3D   Images that appear to have three dimensions: height, width, and depth.

3DTV   Televisions that are designed specifically for showing 3D programming. Viewers must watch the images through high-precision 3D glasses, which open and close the left and right shutters in synchronization with the alternating images.

3G/4G   A video transmission system that utilizes multiple cellular lines in order to obtain a high-quality transmission.

4K   Also known as “Ultra High Definition,” “Ultra HD,” or “SHV-1.” 4K is defined as at least 3840 horizontal and at 2160 vertical pixels, with an aspect ratio of at least 16 × 9.

8K   Also known as “Super Hi-Vision” and SHV-2. 8K is 16 times more detailed than HD, with 33 million pixels. The 8K system also has 22.2 surround sound.

720p   This HDTV format has 720 scan lines and uses progressive scanning. The 720p format is best for fast-moving motion scenes.

1080i   This HDTV format has 1080 scan lines and uses an interlaced scanning system. The 1080i format has a sharper image than the 720p format.

1080p   This HDTV format has 1080 scan lines and uses a progressive scanning system. It is often referred to as full HD.

Acoustics   Higher-frequency sound waves travel in straight paths and are easily deflected and reflected by hard surfaces. They are also easily absorbed by porous fibrous materials. Lower-frequency sound waves (below 100 Hz) spread widely, so they are not impeded by obstacles and are less readily absorbed. As sound waves meet nearby materials, they are selectively absorbed and reflected; the reflected sound’s quality is modified according to the surfaces’ nature, structures, and shapes. The acoustic characteristics of scenery, furniture, drapes, and people further modify audio quality.

Action line (line/eye line)   The imaginary line along the direction of the action in the scene. Cameras should only shoot from one side of this line.

AD   Associate director (sometimes used for assistant director).

AGC   See Automatic Gain Control.

Ambience   Production ambience influences the audience’s perception of the show. Ambience factors may include music, graphics, and the set.

Analog recording (analogue)   Analog systems directly record the variations of the video and audio signals. They have a tendency to deteriorate when dubbing copies and can only be recorded on tape.

AP   Associate producer.

Aperture   The opening in the lens that lets light into the camera.

Arc shot   A camera move that moves around the subject in a circle, arc, or “horseshoe” path.

ASCAP   American Society of Composers, Authors and Publishers.

Aspect ratio   Aspect radio can be defined as the proportion of width to height of the screen. Televisions have an aspect ratio of 4:3 or 16:9. It is important to keep the aspect ratio in mind when designing sets so that they fit the screen.

Audio filters   May be used to reduce background noises (traffic, air conditioners, wind), or compensate for boomy surroundings.

Audio mixer   A unit used to select, control, and intermix audio sources. It may include filter circuits, reverberation control, and so on. It is usually operated by the audio mixer (a job title as well as the name of the board) or A-1.

Auto-focus   Some lenses are designed to automatically focus on the subject.

Automatic Gain Control   Circuitry in some cameras that automatically adjusts the audio level (higher or lower) to a preset average level.

Backlight control   When there is more light in the background than on the subject, some cameras use a backlight control button, which opens up the iris an arbitrary stop or so above the auto-iris setting to improve the subject’s exposure.

Barn doors   These metal flaps are usually attached to the top, bottom, and sides of the light in order to shape the beam.

Base light   An even lighting covering the area to be shot. This simple light level is enough to create a good video image in the camera. However, it does not create a mood, artistic feel, and so on.

Batten   The horizontal ceiling bar that lights are hung onto in a studio. This bar may include electrical receptacles.

BCU   Big close-up (also known as an extreme close-up).

Bidirectional microphone   This microphone can pick up sounds equally well both in front and in back but is deaf on either side.

Black-stretch control   Some cameras include a black-stretch control button that can be adjusted to make shadow detail clearer and improve tonal gradation in darker tones.

BMI   Broadcast Music Inc.

Bonded cellular   The merging of multiple cellular channels to increase the quality of the transmitted video.

Boom pole   A pole that is used to hold a microphone close to a subject.

Breakdown sheet   An analysis of the script to determine the optimal sequence for shooting the scenes or for analyzing the budget.

Bug   A small logo or score/clock/time period graphic.

Camcorder   A camera with a built-in recording device.

Camera control unit   Equipment that controls the camera from a remote position. The CCU includes setting up and adjusting the camera, luminance, color correction, aperture, and so on.

