camera & lens fynction by Topu.pdf

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Tanvir Murad Topu 1

Camera & Lens Function

1.  Types of camera

2.  Shutter

3.  Aperture

4.  Standard or Normal lens; Telephoto lens, Wide angle lens; Zoom lens.

Class Objectives

Camera How an image is formed

Optical Process

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Arabian scholar Ibn al Haitam, in the 10th century, described what can be called a camera obscura

The Human Camera

Eye

Large Format

Medium Format

Small format

Camera Types by Film size & Image Format

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Film size & Image Format

24 x 36mm

Range Finder Single Lens Reflex (SLR)

Camera Types by viewing system

Twin Lens Reflex (TLR)

Basic Camera Types

Conventional Camera

Depends on chemical, mechanical & optical process.

Digital Camera

It has sensors that converts light in to electrical charges which are then turned in to digital information.

Camera types by Technology

Panoramic Camera

Under Water Camera

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Different Parts of a SLR Hot Shoe

Film Rewind

Film Advance Lever

Shutter Release

Lens Lens Lock

Shutter Speed & Film speed Dial

Different Parts of a SLR

SLR- Single Lens Reflex

Professional Digital SLR

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All modern SLRs share some basic features: • A body

• A lens which is interchangeable.

• An adjustable aperture which is inside the lens.

• An adjustable shutter which is inside the body

• A built in TTL light meter Different Parts of a Digital SLR

Shutter Button

Lens Release Button Mode Dial

Hot Shoe

LCD Panel

Different Parts of a Digital SLR (Rear View)

Quick Control Dial LCD monitor

Viewfinder

Menu Button

Play Button

Erase Button

Lens

1550 Girolama Cardano recommends use of bi-convex lens in camera obscura to brighten image.

Lens is a cylinder of shaped pieces of glass (or plastic) that bend rays of light from the subject to create a sharp image on image plane (film/ sensor).

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Different Parts of a Lens

Focusing Ring

Aperture Ring

Focusing

Focusing is the process of moving the lens forward and backward until it produces the sharpest possible image of your main subject, or of the most important part of the scene, on the film in your camera.

Split- Image Focusing

Superimposed- Image Focusing

Ground-Glass Focusing

Automatic Focusing

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Focal Length

A lens’s focal length determines two things- 1.  The first is how big your main subject will be in a photograph, a

variable called magnification. 2.  The second is how much of a scene you can fit in a frame , a

variable called angle of view.

Focal length is the distance between the lens and its image (on the film) when the lens is focused at infinity. Focal length is expressed in millimeters, abbreviated mm.

7.5 mm

50 mm

135 mm

500 mm

28 mm

105 mm

300 mm

1000 mm

Angle of View & Magnification

50mm - Normal (or Standard) Lens for 35mm Cameras

When focused on a subject (s) “normal Lens” collects light rays from an angle of view about 50°- viewing things with about the same perspective as the human eye (when staring straight ahead with one eye closed).

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AC2 = AB2 + BC2 AC2 = (24) 2 + (36) 2

= 576 + 1296 = 1872 AC = 43.26 mm

AC2 = (6) 2 + (6) 2

= 36 + 36 = 72 AC =8.48 cm = 84.8 mm

A

B C

24mm

36 mm

135 Format

43.26 mm

When the Focal length of a lens Equals the diagonal measurement of the film the lens is considered normal.

The Normal Lens

What constitutes Normal depends on the film size.

A

B C

6 cm

6 cm

120 Format

8.48cm

A normal lens is the best choice when you want your lens to create an image in which the scene’s size relationships seem most natural.

Single- Focal- Length Lenses (Fixed-Focal-Length Lenses or

Prime Lens)

Zoom Lens (Variable Focal Lengths)

The Long Lens or The Telephoto Lens [Ex- 70mm, 85mm, 105mm, 300mm, 1000mm etc.]

Lenses with focal lengths much beyond 50mm (for 35mm cameras) are called both long lenses and telephoto lens. A telephoto lens magnifies the subject. This means they make the subject bigger (on the film and in the viewfinder) than it appears in life, without your having to move closer to it physically.

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Telephoto lenses ( example- 105mm or 135 mm) are popular for both candid photography (spontaneous people pictures) and street photography, because they

allow you to position yourself at a distance from the subject, so you can work more discreetly.

Telephoto lens is useful when you want to photograph something in the distance and you can’t or don’t want to get closer to the subject.

Nick Brandt

Also the effect of using the lens is to compress the picture space, making near and far elements seem physically closer together.

Steve McCurry Railway, Agra, 1983

The Wide Angle Lens [Ex- 14mm, 20 mm, 24mm, 28mm, 35mm ]

A wide angle focal length does just what it sounds like it does: it takes in a larger section of the scene you are photographing than you would get with a normal focal length. A wide angle makes subject look smaller than they would be rendered by a normal focal length. The most obvious time to use a wide angle lens is when you otherwise wouldn’t be able to get far enough away from a subject to include it all.

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Wide angle lens are valuable for setting up relationships between foreground and background (near and far) elements. Landscape photographers are specially fond of this tactic, composing with prominent foreground elements (rocks, plants, structures & so on) and also showing a wide expanse of background (mountains, sky and so on).

Photo

Saiful H

uq

A wide- angle focal length lets you get closer to the subject and it gives generous depth of field. So they are very popular among photojournalists.

Tele Zoom (Ex- 100-300mm)

Wide Angle Zoom (Ex- 12- 24 mm)

Wide angle- Tele zoom (Ex- 24-135 mm)

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Aperture

f-2.8

f-4

f-5.6

f-8

f-11

f-16

f-22

Moving to the next f/stop

number either halves or

doubles the amount of light.

Smaller f/stop numbers are larger lens openings and permits more light to pass to the film.

Larger f/stop numbers are smaller lens openings and reduce light passed to the film.

Depth Of Field

The distance range within which objects appear in acceptably sharp focus is commonly called the depth of field.

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Depth of Field

The distance range within which objects appear in

acceptably sharp focus is commonly called the depth of

field.

The wider the lens aperture, the shallower the depth of field.

Photo from Wikipedia

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Photo from Wikipedia Photo: Moinuddin

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Depth of Field & Aperture Size

Depth of Field & Camera Distance

Closer the subject narrower the DOF

Depth of Field & Changing lenses Shortest lens results in the greatest

DOF

Barbara Morgan

Shutter

The shutter speed determines how long the film or sensor is exposed to light.

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Moving the shutter speed dial to the next stop either halves or

doubles exposure time.

Shutter Speed

Shutter

B, 8,4, 2 ,1, 2,4,8,15,30,60,125,250,500,1000,2000...

B= Bulb 8= 8 seconds 1= 1 second 250= 1/250 second

Catching a Moment or Time Exposure [Shutter Priority]

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1/15 1/60 1/250 1/1000

Controlling Motion With Shutter Speed


1/8 1/30 1/125

1/30 1/125 1/500

The direction in which a moving subject is traveling affects how high a shutter speed you’ll need.


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Photo from Wikipedia Photo from Wikipedia

1.  Types of camera- Small, medium & large format camera - View camera, TLR, Rangefinder & SLR.

2.  Moving the shutter speed dial or the f-number to the next stop either halves or doubles exposure.

3.  Use of Shutter: Exposure control, Catching a Moment or Time Exposure

4.  Use of Aperture: Exposure control, Depth of field & Brightness control

5.  Standard or Normal lens; Telephoto lens, Wide angle lens; Zoom lens.

Summary

camera & lens fynction by Topu.pdf

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