Prime Lenses

Figure 10.5 Wide-angle lenses are often used to capture broad vistas, yielding images such as this one.

Source: Chris Walker.

Lenses with a single focal length are called prime or fixed focal-length lenses. With a fixed focal-length lens, the only way to affect angle of view is to physically change the distance between the camera and the subject. Serious photographers often own an assortment of prime lenses with a variety of focal lengths, enabling them to manipulate angle of view by simply swapping out the lens. Prime lenses are often classified into one of five main categories: wide-angle, telephoto, normal, novelty (macro and fisheye), and super-telephoto.

• ■ Wide-angle lenses have a relatively short focal length (18–35 mm for full frame, 12–24 mm for APS-C [Advanced Photo System Type-C]) resulting in the wide angle of view. Wide-angle lenses, or short lenses as they’re sometimes called, are often used for shooting landscape panoramas and vistas where the primary emphasis is on establishing a wide overview of the scene (see Figure 10.5).
• ■ Telephoto lenses have a long focal length (90–300 mm for full frame, 60–200 mm for APS-C) resulting in a very narrow angle of view. Telephoto lenses, or longlenses, can magnify distant objects, making them appear much closer than they really are (see Figure 10.6, left). These are the favorite lenses of bird watchers, sports photographers, and naturalists for obtaining close-up shots of a subject from a distance.
• ■ Normal lenses have a medium focal length (40–60 mm for full frame, 28–40 mm for APS-C) resulting in an angle of view that falls somewhere in between the extremes of wide-angle and telephoto. Normal lenses are a safe bet for general-purpose shooting activities that do not require extreme close-ups or wide shots of the subject matter.
• ■ Novelty lenses have descriptive names like macro and fisheye and feature unique optical characteristics designed for atypical shooting situations.
  • ■ Macro lenses can acquire focus when positioned only a few inches away from the subject. Macro lenses produce high-quality images with low image distortion and are useful for shooting extreme close-ups of small objects like insects or flower blossoms (see Figure 10.6, right).
  • ■ Fisheye lenses have an extremely short focal length (8–15 mm for full frame, 11 mm or less for APS-C), offering an angle of view as high as 180 degrees. However, because of the extreme curvature of glass, images acquired with a fisheye lens are significantly distorted, which results in an interesting hall of mirrors–type effect.

• ■ Super-telephoto lenses (400–600 mm for full frame) yield the narrowest angle of view while offering extremely high levels of image magnification.

Figure 10.6 Because of their magnification, telephotos and macros are more likely than other lenses to add camera shake to your image. To help avoid this, a good starting point is to convert the lens’ focal length into a fraction and use that as a shutter speed—a 200 mm lens would become 1/200th, so it should be handheld at 1/250th or faster.

Source: Chris Walker.

Zoom Lenses

A zoom, or variable focal-length lens, can be adjusted to any focal length within a set optical range. For example, using a zoom lens with a range of 28–300 mm, the focal length can be set to wide-angle (28 mm), telephoto (300 mm), or anywhere in between. Zoom lenses allow the photographer to quickly change the angle of view without having to swap out the lens. With this type of lens, the photographer zooms in to acquire a narrow angle of view and zooms out to compose a wide shot. The zoom ratio indicates the magnification capability of a variable focal-length lens. For example, a 3× or 3:1 zoom ratio means the size of the image at the longest focal length setting (telephoto) is three times greater than the size of the image at the shortest setting (wide-angle). High-quality zoom lenses are very expensive. While their optical quality is generally inferior to that of prime lenses, the speed and convenience of zooming can be a worthwhile tradeoff. Zoom lenses are included on most point-and-shoot still cameras as well as on all consumer, prosumer, and professional video cameras.