Camera script   Adds full details of the production treatment to the left side of the “rehearsal script” and usually also includes the shot numbers, cameras used, positions of camera, basic shot details, camera moves, and switcher instructions (if used).

CCD   See charged-coupled device.

CCU   See Camera control unit.

CF   Compact flash.

CG   See character generator.

Character generator   A generic name for any type of television graphic creation equipment.

Charged-coupled device   This device is an image sensor used in most video cameras.

Chroma   Color.

Chroma-key   Utilizing a production switcher, the director can replace a specific color (usually blue or green) with another image source (still image, live video, prerecorded material, etc.).

Clapboard   The clapboard (also known as a clapper or slate) is shot at the beginning of each take to provide information such as film title, names of director and director of photography, scene, take, date, and time. Primarily used in dramatic productions.

Clip   A video segment.

Close-up shot   Encourages the audience to concentrate on a specific feature. Shows emotion and detail.

CMOS   See complementary metal-oxide semiconductor.

Complementary metal-oxide semiconductor   This image sensor has less power consumption, saving energy for longer shooting times.

Composition   Creating an image that is attractive or that captures and keeps the audience’s attention and effectively communicates the production’s message.

Compressor/expander   Deliberately used to reduce or emphasize the audio dynamic range (i.e. the difference between the quietest and loudest sounds).

Condenser microphone   A high-quality microphone that can be very small and is generally powered by an inboard battery, phantom power, or a power supply.

Context   Making sure that the content of the image allows the viewer to understand the subject better; composing a shot in such a way that it includes a background or foreground that adds additional information or context to the image.

Continuity   The goal of continuity is to make sure there is consistency from one shot to the next in a scene and from scene to scene. This continuity includes the talent, objects, and sets. An example of a continuity error in a production would be when one shot shows the talent’s messy hair combed in one direction and the next shot shows it in perfect condition.

Contrast   The difference between the relative brightness of the lightest and darkest areas in the shot.

Coverage   The term used by filmmakers that refers to repeating a scene from enough different angles to ensure that a seamless performance can be maintained throughout multiple takes.

Cover shot   A video clip that is used to cover an edit so that the viewers do not know that the edit occurred.

Crab   See truck.

Crawl   The movement of text horizontally across the television screen.

Credit roll   Continuous information moving vertically into the frame and passing out at the top.

Credits   The text that recognizes those appearing in and contributing to the program.

CU   See close-up shot.

Cue card   The talent may read questions or specific points from a cue card that is positioned near the camera. Generally it is held next to the camera lens.

Cut   The “cut” or “take” is the most common transition when editing. It is an instantaneous switch from one shot to the next.

Cutaway shot   These shots are used to cover edits when any sequence is shortened or lengthened. Generally it is a shot of something outside of the current frame.

Cyclorama (cyc)   A general-purpose detail-less background. It can be neutral, colored with lights, or absent any light (black).

Dead surroundings   When area surfaces are very sound absorbent, the direct sound waves strike walls, the floor, the ceiling, and furnishings and are largely lost. The microphone may pick up only a few weak reflections.

Deep focus   Deep focus, or large depth of field, is when everything in the shot is clearly in focus.

Depth of field   The distance between the nearest and farthest objects in focus.

Diffused light   Soft or overcast light.

Diffusion material   Material that can be attached to the front of a light to reduce the intensity and soften the light beam.

Digital Single Lens Reflex camera   A still camera that shoots video, allowing the photographer to see the image through the lens that will capture the image.

Digital video effect   Equipment, working with the switcher, is used to create special effects between video images. A DVE could also refer to the actual effect.

Digital zoom   Zooming is achieved by progressively reading out a smaller and smaller area of the same digitally constructed image. The image progressively deteriorates as the digital zoom is zoomed in.

Director   The person responsible for telling the story with video.

Directional microphone   This type of microphone can pick up sounds directly in front of it.

Dissolve (mix)   A gradual transition between two images. A dissolve usually signifies a change time or location.

Dolly (track)   (1) The action of moving the whole camera and mount slowly toward or away from the subject. (2) A platform with wheels that is used to smoothly move a camera during a shot.

Drag   The variable friction controls located on a tripod head that steady the camera’s movements.

DSLR   See Digital Single Lens Reflex camera.

