depending on the subject, the story you want to tell, and the lighting conditions where you’re working.
Images 2-11 and 2-12 show two opposite usages of depth of field. In image 2-11, a deep depth of field (an aperture setting of F16) was used to showcase a plate of ravioli being masterfully decorated by the food stylist. Image 2-12, on the other hand, has a very shallow of depth of field. In this case, however, there wasn’t another choice. The light in the tank was quite dim and the aquarium (like most museums) prohibited shooting from a tripod. My only choice was to open the aperture all the way up to achieve an operable shutter speed that allowed me to hand-hold the camera without worrying too much about blur from camera shake. However, the shallow depth of field suits this composition; the center of focus now remains on the observer and the jellyfish near him. The reduced sharpness and details in the rest of the frame help keep the narrative in a clearer perspective.
Image 2-12. A shallow depth of field suited this composition—and a wide aperture allowed me to use a short enough shutter speed for hand-holding the camera.
Image 2-11. A deep depth of field maintained good sharpness across this beautifully prepared dish.
Image 2-13. F22.
Image 2-14. F4.
Let’s look at another example. Images 2-13 and 2-14 show my dear in-laws’ newly acquired, gold-leafed, Italian handmade chandelier. This fine work of art is 3 feet tall. In order to showcase its fine artisan features, it was important that the depth of field covered the entire chandelier. Shooting at F22 (image 2-13) did a much better job of this than shooting at F4 (image 2-14).
“In order to showcase its fine features, it was important that the depth of field covered the entire chandelier.”
Photographing a small, confined animal (like a bird in a cage or fish in a tank) can be rather challenging. Their smallness calls for close-ups, which comes with the attached complication of inherently shallow depths of field. To counter that, the aperture must be shrunk to maximize the depth of field—which adds another complication: slow shutter speeds. So, we can increase the ISO—but we don’t want to go so high that noise detracts from the image quality! (Did I mention that photography is a business of trade-offs?)
The secret to success is using plenty of light. Move the fish tank or bird cage next to a window (and make sure the cage door is secured, or your birdie might be too tempted by freedom!). Flash is not recommended for birds, as they can get startled by it—but fish seem to be at ease with the sudden flashes of light, so you might consider adding a flash to send light from the opposite side of the tank (more on flash exposure in chapter 5).
Robert Capa said, “If your photos aren’t good enough, you are not close enough.” Shall we photograph something close? For this exercise, choose any subject you want—your favorite bottle of wine, a lava cake, a memorable trophy, a brilliantly decorated Christmas tree ornament, etc. Light the scene well with directional window light, a bounced flash (see chapter 5), or bright ambient light. Simplify the background: a kitchen counter, a plate, or the leaves of a plant would all provide good backgrounds.
Mount your camera on a tripod, so you can shrink the aperture, maintain low ISO, and avoid the motion blur of using long shutter speeds with the camera hand-held. Using a tripod will also be useful for this exercise because you’ll be shooting very close to the subject—and at short shooting distances, even slight camera movements will have a huge impact on the overall composition. The steadiness of a tripod solves both of these problems. For extra assurance, you may also want to trip the shutter release with a cable or remote control, so your pressing finger won’t jar or jiggle the camera.
Adjust your camera to an aperture setting below F11 and position yourself very close to the subject (or zoom in close to frame the subject tightly). Experiment with focusing on various parts of the main subject: the closest spot, the farthest (visible) spot, or a spot in between. Also vary the composition and the lighting. Take many shots of this one subject and work toward refining your results.
Back at the computer, go through these images and look for your favorites. Besides using your gut feeling, also ask yourself questions like, “Which image best showcases the subject’s true appearance?” or “Which image shows the subject in the most aesthetically pleasing way?”
Motion Blur
Softening of details in a photograph due to subject movement or camera movement. This becomes more pronounced at longer shutter speeds.
Cable Release/Remote Control
A device used to trigger the shutter without the photographer making physical contact with the camera. Especially in low-light or close-up photography, with the camera tripod-mounted or otherwise stabilized, this can eliminate camera motion blur and improve image sharpness.
Sensor Dust: Ready to Bite When the Aperture Is Small
While the chandelier in the previous image sequence was beautiful, it was also in some ways a photographer’s nightmare—or, to be exact, a digital photographer’s nightmare. As the insets in image 2-15 show, at tiny apertures like F22, we have to confront the nightmarish reality of sensor dust. Dust particles are attracted by the static of the sensor and eventually some of them end up stuck to the surface of it.
Image 2-15. At F22, dust on the sensor becomes obvious.
Image 2-16. How sensor dust appears at different aperture settings.
Oddly, none of these devilish dots appeared in image 2-13. Why is that? When the aperture is open wide, light comes into the camera from a broad area, striking the dust at various angles and casting a very fuzzy shadow on the sensor. In the case of a very small dust particle, the shadow might not be visible at all. On the other hand, when the aperture is small, the light falls on the dust particle from a narrow area, therefore casting a sharply defined shadow on the sensor. Image 2-16 illustrates how sensor dust appears differently under different aperture settings.
When images are shot at any aperture wider than F5.6, sensor dust is seldom an issue. When the situation calls for a small aperture, however, you can really start to wonder when the sensor was last cleaned. The ability to change lenses is the forte of the DSLR system, but it also provides an opportunity for dust to invade the interior of the camera. This was not an issue with film cameras, because advancing the film naturally swept the dust particles away, so they would not accumulate. DSLR image sensors, on the other hand, not only stay still but generate a static charge that attracts dust. Therefore, it is very important to have DSLRs cleaned professionally from time to time. The more often the lens is changed, the more often the sensor has to be cleaned.
