Camera/Video
1/3”
CCD DSP
lux
3.6 mm f/1.2
70 deg.
Definitions
radiometric vs. photometric
• Photometry is just like radiometry except that everything is weighted by the
spectral response of the eye
• Luminance (cd/m2)-Describes the amount of light that passes through or is emitted
from a particular area, and falls within a given solid angle.
• Luminous flux (lm)- The measure of the perceived power of light. It differs from
radiant flux, the measure of the total power of light emitted, in that luminous flux
is adjusted to reflect the varying sensitivity of the human eye to different
wavelengths of light.
• Lux (lx = lm/m2)-is the SI unit of illuminance, and measuring luminous flux
per unit area.
QUANTITY RADIOMETRIC PHOTOMETRIC
QUANTITY
RADIOMETRIC
PHOTOMETRIC
power
watt (W)
lumen (lm)
power per unit area W/m2
lm/m2 = lux (lx)
power per unit
solid angle
W/sr
lm/sr = candela (cd)
power per area per
solid angle
W/m2-sr
lm/m2-sr = cd/m2 = nit
Illuminance of surfaces illuminated
by:
(Power/Area, Intensity)
0.0001 lux -Total starlight
0.002 lux -Moonless clear night sky
0.01 lux - Quarter moon
0.27 lux -Full moon on a clear night
1 lux - Full moon overhead at tropical latitudes
Focal length-f
The focal point of a lens is defined as that point at which rays
from infinity (parallel rays) impinging on the lens are focused.
The focal length is the distance of the focal point from the
center of the lens.
F number
• In optics, the f-number is given by f/D where f is the
focal length, and D is the diameter of the entrance
pupil
• Ex. f =100 mm and D = 25 mm 100/25 = f/4
• Ex. f= 200 mm and D = 50 mm 200/50 = f/4
• The 200 mm lens's f/4 opening is larger than that of
the 100 mm lens but both will produce the same
illuminance in the focal plane when imaging an
object of a given luminance.
FOV (Field of View)
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FOV underwater
Angle of coverage (FOV)
α = 2*tan-1(d /2f)
Note small f large α
α=80° Field of View
α=8° Field of View
Snell’s Law
Diagonal coverage of lenses
on the 35mm format
The refractive index of (sea)
water was taken to be 1.339
for underwater (UW)
Focal Length Coverage in
(mm)
Air
(degrees)
Coverage
UW (Flat
Port)
degrees
19
97.42
68.27
20
94.49
66.51
24
84.06
60.00
28
75.38
54.34
30
71.59
51.80
α' = 2 sin-1[ Sin(α/2) / nw ]
The port itself has no effect on the angle of coverage (although it does alter the effective
position of the lens entrance pupil as seen from outside the housing). Derivation
CCD-Charged Coupled Device
Type
Aspect
Ratio
Diameter
(mm)
Diagonal Width
(mm)
(mm)
Height
(mm)
1/3.6”
4:3
7.056
5.00
4.00
3.00
1/3.2”
4:3
7.938
5.68
4.536
3.416
1/3”
4:3
8.467
6.00
4.6
3.6
The type designation harks back to a set of standard sizes given to TV camera tubes
in the 50's. These sizes were typically 1/2", 2/3" etc.
Depth of Field
If one moves a real film plane back and forth a bit, a range of object distances remains in
acceptable focus, this is the depth of field
Focus the camera on the far tree.
Near tree out of focus
Image distance vs. object distance
If the object becomes closer to the lens, the image moves further away from the lens
and becomes larger.
One can change the depth of field by changing the focal length or aperture size of the
lens. The width of the non-converged beam for the near-tree image becomes much less,
and can be made too small to notice. Then both trees will be in acceptable focus.
CCD-Charged Coupled Device
• CCD Overview
• Animation
• DSP-digital signal
processing
The signal processor within the camera receives the
information from the charged coupled device, or CCD, and
combines it into video frames
Some Calculations
Outland UWC-325/p
• Focal length
f=3.6 mm f/1.2
Using f/1.2=f/D and solving for D
D= 3.6/1.2= 3 mm
• FOV
α = 2tan-1(d / 2f)=2tan-1(6/(2*3.6)) = 79.61o
Notice that a small f gives a larger FOV
• Underwater FOV using nw=1.339
α' = 2sin-1[ sin(α/2) / nw ]=2sin-1[sin(80/2)/1.339]= 57.3 o
High-definition video or HD video is any video system
of higher resolution than standard-definition (SD)
video, and most commonly involves display resolutions
of 1,280×720 pixels (720p) or 1,920×1,080 pixels
(1080i/1080p).
640 x 480 Pixels with 4:3 Aspect
Ratio
1920 x 1080 Pixels with 16:9
Aspect Ratio
Camera
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Outland Technology
Seaview
Remote Ocean System
Insite
GoPro
GoPro 3D
Camera Potting
OceanPro HD
• Deepsea Power and
Light
• Lights-camera-action
Glossary
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f = F number
f= focal length
D = diameter of apature
α = Field of View in air (FOV)
α’ = Field of View in water
d = diagonal of imaging device