Lens Flashcards
The eye of the camera is also a heart of the camera
Lens
A piece of transparent material made of glass or plastic with 2 opposite symmetrical surface or at least one curved surface
Lens
General classification of lenses
- Simple lenses
- Compound lenses
It composed of 1 lens
Simple lenses
A lens that is thicker at the middle than at the edge
Convex Lens
It gathers light rays and refracts them to meet in a certain point
Convex Lens
It is thicker at the edges than at the center; light rays passing through a diverging lens are vent outward
Concave Lens
It consists of two or more simple lenses fitted together
Compound lenses
Produce aberrated image which can be corrected using compound lenses
Simple lenses
It Is a combination of lenses
Compound lenses
It is a number of mega fixel
Image size
Image produced by the lens depends upon factors camera- to - subject and focal length
Image size
Small circle or blur are called?
Circle of confusion
Refers to the distance from the optical center of the lens to the focal plane, when the lens is focused on infinity
Focal plane
The distance between the lens and the focal plane when the lens is focused on infinity
Focal length
Focal length controls the following:
a. Magnification
b. Angle of view
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
By international standards, 50 mm
Standard or normal lens
Lenses with focal lengths from 45 to 60 millimeters are normal lenses because they produce an image that is approximately the same with the view angle of the human eye which is 45 degrees
Standard or normal lens
Groups of lenses according to focal length and characteristics
- Standard or Normal lens
- Short- focal - lens or wide angles lens
- Fish eye lens
- Long or Telephoto lens or Narrow angle
- Zoom lens
- Macro lenses
It has a shorter focal length than the normal lens. Hens it covers a picture angle of 60 to 90 degrees.
Short- focal -lens or wide angles lens
A lens with extreme wide angle
Fish Eye Lens
It provides a field of view of 180 degrees or more
Fish eye lens
A6- millimeters fish-eye lens made by Nikon has a ____ degree field of view
220
Provides an enlarged image of an object
Long of telephoto lens or Narrow lens
Lens with longer focal length that constrict the field of view and decrease the depth of field while greatly magnifying the image. e.g. 85mm, 100mm, 200mm, 300mm etc.
Long or telephoto lens or Narrow lens
Allows you to take close – up shots while keeping your distance (reach out like telescope) to provide greatly enlarged of a distant object.
Long or telephoto lens or Narrow lens
Provides shallow dept of field.
Long or telephoto lens or Narrow lens
Angle of view is less than 45 degrees
Long or telephoto lens or Narrow lens
This lens allows quick adjustment to give a wider or narrower field of vision but keeping the image in focus.
e.g. 24mm – 135mm
Zoom lens
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
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.
Spherical aberration
The failure of different colored light rays to focus after passing through a lens.
Chromatic aberration
The focusing of light of different colors at different points resulting in a blurred image.
Chromatic aberration
occurs at the edge of the image; the image appears elliptical or cross-shaped because of an irregularity in the curvature of the lens.
Astigmatism
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
A spot of light appears to have a tail, rather like a comet.
Coma
The plane of sharpest focus becomes curved, not flat
Curvature of field
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
Allows photographer to get close to the subject without need of special closed up attachment
Macro lenses
Lens defects
- Spherical aberration
- Chromatic aberration
- Astigmatism
- Coma
- Curvature of field
- Distortion
Cause the image of straight line at the edge of field to bow in or out
Distortion
Other lens defects
- Flare or Optical Flair
- Mechanical Flair
- Light loss
- Stray light
