Cameras and Optics

Objectives
  • Demonstrate an understanding of (and how they interact with each other)
    • Depth of field
    • Exposure time
    • Shutter speed
    • Frame rate
    • Aperture
    • F-stop
  • Demonstrate an understanding of how video information is stored on miniDv tapes
  • Demonstrate how to adjust the above characteristics on typical digital video cameras

Photogrammetry

  • Field of View
  • Exposure Time
  • Frame Rate
  • Focus
  • Depth of Field
  • Aperture
  • f-stop
  • Focal Length
Photogrammetry
Standard Photographic Apertures, Exposure Times, and Film Speeds
APEX value 0 1 2 3 4 5 6 7 8 9 10
Aperture (f-stop) 1 1.4 2 2.8 4 5.6 8 11 16 22 32
Exposure time (s) 1 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/1000
Film Speed (ISO or ASA) 3 6 12 25 50 100 200 400 800 1600 3200
APEX stands for the Additive Photographic Exposure System. Each increase in APEX value indicates a decrease in the light level by one-half.

Each faster film speed requires half the amount of light that the previous speed needed for proper exposure.

Binary Data

00000000 = 0 00000001 = 1 00000010 = 2 00000011 = 3 00000100 = 4 00000101 = 5

11111111 = 255

-Photoshop Example of RGB data

MiniDV

  • Data rate of 25Mbps = 3.125MB/s
  • 1 frame of video = 720 x 480 = 345,600 pixels
  • 30 frames of video per second
  • 60 fields of video per second
  • This would be 345,600 pixels (8 bytes x 3 colors) x 30 frames = 248Mbps

How does that much information fit when only the data rate is only 25Mbps?

Helical Scanning