Wondering if your DSLR is loaded with sensor dust? Or due for a clean-up? Try this unusual exercise—one in which a successful outcome is an unpleasant one. Point your camera at a cloudy sky, a piece of white paper, or a computer monitor that is showing nothing but white (a blank Photoshop canvas in full screen mode works). Set the ISO below 800 and select the smallest aperture on your lens. Focus manually, since autofocus doesn’t work well when shooting a textureless, blank subject. Looking through the viewfinder at the meter, adjust your shutter speed so that the image is 2 stops overexposed and shoot. After downloading the image, zoom in to search for traces of dust. If there are none or only a few, congratulations! If you see the dust particles forming a constellation, it is time to visit the camera repair shop for a cleaning.
Portfolio and Practical Examples
Let’s look at a few more images I created with specific depth of field considerations. As discussed in chapter 1, designing an image involves balancing a variety of technical decisions about exposure and creative decisions about how the side effects of each camera setting will impact the presentation of the subject.
Image 2-16—Inescapable Mathematics
This is a play on the hyper-complexity of urban architecture. There are multiple reflections of the buildings intertwined with images through the windows. In the reflections, you can also see the clouds in the sky. To underscore the dazzling complexity, I used a very deep depth of field—so all subjects (direct, reflected, and seen through windows) would be as sharp as possible.
Image 2-17—Holocaust Museum, Houston
Creating separation between a sharply focused subject and an out-of-focus background doesn’t require much effort (in terms of selecting just the right aperture) when there’s a large physical distance between the foreground and the background. That type of arrangement naturally produces the look of a shallow depth of field. The sharply focused part the fence is symbolic of the horrific history, while the modern structure of the museum, softly out of focus, wakes the viewer up from a nightmare.
Images 2-18 and 2-19—Beacon
This is depth of field used to the extreme. While shooting aboard a ferry to the Statue of Liberty, I kept the focus sharply placed on her (as shown in the inset)—even though she represents no more than 2 percent of the whole image. It is that stark contrast of sharpness, size, and color that strongly carries the narrative.
Image 2-20—Self-Portrait
I am fascinated by the intricate details of modern architecture. When photographing Frank Gehry’s Walt Disney Concert Hall, I felt compelled to pose myself with the masterpiece. However, my self-portrait does not follow the in-your-face feeling of a Cindy Sherman self-portrait. I preferred to remain behind the scenes, so I used a depth of field that showcases the building in sharp focus—both through the window and reflected by the window—and integrates the image of me as a softer form, beyond the depth of field yet clearly holding a camera. This reflects (pun intended) my moderate level of narcissism.
Images 2-21 and 2-22—The Bridge
Here we see the First Calvary Cemetery in Queens, New York—with Kosciusko Bridge in the background. This image’s horizontal divider divides the far/near, busy/quiet, steely/stony, and living/dead. In order to convey this narrative, I used a telephoto lens to narrow the field of view and ensure the distant bridge remained large. If I’d shot with a wide-angle lens, I’d have needed to move in closer to capture the headstones at a similar size, and the bridge would have looked much smaller. As a result, the intended narrative would have been lost. The infinity focus setting on a telephoto lens is also more distant than on a normal or wide-angle lens, making it easier to control the depth of field with far-off subjects. This is illustrated in the accompanying diagram.
Image 2-23—Crow of Bryce Canyon
I photographed this crow at close range. Even with the lens wide open (at F4) a shallow depth of field is hard to achieve on the 17–35mm super wide-angle zoom. Here, however, the close subject and distant background combined to make it work—and the blurred background keeps the spotlight on the crow. This shot would definitely have been easier to shoot from a farther distance with a telephoto lens. But consider the background; the narrow angle of view of a telephoto lens would have incorporated much less of the canyon and sky and diminished the narrative of a bird enjoying its limitless domain. Any second now, it could take off and soar. (Here’s my tip for photographing a bird at a closer distance: Point the camera at the bird and shoot while approaching at a calm pace. This avoids having the bird fly away before you’ve even grabbed a single shot—and the camera is up so you’re ready to snatch a shot the moment the bird does decide to take off.)
1. Do you find the uniqueness in every individual? Some quality in that person that just isn’t shared with his or her peers, family members, or community? Can you portray this observation with your camera? Think about this project as a rebuttal to the everyday group shots, using depth of field as a technical vehicle.
2. Many of us like to take “I was here” types of travel photos. “Here I am smiling and making a peace sign in front of the Eiffel Tower!” “Here I am smiling and making a peace sign in front of The Great Wall of China!” “Here I am smiling and making a peace sign in front of Yellowstone’s Old Faithful.” When these photos are presented together in an album or on social media, your viewers naturally tend to get bored. Can you figure out a way to photograph your journey more artistically? Is there a different way to provide empirical evidence of your presence at these landmarks—without showing your face in the photos? Your face is not the only aspect of your personal identity that can be photographed. (And, of course, the topic of this chapter is also a hint.)
3. Are you taking a photo of the dish you are about to dig into? Wait! If you’ve always thought about showing your face at the places you visit, why wouldn’t you prove that it was you who ate this dish? The tablecloth is not the only possible background for a food photo.