# 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
 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