Camera

1
Lecture 2

• Camera Video Basics

2
Camera Optics

• Focal length

Optical axis
Thin spherical lens
3

• Focus

4

• Distance vs. Focusing

5

• Focusing Issues
• Auto vs. manual focusing
• Focusing changes image size.
• Motion analysis manual focusing
• Depth of field
• Aim the far object.

6

• Distance vs. Focal Length

Zooming
7

• Lens Types
• Standard lens f 50 mm
• Wide-angle lens f lt 50 mm
• Telephoto f gt 200 mm
• Zooming
• Compound lens can alter focal length
• 35-105 mm .

8

• Iris F-Stop

9

• Exposure Issues
• F-stop
• - 4, 5.6, 8, 11, 16, 22 .
• shutter speed
• - 1/60, 1/125, 1/250, 1/500 s .
• - crisp still image
• total exposure exposure x time
• contrast
• auto iris

10
Video Basics

• Standard
• NTSC (National Television System Committee)
• 60 Hz, 30 fps, 525 scan lines
• North America, Japan, Korea .
• PAL (Phase Alteration by Line)
• 50 Hz, 25 fps, 625 scan lines
• Europe .

11

• Color Encoding
• VHS composite
• chrominance luminance sync
• RGB separate colors
• Red green blue sync
• Red green (sync) blue
• SVHS Y/C
• Luminance chrominance

12

• Resolution
• VHS tape 240 scan lines
• SHVS tape 400 scan lines
• NTSC 525 (480) lines
• PAL 625 lines
• Frame grabber resolution
• 512 x 480
• 640 x 480 .

13

• Aspect Ratio
• Video/computer monitor 4 3
• Frame grabber
• 640 x 480 4 3 (square pixel)
• 512 x 480 (non-square pixel)
• V-to-H scale ratio computation
• Non-square pixel model
• Peak manual

14

• Sensors
• CCD (charge coupled device)
• Arrays of photo diodes
• Linearity
• Less light needed
• Electronic shuttering
• CMOS
• Cheaper
• Easy manufacturing

15

• Interlacing
• Odd field even field
• 30 frames/s 60 fields/s

1/60 s
1/60 s
1/30 s
16

• Shutter Speed vs. Frame Rate
• Frame rate
• Normal 30 frames/s, 60 fields/s
• High-speed ?
• Electronic shutter
• Shutter speed
• 1/125, 1/250, 1/500, 1/1000 .
• Sample and hold

17

• Luminance and Iris
• Minimum luminance
• Iris
• F-stop
• Auto Iris

18

• Genlock
• Multiple camera setting
• Camera synchronization
• Opens and closes shutters at the same instant.
• Genlock-equipped cameras

19

• Time Code Generator
• Horita models
• Generates SMPTE (Society of Motion Pictures and
  Television Engineers) time codes
• HHMMSSFF
• Inserts both video audio codes

20
Motion Analysis System
RGB Monitor
Computer
VCR
COM2
Frame grabber
Composite
RGB
Serial communication