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Lenses and Lens Operation

The lens of your camcorder will probably have more of an impact on picture quality, and your control of it, than any other single feature.

Lens Terminology and Functions

Camcorder lenses come in various focal lengths: wide angle, normal, and telephoto. These terms refer to how close the lenses make objects appear in the frame. Wide-angle lenses include a wider field of view than normal lenses and make objects seem far away. Telephoto lenses give a narrower picture and make objects seem close.

FOCAL LENGTH: Range of distances over which a lens can be focused to achieve a sharp picture.

Removable vs. Built-in Lenses

Most consumer and some prosumer camcorders have built-in, nonremovable lenses. Almost all professional models (and some prosumer units) are designed for removable, interchangeable lenses.

For more information on lens selection, see “Ten Ways to Shoot a Chair” in Chapter 5 and on the DVD.

An inexpensive consumer camcorder with a built-in zoom lens could be perfect for shooting news style, since you'll rarely have time to change lenses anyway. Even if you have a professional camcorder with interchangeable lenses, you'll probably rely mostly on a single, multi-purpose zoom lens for news-style shooting. (Of course, the zoom lens on a professional camcorder is likely to be of much higher optical quality than the one on an inexpensive consumer unit.)

If you're shooting film style, there's ample time to change lenses and pick exactly the right one, even though prosumer and professional camcorders generally come with a zoom lens as standard equipment. Lenses are precision instruments, and selecting the right lens is like picking a wrench to do a delicate auto repair: you'll do a better job using the just-right-sized tool than an adjustable one. (There's also a creative dimension to selecting lenses, much like picking a brush of a particular size for the next stroke of your painting.)

Since film-style videographers like to be able to choose just the right lens for each shot, the single most desired camcorder feature for this group is a large selection of removable lenses (Figure 4.5).

Figure 4.5. The XL1S offers an assortment of interchangeable zoom and special-purpose lenses. If you're shooting film style, this is an essential factor in choosing a camcorder. (Photo courtesy Canon U.S.A., Inc.)

Exposure and Focus

Getting good exposures isn't just a matter of setting your camera correctly; how you light a scene is extremely important. But the camcorder certainly plays a role. The main way of controlling exposure on the camcorder is to adjust the aperture, iris, lens opening, or f-stop—all of which mean the same thing.

APERTURE: Size of lens opening used to control exposure; iris.

F-STOP: A numeric index defining aperture size. Camcorder f-stop settings generally range from f/1.6 (the widest opening, allowing the most amount of light to enter the lens) to f/16 (narrowest opening, least light).

MONITOR: External display connected to a camcorder that shows the viewfinder image on a larger screen so you can frame the shot and judge its quality.

The iris can open or close to a specific aperture size or f-stop. On some photographic-style lenses, you select f-stop settings by rotating a ring on the lens barrel. On other camcorders, you rotate a dial, or iris wheel, on the camera body. On most camcorders, the current setting appears in the viewfinder and monitor status displays (Figure 4.6).

Figure 4.6. The alphanumeric status display shows the camcorder's current f-stop setting, among many other things.

The higher the f-stop number, the smaller the aperture, and the less light striking the CCDs. (For instance, f/2.8 is a large opening that lets in more light than f/16, which is a small opening.) The ideal setting, whether you're shooting video or film, will be in the midrange between f/4.0 and f/5.6—called the “sweet spot.”

Video CCDs respond best between f/1.6 and f/11. F/1.6 is the widest aperture for low-light conditions, and f/11 is about the smallest, for bright lighting. (If you need a setting outside this range, you'll need to adjust light levels instead.)


You may see t-stop settings listed in lens spec sheets. T-stops are numeric indexes for the actual performance of a specific lens. You needn't concern yourself with t-stops unless you are comparison-shopping for lenses for a special purpose, such as shooting in low light. T-stop indexes work like f-stops: Larger numbers mean smaller openings.