Sensor Size

For years, 35 mm reigned as one of the most popular photographic film formats for SLR (single lens reflex) cameras, both for amateurs and professional photographers alike. The physical dimensions of a 35 mm film frame are 36 × 24 mm. As manufacturers began developing digital cameras, they adopted these dimensions as a baseline measure by which to conform and compare the physical size of electronic image sensors. A full-frame image sensor is so named because it perfectly mirrors the dimensions of 35 mm film (36 × 24 mm). Professional DSLRs almost always use a full-frame sensor or a variant of the Advanced Photo System Type-C format. APS-C sensors are considerably smaller than full-frame sensors and vary slightly in size by manufacturer and camera model. Cheaper DSLRs, compacts, and smartphone cameras are equipped with progressively smaller sensors. As a rule, the smaller the camera is, the smaller the image sensor will be. For example, the iPhone 6, released in 2014, uses a one-third-inch sensor that measures a mere 4.80 × 3.60 mm (see Figure 10.9).

Figure 10.9 The one-third-inch image sensor built into Apple’s iSight camera (iPhone 5/6) is extremely small in comparison to the full-frame sensor of a Nikon D3X and the APS-C sensor of the less expensive Canon 70D. Typically, the larger the image sensor the more expensive and higher quality the camera is likely to be.

Tech Talk

Focal Length Multiplier The size of the image sensor determines the angle of view that can be achieved with any particular lens. All things being equal, larger sensors offer a wider angle of view than smaller ones. If you attach a lens designed for 35 mm film to anything other than a full-frame DSLR, you will observe a noticeable difference in the angle of view when shooting with an equivalent focal length. How much of a difference? It depends on the focal length multiplier. The terms crop factor and focal length multiplier (FLM) are interchangeable terms and concepts that were developed to help photographers quantify the effects of using full-frame lenses with APS-C sensors.

Table 10.1 The Relationship of Focal Length to Angle of View

Lens Type	Focal Length, Full Frame/APS-C	Angle of View
Fisheye	8–15mm/less than 11mm	Up to 180°
Wide-Angle	18–35mm/12–24mm	90° to 54°
Normal	40–60mm/28–40mm	48° to 33°
Telephoto	70–300mm/60–200mm	28° to 7°
Super-Telephoto	Greater than 400mm/200mm	6° to 4°

If you were to use a full-frame lens on an APS-C format camera set to the same focal length, the resulting image would appear cropped, thus producing a narrower angle of view. As an example, a normal lens for a full-frame camera is usually a 50 mm, while a normal lens for an APS-C format DSLR is around a 35 mm. This difference in performance is the focal length multiplier (FLM). Most prosumer cameras have an FLM between 1.4 and 1.6. To use the FLM, multiply the lens’ actual focal length by the FLM to see what its full-frame equivalent would be. In the prior example, a 35 mm lens on a camera with a 1.4 FLM is the same as a 49 mm (essentially a 50 mm) lens on a full-frame camera.

By conforming the full-frame sensor dimensions to 35mm film, manufacturers saved professional photographers a considerable amount of angst. They would not be forced to retire their inventory of perfectly good lenses when transitioning to a digital camera body or have to modify their composition techniques because trusted lenses no longer performed as expected.

Figure 10.10 In this image, the lens used to make the original 4 × 5” version was a 90 mm, which translates to wide-angle on a large-format camera. But as the highlighted boxes illustrate, that same lens would render a “normal” angle of view when attached to a medium format camera and a close-up view when used on a DSLR.

Source: Chris Walker.

Image Resolution

The resolution of a digital camera or still image is determined by how many pixels the image sensor can produce. For example, the Canon PowerShot G16 is a 12-megapixel camera that, when set to its highest resolution, can produce a 4000 × 3000 pixel image. This is called native resolution because the camera is using all the pixels on the image sensor to produce the image. As the photographer, you can change the capture settings to a lower resolution such as 1600 × 1200 or 640 × 480. In response, the camera will use only a designated portion of the pixel array to form the image.

Image Encoding and Compression

On consumer cameras, images are recorded using the popular JPEG compression codec. JPEG compression reduces the amount of space required to record an image to the memory card as well as the time it takes for the camera to process sensory data once the picture is snapped. Prosumer and professional cameras also support JPEG encoding, but both usually also provide the option of saving images in uncompressed formats like TIFF or Camera RAW. While these formats produce files that are significantly larger, they offer the advantage of preserving most or all of the original sensor data.

