The Video Camera

1
The Video Camera

• Basic Inage Formation
• Basic Camera Function and Elements
• Types of Cameras

2
Basic Image Formation

• Key Concept - A television frame is made of two
  scanning fields. There are thirty frames (or
  sixty fields) per second.

3
Television Sets and Cameras Are Similar

• NTSC Standards (National Television System
  Committee)
• Basic Colors Red - Blue - Green
• All odd lines Field 1
• All even lines Field 2
• Field 1 and 2 equal a frame

4
Television Sets and Cameras Are Similar

• 525 lines of resolution
• High Definition has 1,125 lines
• still operating on 30 frames p/second

5
Basic Camera Function

• To convert an optical image into electrical
  signals that are reconverted by a TV receiver
  into visible screen images

6
Basic Camera Elements

• Lens - Projects image onto camera Surface
• Camera - Transforms optical projection into
  electrical energy
• Viewfinder - reconverts to optical for cameral
  operator

7
Lens

• Determines what the camera can see
• Classified by focal length
• Short focal length wide angle view
• Long focal length narrow angle view

8
Zoom Lens is variable focal length

• Zoom out wide angle/short focal length
• Zoom in narrow angle/long focal length
• Mid Zoom normal view/similar to human eyesight

9
Zoom Range

• Refers to range of narrowest to widest shot
• 10 to 1 means the narrow is 10 times magnified
  over the wide
• Larger ratios indicate greater range, cost and
  focal length

10
Lens Speed

• How much light can pass through the lens to the
  imaging device
• Fast lens lots of light
• Slow lens limited light
• Fast lens more useful
• Lowest f/stop number indicates speed of lens

11
Lens Iris and f-stops

• A diaphragm which controls light
• Also called aperture
• Referenced in numbers
• Smaller number larger opening more light

12
Key Concept 2

• The lower the f-stop number, the larger the
  aperture and the more light is transmitted. A
  fast lens has a low minimum f-stop number (such
  as f/1.4)

13
Key Concept 3

• The higher the f-stop number, the smaller the
  aperture and the less light is transmitted. A
  slow lens has a relatively high minimum f-stop
  number (such as f/4.5)

14
Auto Iris

• automatically adjusting to optimum aperture.
  Light level is read by camera and servo motor
  typically sets iris.

15
Beam Splitter

• Separates ordinary light into the 3 primary light
  colors RED - GREEN - BLUE
• Referred by technicians as RGB
• Color camera has an imaging device for each
  primary color

16
Key Concept 4

• The CCD (Charge-coupled device) converts light
  into electrical energy or the video signal

17
Notes on Imaging Devices

• Pro gear will have 3 CCDs p/camera
• Consumer gear usually 1 CCD
• Single chip cameras have convenient size
• Signal processing is the amplification of the
  electrical RGB signals

18
Key Concept 5

• The composite color signal combines and RGB
  chrominance channel with a black and white
  luminance channel

19
Camera Viewfinder

• A monitor showing an image close the the one seen
  by viewers
• Usually monochrome
• Allows operator to develop picture composition
• Can show a switcher mix

20
Types of Cameras

• Studio
• ENG/EFP
• Small format

21
Key Concept 6

• The camera chain consists of the camera head
  (actual camera), a power supply, a sync generator
  and a CCU (camera control unit)

22
Key Concept 7

• A camcorder has its VTR attached or built into
  (docked) the camera.