DVE   See digital video effect.

Dynamic microphone   A rugged, low-maintenance, not easily distorted microphone.

Dynamic range   The range between the weakest and loudest sounds that can be effectively recorded by a recording device.

ECU   Extreme close-up (sometimes called XCU).

EFP   See electronic field production.

Electronic field production   Generally means shooting in the field with one or more cameras.

Electronic news gathering   Usually refers to shooting with a single camera outside the studio.

Ellipsoidal   The ellipsoidal light is a sharply focused/defined spotlight.

ELS   Extreme/extra long shot.

Empirical production method   The method where instinct and opportunity are the guides.

ENG   See electronic news gathering.

Equalizer   An audio filter that can boost or reduce any segment of the audio spectrum.

EXT   Abbreviation for exterior location that is generally used in scripts.

Eye line (line)   Where people appear to be looking, or line of sight.

Fade   A gradual change (dissolve) between black and a video image. Usually defines the beginning or end of a segment or program.

FCC   Federal Communications Commission.

Filmic time   This editing technique tightens up the pace of a production by leaving out potentially boring portions of the scene when the audience interest could wane.

Filter wheel   Filters may be required to obtain the best color in a video camera. Filters are often fitted inside the video camera, just behind the lens on a filter wheel. Typical correction filters include daylight, artificial/tungsten light, and fluorescent light (perhaps marked 6000 K, 4700 K, and 3200 K). The filter wheel may also include or combine ND filters to improve exposure.

Fish pole   See microphone boom.

Flash memory   These cards can store large amounts of digital data without having any moving parts. This makes them durable, able to work in a variety of temperatures, and data can be easily transferred into a nonlinear editor.

Flood lighting   The light scatters in all directions, providing a broad, nondirectional light.

FM   Floor manager (also known as stage manager).

Focal length   Simply an optical measurement—the distance between the optical center of the lens and the image sensor, when you are focused at a great distance such as infinity. It is measured in millimeters (mm) or inches.

Focus zone   See depth of field.

Foley   Creating sound effects that can be used to replace the original sounds such as hoofbeats, footsteps, and so on.

Follow focus   This technique requires the camera operator to continually change the focus as the camera follows the action.

Format   The show format lists the items or program segments in a show in the order they are to be shot. The format generally shows the durations of each segment and possibly the camera assignments.

Freelance   Independent contractors who provide services to multiple organizations, hiring out their skills on an as-needed basis.

Fresnel   The Fresnel is generally an unfocused spotlight (some can be focused). It is lightweight, less expensive than an ellipsoidal, and it has an adjustable beam.

FS   Full shot.

f-stop   The f-stop regulates how much light is allowed to pass through the camera lens by varying the size of the hole the light comes through.

Full script   A fully scripted program includes detailed information on all aspects of the production. This includes the precise words that the talent/actors are to use in the production.

Gaffer   The head of the electrical department, many times in charge of lighting on a television set.

Gain   (1) (video) Amplification of the camera video signal, usually resulting in some video noise. (2) (audio) Amplification of the audio signal.

Gel   Colored flexible plastic filters used to adjust the color of the lights.

Goals   Broad concepts of what you want to accomplish with the program.

Graphic equalizer (shaping filter)   Graphic equalizers have a series of slider controls, allowing selected parts of the audio spectrum to be boosted or reduced.

Grip clamps   These clamps are designed so that a light can easily be attached. The clamp is then used to attach the light to almost anything.

Group shot   A term used by a director when instructing a camera operator to shoot a shot of the whole group.

GS   See group shot.

Handheld camera   A camera that is held by a person and not supported by any type of camera mount.

Handheld microphone   The handheld mic is widely used by news reporters and musicians.

Hard disk drive   Can be used for recording digital video images and can be built into the camera or attached to the outside of the camera.

HD   High definition.

HDD   See hard disk drive.

HDSLR   A high-definition (HD) version of a DSLR. (See DSLR description above.)

HDTV   See high-definition television.

Headroom   The space from the top of the head to the upper frame.

High angle   When the camera is positioned higher than the subject.

High-definition television   The standard high-definition formats currently in use range from 720 to 1080 lines of resolution.

Hue   Refers to the predominant color—for example, blue, green, and yellow.

I-mag   An abbreviation for “image magnification.” Refers to large video screen production at events.