The Camera RAW format records a completely unprocessed version of the image as obtained by the sensor at the point of exposure. Professional photographers prefer the RAW file format because it allows them to retain maximum control of image processing during editing. JPEG and TIFF formatted files are processed prior to encoding, limiting the type of adjustments that can be made in image editing. Camera RAW is a proprietary standard that requires special software or plug-ins from the camera manufacturer in order to edit the image. While Camera RAW is a technically superior format, TIFF and JPEG images are much easier to work with, and their quality is acceptable for the vast majority of multimedia applications.

While the number of options varies by model and manufacturer, most digital cameras allow you to specify the amount of compression you want to apply to a JPEG image. For example, Canon offers three choices called normal, fine, and superfine. As the name implies, superfine produces the highest quality image by applying the smallest amount of compression. There’s a dramatic difference between the file size of an image acquired at the smallest resolution and lowest quality JPEG setting and those at the highest quality setting. For example, if you take a picture with Canon EOS Rebel XS set to its lowest resolution (1936 × 1288) and JPEG setting, the resulting image file will be around 700 KB. The same image taken with the camera set to midrange resolution (2816 × 1880) and medium JPEG setting would yield a file of around 1.2 MB. If you were to use the highest resolution (3888 × 2592) and JPEG setting, the file would be around 3.8 MB. Switching the high-resolution setting to RAW bumps the file size up to almost 10 MB. As you can see, it’s important to pay attention to the settings you use. Keeping a camera set to the highest resolution and best JPEG setting is normally a good choice, although using RAW offers advanced users more flexibility. See Figure 9.14 in the “Graphics” chapter for another example of how changing the resolution and JPEG setting affects image file size and the total number of images a memory card can store.

Flashback

The Decisive Moment

For photographers who work on location, the two most important factors in image making are being there and knowing how to capitalize on the situation once you are. In terms of timing, Magnum photographer/founder Henri Cartier-Bresson (1908–2004), considered by many to be the father of photojournalism, believed in the latter with such conviction that he revived the term “the decisive moment” from the writings of a 17th-century French cardinal.

Photographically, the decisive moment is that instant when an action is at its peak, when it’s stronger than it was the moment before or will be the moment after; it’s that singular, perfect, narrow window of time in which the shutter should be released to best depict the emotion of an event. The strength of this moment can be seen through anticipation, through the alignment of compositional elements, or in peak action (see Figure 10.11).

Figure 10.11 In this set of images, the photographer came upon a couple at a county fair who were arguing. In the first of the 10 photographs (not shown) the young man is yelling at his girlfriend, who’d disappeared for an hour. In the final frame, the couple kissed. The first images held more aggression than desired, and the final seemed overtly sappy, so the ninth image, which held the anticipation of making up, became the chosen photograph in the sequence.

Source: Chris Walker.

It took more than 100 years of photography for the term to be needed, but less than half that for it to become obsolete. In the early years of photography, images were exposed over a period of minutes—so timing was far less important than the photographer’s location and composition were. Today we find that technology—the force that, through faster shutter speeds, once created the need for Bresson’s statement—has brought us to a point in history where photographers no longer need to exercise such decisiveness in their timing.

Through the ability to extract still images from video, we will soon be freed from the necessity of precision timing, from the need to depress the shutter at the precise moment an action is at its zenith. Almost as retribution, though, we must now further challenge ourselves to be even more decisive in our selection of focal length, depth of field, and composition.

by Chris Walker

Evaluative Metering Mode

With evaluative metering, the camera samples the intensity of light at multiple points in the image matrix and then combines the results with other camera data to determine the best exposure setting. Evaluative metering is the default method used on most cameras because it produces the best overall results, especially for scenes that are unevenly lit.

Center-Weighted Metering Mode

Center-weighted metering is identical to the evaluative mode except that more weight is given to data from the center of the image when calculating the exposure settings. This method is recommended for scenes in which the main subject is backlit or surrounded by bright background objects.

Spot Metering Mode

With spot metering, the camera calculates exposure based on the light intensity of the main subject located in the center of the screen. Spot metering is best for high-contrast scenes with varying levels of brightness.

