Chapter 4 Flashcards
A disc of transparent glass generally bounded by two spherical surfaces capable of transforming an image.
Lens
eye of the camera is also the heart of the camera.
Lens
A piece of transparent material made of glass or plastic with 2 opposite symmetrical surfaces or at least one curved surface.
Lens
A lens that is thicker at the middle than at the edge.
It gathers light rays and refracts them to meet in a certain point.
Convex lens (converging lens/ positive lens)
It is thicker at the edges than at the center;
Light rays passing through a diverging lens are vent outward.
Concave Lens (diverging/negative lens)
composed of 1 lens
Simple Lenses
It consists of two or more simple lenses fitted together.
Compound lenses
It is the largest opening of the diaphragm that the light can pass through.
It is important in taking pictures in dim light
Lens speed
This refers to the size of the image produced by lens depend upon factors – camera – to – subject and focal length
Image size
The distance between the lens (technically from its rear nodal point) and the focal plane when the lens is focused on infinity.
Focal length
The size of the image formed by the lens.
Magnification
The amount of the scene shown on a given size of film.
Angle of view
A lens with a focal length equal to the diagonal measure of the image area.
Standard or normal lens
It has a shorter focal length than the normal lens.
it covers a picture angle of 60 to 90 degrees. It enables photographing a widely extended scene from a close proximity or within a confined area.
Short – focal – lens or Wide Angle Lens
A lens with extreme wide angle.
Fish eye lens
Lens with longer focal length that constrict the field of view and decrease the depth of field while greatly magnifying the image.
Long or Telephoto Lens or Narrow Angle
A special type of camera lens with variable focal length which can be adjusted continuously by the movement of the variable focus lens.
Zoom Lens
Allows the photographer to get close to the subject without the need of special close – up attachment.
Macro Lens
This refers to the use of a macro lens or a special lens attachment when taking this shot
Close – up Shots
This refers to simple close – up attachment fitting between the lens and the SLR camera body.
Extension Ring
This refers to lens that allows photography of objects that is very tall, without the problem of converging verticals; this occurs when the side of the subjects taper toward the top of the picture.
Shift of perspective control lens
The failure of light rays to focus properly after they pass through a lens or reflect from a mirror.
Aberration
The focusing at different points of light rays passing through different parts of spherical lens.
This aberration occurs because light hitting the outer parts of the lens is bent more sharply and comes to a focus sooner than that passing through the middle.
Spherical aberration
The failure of different colored light rays to focus after passing through a lens.
The focusing of light of different colors at different points resulting in a blurred image.
Chromatic aberration
The inability of the lens to bring horizontal and vertical lines in the subject to the same plane of focus in the image.
Astigmatism
It occurs when light falling obliquely on the lens and passing through different circular zones is brought to a focus at different distances from the film plane.
Coma
The plane of sharpest focus becomes curved, not flat.
It is caused by rays from the outer limits of the subject plane coming to focus nearer to the lens than the axial rays.
Curvature of field
It causes the image of a straight line, at the edges of the field to bow in or out.
Distortion
lens with larger maximum aperture (that is, a smaller f-number)
it delivers more light
intensity to the focal plane, allowing a faster shutter speed.
Fast lens
A smaller maximum aperture (larger maximum f – number)
It delivers less light intensity and requires a slower shutter speed
slow lens
This refers to good lenses that are capable of reproducing circles of confusion much smaller than 1/1000
of an inch.
Depth of Focus
This refers to the lens that is focused on an object at infinity, the distance from the lens to the nearest
object in sharp focus.
Hyperfocal distance
This refers to the distance from the optical center of the lens to the focal plane, when the lens is focused on
infinity.
Focal plane
Refers to the distance so far away that rays are considered parallel when they reach the camera.
Infinity
This refers to the point of convergence of the light rays.
Real focus
This refers to the point where diverging rays would meet if their directions were reversed.
Virtual focus
A result of double reflection from inner lens surfaces.
It exhibits self as a misty hazy or cloudy semi circular path of light.
Flare or optical flare
Bright spot on the film caused by stray light from worn shiny parts of the lens such as the stops, shutter, lens mount or from inside the camera itself.
Mechanical flare
Most corrected lenses is coated with a substance which will reduce one type of flare (optical) and which will also increase the optic’s ability to transmit light, thus reducing light to loss.
Light loss
can be reduced or eliminated by using the proper lens, shade places on the front of the lens or shield.
Stray light