INT   Abbreviation for interior location used on scripts.

Intellectual property   Property (music, video, etc.) whose owners have been granted certain legal exclusive rights.

Interactive television   Refers to online programming that allows the viewer to make choices about how they watch an event.

Intercom   A wired or wireless communication link between members of the production crew.

Interlaced scanning   The television’s electron scans the odd-numbered lines first and then goes back and “paints” in the remaining even-numbered lines.

Internet Protocol Television   Utilizes the Internet to provide programming to its audience instead of broadcast or cable television.

IP   See intellectual property.

IPTV   See Internet Protocol Television.

Iris   The diaphragm of the lens that is adjustable. This diaphragm is adjusted open or closed, based on the amount of light needed to capture a quality image.

ISO   While all the cameras are connected to the switcher as before, the ISO (or isolated) camera is also continuously recorded on a separate recorder.

iTV   See interactive television

Jib   A counterbalanced arm that fits onto a tripod that allows the camera to move up, down, and around.

Jump cut   A jump cut is created when the editor cuts between two similar shots (two close-ups) of the same subject.

Lavaliere microphone   These small microphones clip on the clothing of the talent and provide fairly consistent, hands-free, audio pickup of the talent’s voice.

LCD   See liquid crystal display.

LED light panel   A camera or studio light that is made from a series of small LED bulbs.

LFE   Low-frequency effects.

Limiter   A device for preventing loud audio from exceeding the system’s upper limit (causing overload distortion), by progressively reducing circuit amplification for louder sounds.

Linear editing   The copying, or dubbing, segments from the master tape to another tape in sequential order.

Liquid crystal display   These flat-screen displays work by sending variable electrical currents through a liquid crystal solution that crystallizes to form a quality image.

Live surroundings   When an area contains predominantly hard surfaces, the sound is strongly reflected. This results in more echo.

Location   A place used for shooting outside of the studio.

Logging   Loggers view the footage and write down the scene/take numbers, the length of each shot, time code, and descriptions of each shot.

Long shot or wide-angle shot   Helps establish the scene for the viewer.

Low angle   When the camera is positioned lower than the subject.

Lower third (L/3rd)   A graphic that appears in the lower third of screen. Traditionally it contains biographical information.

LS   Long shot (also known as full shot).

Luminance   The brightness of the image, how dark or light it appears.

Macro   Some lenses include a macro setting, a lens capable of extreme close-ups.

Medium shot   The medium shot tells the story; it is close enough to show the emotion of the scene but far enough away to show some of the relevant context of the event.

MFD   See minimum focused distance.

Microphone (mic) boom   A pole that is used to hold a microphone in order to get the mic close to the action.

Minimum focused distance   The closest distance a lens can get to the subject. With some telephoto lenses, the MFD may be a few yards. Other lenses may be ¼ of an inch.

Monaural (mono)   One audio track.

Monitors   Monitors were designed to provide accurate, stable image quality. They do not include tuners and may not include audio speakers.

Monopod   A camera support with one leg.

MS   Medium shot.

Multicamera production   Occurs when two or more cameras are used to create a television production. Usually the cameras are switched by a production switcher.

Narrow-angle lens   See telephoto lens.

NAT   See natural sound.

Natural sound   The recording of ambient or environmental sounds on-location.

ND   See neutral-density filter.

Neutral-density filter   A filter that reduces the amount of light coming into the camera without changing the color of the image.

Nonlinear   The process where the recorded video is digitized (copied) onto a computer. Then the footage can be arranged and rearranged, special effects can be added, and the audio and graphics can be adjusted using editing software.

Normal lens   The type of lens that portrays the scene approximately the same way a human eye might see it.

OB   See outside broadcast.

Objective camera   The objective camera role is that of an onlooker, watching the action from the best possible position at each moment.

Objectives   Measurable goals. That means something that can be tested for to see that the audience did understand and remember the key points of the program.

Omnidirectional microphone   This type of microphone can pick up audio equally well in all directions.

Open set   Created by carefully grouping a few pieces of furniture in front of the wall. Even as little as a couch, a low table, a table lamp, potted plants, a screen, chair, and a stand lamp can suggest a complete room.

Optical zoom   The optical zoom uses a lens to maintain a high-quality image throughout its zoom range.

Outline script   This script usually provides the prepared dialog for the opening and closing and then lists the order of topics that should be covered. The talent will use the list as he or she improvises throughout the production.