Most camcorders have an auto-exposure (AE) feature. If you're serious about the quality of your work, you will turn it off and set exposures manually. Even so, some consumer-level camcorders don't give you full control over the exposure. They set the exposure for you and then allow you to open or close the iris by only one or two f-stops. This feature is usually called AE shift. Stay away from cameras with this feature if you want true manual operation. (For more information on using a light meter to set correct exposures, see “Light for Narrow Contrast Range” in Chapter 6.)

Focusing is what makes the picture sharp (or fuzzy, if you do it wrong—or if you're going for a slightly soft look to hide the star's wrinkles). On almost all camcorder lenses, you adjust focus by rotating a focus ring, a circular fitting that wraps around the barrel of the lens (Figure 4.7). Some inexpensive still cameras come with fixed-focus lenses that can't be adjusted, but you won't find them on camcorders. However, some palm- and pocket-sized camcorders with lenses built into the body can be focused manually only by disabling the camera's autofocus feature.

Figure 4.7. The barrel of the telephoto zoom lens on the XL1S has two knurled, black, moveable rings. The ring closest to the operator controls zoom; the one farthest forward controls focus. Notice that (unlike photographic-style lenses) this lens has no distance markings on the rings. However, the current distance setting appears in the alphanumeric viewfinder display. (Photo courtesy Canon U.S.A., Inc.)

AE SHIFT Semi-automatic camcorder function that you adjust one or two f-stops up or down from the setting calculated by the camera's autoexposure circuit.


Want to make sure your shot is in focus? Zoom in on your subject as close as you can go. Adjust focus until the image in the viewfinder is sharp. Now, readjust the zoom to frame the shot you want. The shot will be in focus anywhere within the zoom range.

How Lens Aperture Affects Depth of Field

Depth of field defines the range of distances that will remain in focus within a single shot. For example, in a medium shot with a normal lens, objects three to six feet away might appear sharp. Objects nearer than three feet and farther away than six will be blurred. Telephoto lenses tend to have a shallower depth of field (a narrow range of distance can be in focus), and wide-angle lenses tend to have a greater depth of field (nearly everything in focus).

In any case, setting depth of field is an important artistic decision, part of composing a good shot. But it's not just a matter of changing lenses. The size of the aperture makes a big difference: Smaller f-stop settings (say, around f/11) will give greater depth of field than larger apertures (for instance, f/1.6). In addition, dim lighting gives shallower depth of field than bright. (We've summarized these factors in Table 4.1.)

Table 4.1. Factors Affecting Depth of Field
Depth of FieldLens Focal LengthApertureLighting Level
ShallowTelephotoWide openDim
GreatWide angleStopped downBright

The focal length of your lens, the size of your aperture, and the level of lighting all affect depth of field. However, apparent differences in depth of field will be more pronounced on film than on video, because video cameras tend to put almost everything in focus. (For more information on depth of field and optical target size, see the sidebar “Making Video Look Like Film” in Chapter 3.)


When used for closeups, long lenses (with shallow depth of field) not only flatter the face, but can also direct audience attention to the actor's eyes. In this type of setup, the depth of field can be so shallow that one eye will be in focus, leaving the ear and the hair soft. Due to video's inherently greater depth of field than film, this effect has been more typical of movies shot on film.

Additional Camcorder Settings

You may encounter some other types of features and settings that can affect exposure.

Shutter Speed

You may be familiar with what shutter speed does in still photography. Don't expect adjusting this control on a movie camera does the same thing; and once you've come to terms with what shutter speed means in a motion picture context, forget that too: Neither still photography nor movie photography will prepare you for how shutter speed works in videography.

In a still camera, adjusting the shutter speed changes how long the shutter is open. High shutter speeds mean shorter exposures, which freeze motion better. They also reduce light levels, which means you need to open the aperture wider to let in more light. Simple.

SHUTTER SPEED (STILL PHOTOGRAPHY): Varies length of time film is exposed to light.

SHUTTER SPEED (MOTION-PICTURE CAMERA): Varies the frame rate (fps).