Great Ideas

Flash Control

Using the flash allows you to provide additional fill light for scenes where existing lighting is less than ideal. The range of a flash varies by manufacturer, but most are designed to work within 15 feet of the camera. Be careful when using a flash as it may wash out your image. Don’t use a flash unless you really need it. Many cameras allow you to change the output of a flash incrementally from 100% (full), to 75%, 50%, 25%, and off. This feature is helpful when you want to remain close to the subject without overexposing the image or momentarily blinding your subjects. With most cameras, you normally have the option of selecting from a number of different flash modes.

• ■ Fill flash (always on): In this mode, the camera fires the flash every time, even when the exposure meter indicates a sufficient level of natural light. Using a fill flash outdoors on a sunny day can help compensate for excessively bright sunlight, harsh shadows, and uneven backlighting (see Figure 10.15).
• ■ Auto flash: In this mode, the camera meters the available light and only fires the flash when needed. Limiting the use of the flash helps conserve battery power.
• ■ Red-eye reduction: In this mode, the red eyes caused by the reflection of the flash off the retina of the eye is reduced. When the flash is set to red-eye reduction mode, the camera fires a short burst of light followed by the actual flash. The short burst is intended to shut down the pupil of the eye, thus minimizing the kickback of reflected light. The closer the flash is to the lens, the more prone a camera is to producing red-eye. On professional cameras, the flash is farther away from the lens than on built-in systems and can often be detached and repositioned. In addition to controlling red-eye with the flash, you may also be able to reduce it by using a wide-angle lens, increasing the amount of existing lighting, or by moving the camera closer to the subject. In a worst-case scenario, you may be able to remove it using photo-editing software.

Figure 10.15 Images made in direct sunlight can often benefit from a little judicious fill flash. The objective of using fill flash is to “fill” in the shadowed areas that may be too dark without it. Using too much fill, though, can unnaturally set your subject apart from the background. A good starting point is to set your flash to −1. If you’re using a non-dedicated unit, try setting the ISO to a higher setting—either way, the flash will get the message that you desire less light on your scene than what it might want to give you.

Source: Chris Walker.

Aperture

On professional lenses, the aperture is adjusted by turning the innermost ring on the outside of the lens housing. A series of f-stop numbers are printed on the outside surface of the ring, indicating the size of the aperture. While shown as a whole number, an f-stop unit is actually a fraction used for calculating the physical diameter of the aperture. For example, an f-stop setting of f/16 means the diameter of the aperture is equal to 1/16th the focal length of the lens (see Table 10.2). To calculate the aperture of a 50 mm lens set to f/16, you would use the following formula:

Typical f-stop positions include: f/32, f/22, f/16, f/11, f/8, f/5.6, f/4, f/2.8, f/2, and f/1.4, although you typically won’t find a single lens that covers the entire range. Because the f-stop number is a fraction, the size of the aperture actually decreases as the f-stop number increases.

Opening the aperture by one full f-stop (e.g., changing from f/11 to f/8) doubles the size of the aperture and the amount of light striking the image sensor. Likewise, closing the aperture by one full stop (e.g., changing from f/1.4 to f/2) reduces the size of the aperture and the amount of incoming light by half. Some lenses allow the aperture to be adjusted in half-stop or third-stop increments for even greater control of light exposure.

Aperture strongly influences the relative amount of depth of field in a shot. To achieve shallow depth of field, use a low f-stop setting (wide aperture requires less light). To achieve great depth of field in a shot, use a higher f-stop setting (smaller opening requires more light).

ISO

One of the challenges of digital photography is that much of the terminology is rooted in film. One of the best examples of this is the continued use of the ISO Film Speed system. Originally based on a film’s ability to respond to light, the ISO rating is now used to describe a sensor’s ability to respond to light. The ISO designation follows a logarithmic scale, which means that each jump to a higher ISO number results in a doubling of the film’s light sensitivity (see Table 10.3). This corresponds nicely to the f-stop scale, which works in precisely the same manner. All things being equal, increasing film speed by one ISO level has the same effect on exposure as opening the aperture by one full stop. As film speed increases, however, the sharpness and clarity of an image decreases, and your image will have a grainier, or “noisier,” appearance (see Figure 10.17). For the cleanest images, it’s best to shoot with the lowest possible film speed setting. Unless you choose to manually override the ISO setting of the camera, your camera will usually set your film speed automatically based on lighting conditions, flash settings, and other selected exposure settings.