Outside broadcast   Also known as a remote production, an OB takes place outside of the studio.

PA   Production assistant.

Pan head   The pan head, or tripod head, enables the camera to tilt and pan smoothly. Variable friction controls (drag) steady these movements. The head can also be locked off in a fixed position. Tilt balance adjustments position the camera horizontally to assist in balancing the camera on the mount.

Pan shot   When the camera pivots on its mount to the left or right.

Patch panel/jackfield   Rows of sockets to which the inputs and outputs of a variety of audio units are permanently wired. Units may be interconnected with a series of plugged cables (patch cords).

Pedestal   (1) An adjustable camera support that has wheels. These are normally used in a studio. (2) Can refer to the black level of a video image shown on a waveform monitor. (3) Also can refer to the action of raising a camera higher.

Per diem   Refers to a set amount of money paid per day, above the normal pay, to a worker to cover living expenses when traveling.

Photographic lighting   See three-point lighting.

Pickup shot   If an error is made during the shooting of a scene, a pickup shot is used by changing the camera angle (or shot size) and retaking the action from just before the error was made.

Planned production method   The planned method, which organizes and builds a program in carefully arranged steps.

Point of view shot   Generally shows a person’s point of view or is a miniature camera that is positioned to show a unique angle of the subject.

Postproduction   Editing, additional treatment, and duplication of the project.

POV   See point-of-view shot.

Preamplifier   An amplifier used to adjust the strength of audio from one or more audio sources to a standard level (intensity). It may include source switching and basic filtering.

Prime lens   A prime lens (primary lens) has a fixed coverage, field of view, or focal length.

Progressive scanning   This sequential scanning system uses an electron beam that scans or paints all lines successively, displaying the total picture.

Prop   Props, or property, are handled on the set by the talent during a production.

PRS   Performing Rights Society.

Pull focus   A person who assists the camera operator by focusing the camera’s lens.

Quick-release mount   This mount is attached to the camera and fits into a corresponding recessed plate attached to the tripod/pan head. This allows the camera operator to quickly remove or attach the camera to the camera mount.

RAW   Uncompressed data from the sensor of a digital camera.

Reaction shot   A shot of a person’s face that is registering a response to something in the program.

Rehearsal script   This script usually includes the cast/character list, production team details, rehearsal arrangements, and so on. There is generally a synopsis of the plot or story line, location, time of day, stage/location instructions, the action, dialog, effects cues, and audio instructions.

Remote survey (Recce)   A preliminary visit to a shooting location.

Remote truck (OB van)   A mobile television control room that is taken away from the studio.

Reverberation   A device for increasing or adjusting the amount of echo accompanying a sound.

RF   Radio frequency.

Roll   The movement of text up or down the video screen.

Running order   The order that the scenes or shots will be shown in the final project, which may differ greatly from the shooting order.

Safe title area   The center 80 percent of the screen where it is safe to place graphics.

Sampling rate   Measures how often the values of the analog video signal are converted into a digital code.

Saturation   The chroma, purity, and intensity. It affects a color’s richness or paleness.

Scene   Each scene covers a complete continuous action sequence.

Scoop   A simple floodlight. It is inexpensive, usually not adjustable, lightweight, and does not have a sharp outline.

SDI   Serial digital interface.

Second screen   Today’s television audience is not just watching television; they are also on a computer of some type, often called the “second screen.”

SESAC   Society of European State Authors and Composers.

Shooting order   The order that the scenes or shots may be recorded using the video camera, which may differ greatly from the running order.

Shotgun microphone   A highly directional microphone used to pick up sound from a distance.

Shot sheet (shot card)   This sheet, created by the director, is a list of each shot needed from each individual camera operator. The shots are listed in order so that the camera operator can move from shot to shot with little guidance from the director.

Show format   The detailed order of the scripted production.

SHV   Super Hi-Vision.

Single-camera production   Occurs when one camera is used to shoot the entire segment or show.

Site survey   A meeting of the key production personnel at the proposed shooting location. A survey allows them to make sure that the location will meet their production needs.

SMPTE   See Society of Motion Picture and Television Engineers.

Society of Motion Picture and Television Engineers   This international professional organization has developed over 400 standards, practices, and engineering guidelines for audio, television, and the film industry.

