Chapter 4 Lens Flashcards
A disc of transparent glass generally bounded by two spherical surfaces capable of transforming an image.
Lens
A piece of transparent material made of glass or plastic with 2 opposite symmetrical surfaces or at least one curved
surface
Lens
The eye of the camera is also the heart of the camera.
Lens
The eye of the camera is also the heart of the camera.
Lens
B. Typology of Lenses (Pallista, 2019)
General Classification
Simple Lenses
Compound Lenses
composed of 1 lens
Simple Lenses
Simple lenses generally produce aberrated (imperfect) images which can be corrected using compound lenses .
Compound Lenses
It consists of two or more simple lenses fitted together
Compound Lenses
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)
is the largest opening of the diaphragm that the light can pass through.
Lens Speed
is important in taking pictures in dim light
Lens Speed
Types of lenses based on Lens Speed
Fast Lens
Slow Lens
A lens with larger maximum aperture (that is, a smaller f-number) is a fast lens because it delivers more light
intensity to the focal plane, allowing a faster shutter speed.
Fast Lens
A smaller maximum aperture (larger maximum f – number) is slow lens because it delivers less light intensity and
requires a slower shutter speed.
Slow Lens
This refers to the size of the image produced by lens depend upon factors – camera – to – subject and focal
length
Image Size
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 is called
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
This 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
Groups of Lenses According to Focal Length and Characteristics are?
Lens is characterized by its focal length
Short – focal – lens or Wide Angle Lens
Fish Eye Lens
Long or Telephoto Lens or Narrow Angle
Zoom Lens
Macro Lens
Shift of Perspective Control Lens
The distance between the lens (technically from its rear nodal point) and the focal plane when the lens is focused on
infinity.
Focal Length
Focal length controls the following:
Magnification
Angle of view
Standard or Normal Lens
A lens with a focal length equal to the diagonal measure of the image area
Standard or Normal Lens
The amount of the scene shown on a given size of film
Angle of view
The size of the image formed by the lens
Magnification
It has a shorter focal length than the normal lens.
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 close – up shots.
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
Lens Defects are?
Spherical aberration
Chromatic aberration
Astigmatism
Coma
Curvature of Field
Distortion
causes the image of a straight line, at the edges of the field to bow in or out.
Distortion
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 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 inability of the lens to bring horizontal and vertical lines in the subject to the same plane of focus in the image
Astigmatism
The failure of different colored light rays to focus after passing through a lens
Chromatic aberration
The focusing at different points of light rays passing through different parts of spherical lens
Spherical aberration
Other Lens Defects
are?
Flare or Optical Flare
Mechanical Flare
Light Loss
Stray Light
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
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
It can be reduced or eliminated by using the proper lens, shade places on the front of the lens or shield
Stray Light
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