Figure 10.17 Electronic and analog media share many characteristics, including the degradation of image quality at higher ISOs. As the enlarged view illustrates, the discrepancies between ISOs 200 and 3200 are quite apparent. As technological improvements continue to be made, the distance in quality between low and high ISOs continues to shorten.

Source: Chris Walker.

Shutter Speed

Shutter speed influences how motion is captured by the image sensor. Use slower shutter speed when subject motion is minimal, the light level is low, or you purposely want to create a motion blur effect (see Figure 10.18). Use a faster shutter speed when shooting fast-moving subjects, in settings with plenty of light, or when purposely trying to freeze action without compromising image clarity.

Figure 10.18 A motion blur was achieved in this image by following the taxi cab in motion using a slow shutter speed.

AF Target Point

By default, autofocus is usually set to a single target point located in the center of the image. When the main subject is positioned in the center of the frame, this works well. Simply set the focus and snap the image. However, a different focusing strategy must be employed when the subject is placed in an off-center position. With most cameras, this involves the following steps: 1) place the main subject in the center of the screen; 2) acquire and lock the focus by depressing the shutter button halfway; 3) reframe the main subject in an off-center position; and 4) fully depress the shutter button to capture the image. Many cameras provide options for acquiring focus with user-select, single-spot, or multi-spot target points.

While active and passive autofocusing systems have improved dramatically over the years, neither method is foolproof. At some point, autofocus will let you down as the camera miscalculates the proper focus setting. Problems are likely to occur in the following situations:

• ■ When near and distant objects are mixed close together within the frame, the camera may be unable to determine which object in the composition to focus on.
• ■ Moving objects like cars and bikes can confuse the autofocus sensor, causing a focus shift at the point of acquisition.
• ■ Extremely bright lights or subject areas can make it difficult for the camera to lock onto a subject and acquire focus.
• ■ Monochromatic scenes can lack the contrast necessary for acquiring an accurate focus.

Fully Automatic Mode

When set to fully automatic mode, a camera will analyze the area of a scene and calculate the settings for shutter speed, aperture, ISO, white balance, focus, and flash. Depending on the quality of the camera, shooting in auto mode can produce good results under normal lighting conditions most of the time. While shooting in auto mode makes the camera easier to operate, it significantly reduces the photographer’s role in the creative process.

Figure 10.23 On many DSLRs, the exposure mode can be quickly changed using a rotating dial such as this on the top of the camera.

Portrait Mode

In portrait mode, the exposure controls of the camera are optimized for shooting close-ups with a shallow depth of field. The objective in this mode is to keep the subject in focus while blurring the background. The camera accomplishes this by raising the shutter speed in conjunction with widening the aperture. Portrait mode works best when the subject is tightly framed and there is considerable distance between the subject and the background. Shallow DOF is always more difficult to achieve when the subject is placed directly against the background.

Landscape Mode

Landscape mode is the opposite of portrait mode. In this mode, the exposure settings of the camera are optimized for shooting wide shots with a great depth of field. The objective in landscape mode is to keep as much of the scene as possible in focus. To accomplish this, the camera combines a small aperture with a slower shutter speed. As a result, in some cases, you may need to use a tripod to maintain a steady shot.

Sports Mode

Sports mode, or action mode, as it’s sometimes called, favors a fast shutter speed and is recommended for shooting a moving subject within a scene. When capturing moving subjects during a bike race or soccer game, for example, a fast shutter speed is required in order to freeze the image without blurring. If the shutter speed is too slow, a motion blur will occur. When composing an action scene, a dramatic effect can be achieved by panning the camera along with the moving subject while depressing the shutter button. This technique produces a sharply defined subject while creating an intentional motion blur in the background (see Figure 10.24).