Softlight   Provides a large level of diffused light.

Spotlight   A highly directional light.

Spreader   A base for a tripod that stabilizes the legs and prevents them from spreading.

Stand-by   To alert the talent to prepare for a cue.

Stereo   Stereo sound uses two audio tracks to create an illusion of space and dimension.

Stick mic   See handheld microphone.

Storyboard   The storyboard is simply a series of rough sketches that help you to visualize and to organize your camera treatment.

Streaming   Programming that is shown live or transmitted from a video-sharing site to a computer.

Stretch   Tell the talent to go more slowly (there is time to spare).

Subjective camera (point of view/POV)   The camera represents the talent’s point of view, allowing the audience to see through the talent’s eyes as the camera moves through a crowd or pushes aside undergrowth.

Subtitles   Identify people and places.

Surround sound   Surround uses six audio tracks to create a sense of enve lopment.

Switcher (vision mixer)   A device used to switch between video inputs (cameras, graphics, video players, etc.).

Take   See cut.

Talent (performer)   Anyone who appears in front of the camera.

TD   Technical director.

Telephoto lens   A narrow-angle lens that is used to give a magnified view of the scene, making it appear closer. The lens magnifies the scene.

Teleprompter   A device that projects computer-generated text on a piece of reflective glass over the lens of the camera. It is designed to allow talent to read a script while looking directly at the camera.

Television receivers   Television sets include a tuner so that they can display broadcast programs with their accompanying sound.

Three-point lighting   A lighting technique that utilizes three lights (key, fill, and back lights) to illuminate the subject.

Tighten shot   Zoom in.

Tilt balance   Adjustments located on the pan head of a tripod that position the camera horizontally to assist in balancing it on the mount.

Tilt shot   Occurs when the camera moves up or down, pivoting on a camera mount.

Time code   A continuous time-signal throughout the tape, showing the precise moment of recording.

Timeline   Usually includes multiple tracks of video, audio, and graphics in a nonlinear editing system.

Treatment   An overview of the video script that usually includes an explanation of the characters and story plot.

Triangle lighting   See three-point lighting.

Trim   To cut frames off a shot to make it shorter.

Tripod   A camera mount that is a three-legged stand with independently extendable legs.

Tripod arms (pan bars)   Handles that attach to the pan head on a tripod or other camera mount to accurately pan, tilt, and control the camera.

Truck (crab)   The truck, trucking, or tracking shot is when the camera and mount move sideways (left or right) with the subject.

Underexpose   Occurs when the lens lets an insufficient amount of light into the camera. The result is a darker image with a loss of detail.

Video-sharing sites   Online sites that enable producers to upload programming so that it can be seen by an audience.

Videotape   Tape has been the traditional means of recording video images. However, it is slowly being replaced by hard drives and flash cards.

Viewfinder   Monitors the camera’s picture. This allows the camera operator to focus, zoom, and frame the image.

Virtual set   Uses a blue or green seamless background, chroma-keying the computer-generated set into the scene. Most virtual sets employ sophisticated tracking computer software that monitors the camera’s movements so that as the camera zooms, tilts, pans, or moves in any other way, the background moves in a corresponding way.

Visual storytelling   The use of images to convey a compelling story.

VLS   Very long shot (also known as extreme long shot).

VOD   Video on demand.

Voiceover   Commentary over video.

VU meter   An instrument designed to measure audio levels.

Waveform monitor   An oscilloscope that is designed to monitor a video signal. This ensures that all colors will be correctly recorded.

Whip pan (zip pan)   A quick pan shot that usually results in the subject being blurred.

White balance   The process of calibrating a camera so that the light source will be reproduced accurately as white.

Wide-angle lens   Shows us a greater area of the scene than is normal. The subject looks unusually distant.

Wild-track interviews   Usually means that while images are being shown of a person doing something (sawing wood, for example), the voice of the person shown in the images is heard being interviewed, like a voice-over.

Wipe   A special-effect transition between two images. Usually shows a change of time, location, or subject. The wipe adds novelty to the transition but can easily be overused.

WS   Wide shot.

XLR   A professional audio connector. Usually but not limited to three pins.

Zone focus   Camera operators are focused on a portion of the scene. Any time the subject comes into that area, the camera has been prefocused to make sure the action is sharp.

Zoom lens   A lens that has a variable focal length.