4

Question 1

disc of transparent glass generally bounded by two spherical surfaces capable of
transforming an image.
2. The eye of the camera is also the heart of the camera

Answer 1

LENS

Question 2

How a Lens Work?

Answer 2

Gather light rays from a subject

Question 3

– composed of 1 lens

Answer 3

Simple Lenses

Question 4

• It consists of two or more simple lenses fitted together.
• Simple lenses generally produce aberrated (imperfect) images which can be
corrected using compound lenses .

Answer 4

Compound Lenses

Question 5

• 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

Answer 5

Convex Lens (converging lens/ positive lens)

Question 6

• It is thicker at the edges than at the center; light rays passing through a
diverging lens are vent outward.

Answer 6

Concave Lens (diverging/negative lens)

Question 7

is the largest opening of the diaphragm that the light can pass
through.
• Lens speed is important in taking pictures in dim light.

Answer 7

Lens Speed

Question 8

Types of lenses based on Lens Speed

Answer 8

Fast lens
Slow lens

Question 9

• A lens with larger maximum aperture (that is, a smaller f-number)
because it delivers more light intensity to the focal plane, allowing a faster
shutter speed.

Answer 9

Fast Lens

Question 10

• A smaller maximum aperture (larger maximum f – number) is slow lens because
it delivers less light intensity and requires a slower shutter speed.

Answer 10

Slow Lens

Question 11

This refers to the size of the image produced by lens depend upon factors –
camera – to – subject and focal length. The lens collects the rays reflection from each point
and brings them into focus at the focal plane.

Answer 11

Image Size –

Question 12

– This refers to good lenses that are capable of reproducing circles of
confusion much smaller than 1/1000 of an inch.

Answer 12

Depth of Focus

Question 13

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

Answer 13

Hyperfocal Distance –

Question 14

– This refers to the distance from the optical center of the lens to the focal
plane, when the lens is focused on infinity

Answer 14

Focal Plane

Question 15

– This refers to the distance so far away that rays are considered parallel when
they reach the camera.

Answer 15

Infinity

Question 16

This refers to the point of convergence of the light rays

Answer 16

Real Focus –

Question 17

– This refers to the point where diverging rays would meet if their
directions were reversed.

Answer 17

Virtual Focus

Question 18

• The distance between the lens (technically from its rear nodal point) and the focal
plane when the lens is focused on infinity.

Answer 18

Focal Length

Question 19

Focal length controls the following:

Answer 19

Magnification
Angle of view
Standard or Normal Lens

Question 20

• A lens with a focal length equal to the diagonal measure of the image area.
• By international standards, 50 mm.

Answer 20

Standard or Normal Lens

Question 21

• The size of the image formed by the lens.

Answer 21

Magnification

Question 22

• The amount of the scene shown on a given size of film.
• Classification of Lens Based on Focal Length

Answer 22

Angle of view

Question 23

• It has a shorter focal length than the normal lens. Hence, 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.

Answer 23

Short – focal – lens or Wide Angle Lens

Question 24

• A lens with extreme wide angle.
• Characteristics of Fish Eye Lens
• It provides a field of view of 180 degrees or more

Answer 24

Fish Eye Lens

Question 25

• 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

Answer 25

Long or Telephoto Lens or Narrow Angle

Question 26

• A special type of camera lens with variable focal length which can be adjusted continuously by the movement of the variable focus lens. • This lens allows quick adjustment to give a wider or narrower field of vision but keeping the image in focus.

Answer 26

5. Zoom Lens

Question 27

refers to a. The failure of light rays to focus properly after they pass through a lens or reflect from a mirror.

Answer 27

Aberration

Question 28

• The focusing at different points of light rays passing through different parts of • 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.

Answer 28

Spherical aberration

Question 29

• 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.

Answer 29

Chromatic aberration

Question 30

• The inability of the lens to bring horizontal and vertical lines in the subject to the same plane of focus in the image. • occurs at the edge of the image; the image appears elliptical or crossshaped because of an irregularity in the curvature of the lens.

Answer 30

Astigmatism

Question 31

• 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. • A spot of light appears to have a tail, rather like a comet.

Answer 31

Coma

Question 32

• 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.

Answer 32

Curvature of Field

Question 33

causes the image of a straight line, at the edges of the field to bow in or out.

Answer 33

Distortion

Question 34

Types of distortion

Answer 34

Pincushion distortion Barrel distortion

Question 35

Other Lens Defects

Answer 35

Flare or Optical Flare Mechanical Flare Light Loss Stray Light

Question 36

• A result of double reflection from inner lens surfaces. • It exhibits self as a misty hazy or cloudy semi circular path of light.

Answer 36

1. Flare or Optical Flare

Question 37

• 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.

Answer 37

2. Mechanical Flare

Question 38

• 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.

Answer 38

3. Light Loss

Question 39

• It can be reduced or eliminated by using the proper lens, shade places on the front of the lens or shield.

Answer 39

Stray Light