Figure 10.24 Sports mode is useful for stopping action and having enough depth of field left to make your images sharp. But sometimes it’s good to experiment and “pan” a few frames. Panning is the process of selecting a slow shutter speed, such as 1/8th or 1/15th, and triggering the shutter while following the action. This method is not for the impatient; photographers who succeed at panning learn early on to shoot hard and edit harder.

Source: Chris Walker.

Night Mode

Night mode uses a slow shutter speed combined with the flash when shooting a subject set against a dimly lit backdrop like a sunset or evening sky. The long exposure time allows the details of the background to remain correctly exposed during the firing of the flash to illuminate the subject. A tripod should be used in order to prevent unintentional blurring.

Tech Talk

Stitching Mode Stitching mode is used for acquiring a sequence of shots that can be joined together in editing to create a high-resolution segmented panorama (see Figure 10.25). After taking the first picture in stitch mode, the camera provides a split screen view of the previous shot and the currently framed scene to help you align the end of one frame with the beginning of the next. Many smartphone cameras and compacts offer a panorama mode to achieve a similar outcome. Instead of shooting multiple segmented images of a scene and stitching them together later in editing, your camera creates a single image on the fly as you pan slowly across the scene during exposure. Shooting in panorama mode is easy and can produce good results under the right conditions. However, it isn’t really the same thing and can often lead to unintended visual artifacts. When done well, stitching produces more professional results without visual artifacts because much more original image data goes into the formation of the panorama.

Figure 10.25 Stitching mode can be used to take a series of photos that will be loaded into Photoshop, or an internal camera program, to “stitch” them together. The key to success lies in overlapping your images—between a third and a half of the area of the previous—so the computer can read the design of one image as it prepares to lace it together with the next one in the series. This stitched image, a tiny courtroom where Lincoln practiced law, is a composite of six vertical photos.

Source: Chris Walker.

Aperture Priority Mode

In aperture priority mode, the photographer determines the f-stop setting manually while the camera sets the remaining exposure variables. The main purpose of using this mode is to control for depth of field in a scene. However, unlike portrait or landscape modes, the photographer retains total control of the aperture.

Shutter Priority Mode

In shutter priority mode, the photographer sets the shutter speed while the camera sets all the remaining exposure variables. This mode is used when the photographer wants to retain precise control of exposure time. For example, when shooting a waterfall, a slow shutter speed can be set in order to accentuate motion by blurring the water while the surrounding area of the scene remains sharp (see Figures 10.26 – 10.28). Using a fast shutter speed on the same scene can result in the effect of suspended droplets of water hovering in midair for heightened effect.

Program Mode

Some cameras offer a program mode setting in which the camera determines the correct settings for aperture and shutter speed while allowing the photographer access to other controls like ISO, white balance, flash, and so on.

Renaming Images

Digital cameras usually assign rather meaningless names to image files. Renaming your image files is one of the first and most important things you can do to bring a sense of order and uniformity to a collection of related images. Programs such as Adobe Bridge and Apple’s Aperture can help automate this process. When you rename the files, consider using a standard prefix for related images. For example, for a group of photos taken of Beth on her birthday in 2006, you could use beth_ bd06_ as the prefix. As discussed in chapter 7, “Web Design,” use lowercase names if you plan to use the images online. Similarly, use an underscore instead of a space when you want to separate the character elements in a file name. After establishing the prefix, you need to make the remaining part of the file names sequential. This is where using a program to automate the process really helps. In some cases, you may be able to use part of the file name generated by the camera. This is very helpful for preserving the chronological order of the collection.

Image Folders

Try to avoid the habit of storing all your digital images in a single master folder. As your image library grows, the folder will swell, and it will become increasingly difficult for you to navigate such a large collection of files in one location. A better method is to use subfolders to store related sets of images. Some of the same naming strategies we’ve discussed so far can be applied to the naming of image sub-folders. Sorting images into subfolders according to project or client name, subject name, or event title will help alleviate a great deal of confusion and expedite locating image assets.