Cinema Ch 10 Terms

Horizontal dimension

x-axis

Vertical dimension

y-axis

Depth dimension

z-axis. illusion created by the composition of the frame. Wide angle tend to exaggerate depth

1/3-2/3 rule

2/3 of the depth range along the z-axis is behind the focus point and 1/3 is in front.

Focal plane (film plane)

A lens gathers incoming light and focuses it on the film plane. Face plate of the CCD chip

Lens speed

Ability of a lens to gather light.

Zooming in

Adjusting the optical center away from the focal plane and therefore increasing the magnification power of the lens (telephoto)

Zooming out

Adjusting the optical center back toward the focal plane, causing the image to become more wide angle.

Focus point

Aka. plane of critical focus. Precise distance in front of the camera, from the focal plane which will be in sharp focus.

Aperature

All light gathered by the lens must pass through the aperture before it is registered on film plane or imaging device.

Auto focus

Camera setting which favors objects in the center of the frame, and tends to shift focus in the middle of a shot when anything moves across the foreground of the frame.

Fast lens

Can open up to allow more light

Pulling focus

Change the plane of critical focus during a take, when the camera is running. Common practice

Aperature ring

Controls a slender disk, a diaphragm, inside the lens called the iris, which is made up of flat matte black metal blades.

Focal length

Determines the degree of magnification or de-magnification of the scene being shot. Determined by the distance between the optical center of the lens and the focal plane. Usually measured in millimeters

Stop

Each number on the f-stop scale. One stop has the effect of doubling or halving the amount of light allowed to pass.

Opening up

Expanding the aperture (smaller numbers)

T-stops

F-stops that have been adjusted to take into account the amount of light that is lost, dissipated or absorbed by that particular lens. Simply more accurate f-stops

Neutral density

Filters to block light

Presetting focus

First zoom all the way into the subject you want to have in focus, adjust the focus, and now zoom out and find your initial frame

Face plate

Focal plane where light is focused. front of the CCD chip

Focus

Generally defined as when a point of light reflecting off the subject is registered as a point of light on the focal plane.

Barrel

Holds the lens elements parallel to each other in a light-tight housing. Aka. Lens housing

Angle of view

How much of the scene the lens takes in horizontally and vertically

Prime lenses

Lenses that have one fixed focal length. Very common film production. Simple design allows them to be made with few glass lens elements, which means there is less chance for loss of light.

Witness mark

Line etched into a nonmovable part of the lens barrel

Telephoto Lens

Long lenses. Enlarge the size of the image and narrow the angle of view.

Manual mode

Manually adjusting focus.

Normal Lens

Medium lenses. Approximates the same perspective and image size that the human eye would see if one were to stand in the same spot as the camera

Zoom lenses (variable focal length lenses)

Offer a continuos range of focal lengths in one lens housing. Constructed with movable lens elements. Can offer a wide range of focal lengths in one lens

Focus ring

On a lens, brings a subject into focus by very precisely moving the front element of the lens forward and backward in relation to the focal plane

Slow lens

Opens up slower to gather light

Focus puller

Person who does the actual adjustments to the focus ring.

Setting marks

Place precise markers on the ground for the actor to hit during the course of their movement.

Rack focus

Shifting the plane of critical focus between two static objects along the z-axis

Wide angle Lens

Short lenses, and shorter focal lengths. Reduce the size of the image and broaden the angle of view.

Electronic shutter control

Reduce the light entering the camera

Closing down (stopping down)

Reducing the size of the aperture (bigger numbers)

Lens elements

Series of polished glass sections

F-stop scale

Size of the aperture opening calibrated. Etched into the aperture ring

Follow focus

Subject is moving along the z-axis either closer to or further away from the camera

Circle of confusion

The measurement of acceptable diameter, which creates the appearance of focus

Optical center

The point at which the image flips

Depth of field

range of apparent focus along the z-axis.