SHUTTER SPEED (VIDEO CAMCORDER): Varies length of time CCDs are exposed to light during each frame; does not affect the frame rate.

In a motion-picture film camera, shutter speed controls the number of frames the camera captures each second. Increasing the shutter speed means you're recording more than the normal 24 frames per second, which achieves a slow-motion effect when the film is projected at normal speed.


To study how varying the frame rate in a motion picture camera can affect the perception of fast-moving action, take a look at the opening fight scene in Gangs of New York. For example, to emphasize the reactions to blows rather than the impacts, follow-through motions have a horrifying, staccato quality. To achieve similar effects in video, you might have to experiment with varying both the shutter speed and the shutter angle (discussed in the next section). If creative motion effects are your goal, you'll need to select a camcorder that offers these controls.

Few video camcorders, consumer or professional, can shoot true slow motion. Their frame rates are fixed by their television standard—NTSC (30 fps) or PAL (25 fps). (Slo-mo effects are typically done in post.) A shutter-speed control, if one is available, only regulates the length of time the image of each frame stays on the CCD, much like a still camera.

SLO-MO: Slang for “slow motion.”


An HD vidcam that can shoot slow motion (indeed, a range of variable frame rates) is the Panasonic AK-HC900.

Adjusting the shutter speed on a video camcorder does have a striking effect, and it will allow you to fine-tune the look of moving objects in your video. At some shutter speeds motion appears jerky, at others erratic, and at some settings, motion looks smooth as silk.

For instance, in interlaced scanning mode, a camcorder shutter normally operates at 1/60—one exposure for each field. Changing it to 1/30, a longer duration (one exposure per frame), might make moving objects look blurred. Changing to a higher shutter speed, such as 1/200, might make the action go by in fits and starts when you play it back.

If you adjust the shutter speed, you must also adjust the aperture to expose the scene correctly. This is true for all three imaging methods: still photography, motion-picture photography, and videography.

Shutter Angle

Movie cameras have a control called shutter angle, which affects the physical orientation of the rotating mechanical shutter to the film. Since most camcorders don't have mechanical shutters, it probably seems odd that some of them offer a shutter-angle control.

SHUTTER ANGLE: Vidcam setting that emulates the staccato-motion effect of varying the physical angle of a motion-picture camera shutter.

The effect of adjusting shutter angle is much the same in film and video: it changes the appearance of motion on the screen. It's an unpredictable effect, and you'll need to experiment with it to see what it looks like.

Reducing the shutter angle reduces both the amount of light and the length of time each frame is exposed, making action appear more jumpy. Videographers sometimes reduce shutter angle by increments of 45º or 90º when they want to make action seem more intense. However, at some settings the scene may flicker badly because artificial light sources actually pulsate with the frequency of electrical power.

An excellent example of the aesthetic effect that shutter angle creates can be seen in the combat scenes of Saving Private Ryan. These scenes were shot with a different shutter angle from the rest of the film, giving them the feeling of an altered sense of reality.

Video Gain

At low-light levels, as in a room lit only by a flashlight, video camcorders have an advantage over film cameras: they can increase their sensitivity to light. One way to accomplish this is to increase the excitation, or bias voltage, applied to the CCD itself; some cameras do this automatically. (For more information, see the sidebar “CCDs in Low-Light Conditions,” in Chapter 3.) Another way is to manually turn up the video gain, or electronic amplification of the signals coming from the CCD. Both methods have the same effect.

VIDEO GAIN: Degree of amplification of CCD output, measured in decibels.

Either way, the cost is video noise, a fuzzy-picture quality much like the grainy quality film gets when underexposed. (Some videographers like the effect, but your client might just think you don't know how to light a scene.) Many camcorders feature automatic gain control (AGC). Make sure you can turn it off; in some less expensive models, you can't.


Don't confuse video AGC with its audio counterpart, which makes automatic adjustments to audio levels. (See “Audio Level Controls,” later in this chapter.)

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