Steadicam

A Steadicam is a stabilizing mount for a motion picture camera, which mechanically isolates the operator's movement from the camera, allowing a very smooth shot even when the operator is moving quickly over an uneven surface. Informally, the word may also be used to refer to the combination of the mount and camera.
Before the steadicam, a director had two choices for moving (or "tracking") shots.
The camera can be mounted on a "dolly", a wheeled mount that rolls on tracks or leveled boards. However, this is time consuming to set up and impractical in many situations. The camera operator can hold the camera in his hands. This allows greater speed and flexibility, but even the most skilled camera operator cannot prevent the image from shaking, if only minutely. Hand-held footage has therefore traditionally been considered suitable mostly for documentaries, news, reportage work, live action, unrehearsable footage, or as a special effect to evoke an atmosphere of authentic immediacy or "cinéma vérité" during dramatic sequences. A steadicam essentially combines the stabilised steady footage of a conventional tripod mount with the fluid motion of a dolly shot and the flexibility of hand-held camera work. While smoothly following the operator's broad movements, the steadicam's armature absorbs any jerks, bumps, and shakes.
The steadicam was introduced to the industry in 1976 by inventor and cameraman Garrett Brown,who originally named the invention the "Brown Stabilizer". After completing the first working prototype, Brown shot a 10-minute demo reel of the revolutionary moves this new device could produce. This reel was seen by numerous directors, including Stanley Kubrick and John Avildsen. The Steadicam was first used in the biopic Bound for Glory, but its breakthrough movies are considered to be Avildsen's Rocky in 1976, and Kubrick's 1980 film The Shining.

Tracking shot

In motion picture terminology, a tracking shot (also known as a dolly shot or trucking shot) is a segment in which the camera is mounted on a wheeled platform that is pushed on rails while the picture is being taken. One may dolly in on a stationary subject for emphasis, or dolly out, or dolly beside a moving subject (an action known as "dollying with").
The Italian feature film Cabiria (1914), directed by Giovanni Pastrone, was the first popular film to use dolly shots, which in fact were originally called "Cabiria movements" by contemporary filmmakers influenced by the film; however, some smaller American and English films prior to 1914 had used the technique prior to Cabiria.
The tracking shot can include smooth movements forward, backward, along the side of the subject, or on a curve. Dollies with hydraulic arms can also smoothly "boom" or "jib" the camera several feet on a vertical axis. Tracking shots, however, cannot include complex pivoting movements, aerial shots or crane shots.
Tracking shots are often confused with the long take such as the 10-minute takes in Alfred Hitchcock's Rope (1948)

Crane shot

In motion picture terminology, a crane shot is a shot taken by a camera on a crane. The most obvious uses are to view the actors from above or to move up and away from them, a common way of ending a movie. Some filmmakers like to have the camera on a boom arm just to make it easier to move around between ordinary set-ups. Most cranes accommodate both the camera and an operator, but some can be operated by remote control. They are usually, but not always, found in what are supposed to be emotional or suspensful scenes. One example of this technique is the shots taken by remote cranes in the car-chase sequence of To Live and Die in L.A..

Focus puller

In cinematography, a focus puller or first assistant camera (1st AC) is a member of a film crew's camera department who is responsible for keeping the camera properly focused during a shoot.
Sharp focus is elemental to reproducing a realistic, appealing image, and a viewer's attention is automatically drawn to sharper areas. When done right, good pulling goes mostly unnoticed by the audience, but soft focus is distracting, nearly impossible to repair after the fact, and can ruin a take. Focus pullers are therefore expected to perform flawlessly every time.
To prepare for a take, the focus puller first measures the distances during rehearsals, sets reference marks with the help of the 2nd AC, compares them with the distance markers on the particular lens being used, and marks them on his/her follow focus ring. During a take, he/she modifies the focus based on the dialog, action, the DP's directions, and compensates on the fly for actors missing their marks or any unforeseen movement. In some situations, an actor's head moving even a few millimeters may require instantaneous focus correction.
Traditionally, the focus puller does not look at the recorded image to do his/her job; using the marks instead of just looking through the viewfinder produces far more reliable and repeatable results. With his/her position beside the camera he/she can see his off-frame marks, and also gain a three-dimensional view of the scene, critical for judging distances. This method evolved with film cameras, which have only one sharp viewing apparatus - taken by the camera operator. With the advent of digital video cameras and increasingly reliable LCD monitors, focus pullers do sometimes check their work on the screen.
Besides his/her eyes, the puller's main tools are a follow focus device and a distance measuring tool - usually with a tape measure or, more recently, with electronic tape measures using lasers (some discourage the use of lasers due to a potential liability resulting from damage that the light might inflict on an actor.
Professional 1st ACs have many tricks for pulling focus in difficult situations or when accurate measurement is impossible. Often, before a scene is even rehearsed or established, the 1st AC will take surveying measurements of the general environment in order to have a good idea of the distance between reference points, such as patterns on the floor or walls, furniture, and whatever else might be around. These reference measurements can be used to quickly establish rough distances between the camera and the subject in chaotic shooting circumstances when it is impossible to accurately measure the distance.

Defocus

In optics, defocus is the one aberration familiar to nearly everyone who has ever needed eyeglasses or used a camera, videocamera, microscope, telescope, or binoculars, as it simply means out of focus. Optically, defocus refers to a translation along the optical axis away from the plane or surface of best focus. In general, defocus reduces the sharpness and contrast of the image. What should be sharp, high-contrast edges in a scene become gradual transitions. Fine detail in the scene is blurred or even becomes invisible. Nearly all image-forming optical devices incorporate some form of focus adjustment to minimize defocus and maximize image quality.

The degree of image blurring for a given amount of focus shift depends inversely on the lens f-number. Low f-numbers, such as f/1.4 to f/2.8, are very sensitive to defocus and have very shallow depths of focus. High f-numbers, in the f/16 to f/32 range, are highly tolerant of defocus, and consequently have large depths of focus. The limiting case in f-number is the pinhole camera, operating at perhaps f/100 to f/1000, in which case all objects are in focus almost regardless of their distance from the pinhole aperture. The penalty for achieving this extreme depth of focus is very dim illumination at the imaging film or sensor, limited resolution due to diffraction, and very long exposure time, which introduces the potential for image degradation due to motion blur.

The amount of allowable defocus may be tied to the resolution of the imaging media. High-resolution black-and-white (B&W) films can resolve image details down to 3 micrometers or smaller, with usable contrast at 150 cycles/millimeter or higher. Modern digital imaging chips and color print films are not as sharp as high-resolution B&W films, but have resolution comparable to each other, and are slightly more tolerant of defocus. If an imaging chip has 10 micrometer pixels, one cycle is therefore two pixels, equal to 20 micrometers or 0.020 millimeters, and the spatial cutoff frequency (limit of resolution) is thus 50 cycles/millimeter at focus.

Defocus is modeled in Zernike polynomial format as a(2ρ2 − 1), where a is the defocus coefficient in wavelengths of light. This corresponds to the parabola-shaped optical path difference between two spherical wavefronts that are tangent at their vertices and have different radii of curvature.