A Samsung SCO-2080R Analog Bullet Camera’s specification overview is like this-
• High resolution of 600TV lines (Color), 700TV lines (B/W)
• 1/3″ Super HAD color CCD
• Min. illumination 0Lux (IR LED On), IR distance 50m
• Built-in V/F lens (2.8 ~ 10mm)
• True Day / Night (ICR), MD, SSNRIII
• IP66, Coax : Pelco-C (Coaxitron), RS-485
• Dual power, 24V AC & 12V DC
An ACTi D64, IP Camera’s specification overview is like this-
• 1 Mega Pixel
• 1/4″ CMOS, Progressive Scan
• Day/Night IR, Indoor Dome, Mechanical IR Cut Filter
• Minimum illumination of 0 lux with IR LED
• Electronic Shutter 1/5 ~ 1/2,000 sec (manual mode); 1/5 ~ 1/10,000 sec (auto mode)
• Built-in f2.8 to 12mm / F1.4, varifocal lens
• 30 fps at 1280 x 720 resolution
• Selectable H.264 HP and MJPEG compressions with dual streaming
• Video motion detection
• Powered by PoE Class 2
Types of CCTV Camera
Based on its construction, environmental consideration, and purpose to use manufacturer design different type of cameras.
Indoor Camera: Indoor type cameras are design to use in indoor areas only. They are not design to sustain in harsh environment.
Outdoor Camera: They are design to sustain environmental changes. Like weatherproof, waterproof, dust-proof etc.
Bullet Camera: It has a cylindrical shape. It may be Indoor or Outdoor type.
Dome Camera: It has dome shape housing.
Box Camera: Generally, the box camera comes without lens. You have to purchase the lens separately. It’s generally used in indoor but can be used for outdoor with a housing.
Vandal Proof Camera: A vandal-proof camera intended to resist vandalism. One can’t break or impair its function easily.
IR Day/ Night Camera: It has infrared LEDs to capture image in dark. The image captured in dark using IR LEDs is black and white.
Hidden Camera/ Covert Camera: It doesn’t look like a CCTV camera rather it comes in different shapes like smoke detector, sprinkler, sensors etc.
PTZ Camera: Its Pan Tilt and Zoom can be controller remotely.
Surround / Panoramic View Camera: You can monitor 360 degree by this camera. These are of two types.
1. Multi Lens Camera: Multiple lenses combined together and send videos over a single cable.
2. Fish Eye Lens Camera: A single lens capture a 180 degree or 360 degree images.
Thermal Imagine Camera: All objects, including human bodies, emit electromagnetic radiation. The wavelength of radiation emitted depends on the temperature of the objects. A thermal imaging camera forms an image using electromagnetic radiation, similar to a common camera that forms an image using visible light. It can capture images even in complete darkness.
LPR/ ANPR: License Plate Recognition or Automatic Number Plate Recognition cameras are used to capture and record vehicles license plate number. An LPR camera must have high shutter speed and high frame rates. Fast shutter speed reduces motion blur. A software used for optical character recognition and save license numbers on computer drives.
CCTV Camera Elements
CCTV Camera Lenses
There are three main types of lenses-
Fixed lens: Such a lens offers a fixed focal length. Like 2.5 mm, 3.6 mm, 6 mm etc.
Varifocal lens: This type of lens offers adjustable focal lengths. Like 2.8 – 12 mm, 3-8 mm etc.
Motorised Zoom lens: Motorised Zoom lenses are like varifocal lens, with an option to control its focal length from a distance location.
There are different type mounts depending sensor board. The two types of mounts C & CS are generally used.
CCTV Camera Sensors
Light falls on image sensor through lens. Sensors produce equivalent electrical signals. Further circuitry converts this electrical signal to video signal. Mainly two types of sensors are used – CCD and CMOS.
CCD Vs CMOS:
– CCD (Charged Coupled Device)
– CMOS (Complementary Metal Oxide Semiconductor)
Both the sensors have their own strengths and weaknesses. However in the present days manufacturer are focusing more on CMOS because its production is cheaper than CCD. The CCD has better light sensitivity but consumes more power and expensive than CMOS.
Image Resolution
Image Resolution is actually detail of an image. Analog picture resolution measured in terms of TV lines or TVL. The TVL is defined as the number of alternating light and dark vertical lines counted horizontally in the length equal to the height of the monitor. Suppose a monitor is 30 cm (width) x 23 cm (height), then TVL is vertical light and dark lines present in 23 cm space taken horizontally (skip 7cm).
Digital image resolution is the number of pixels used to develop an image. It is the capability of the sensor to measure the smallest object clearly. The CCTV Camera sensors come in different resolutions like 1 Mega Pixel, 2 Mega Pixel etc. We multiply number of horizontal pixel to the number of vertical pixel to get the image resolution. Like, HD resolution 1920 X 1080 = 2’073’600 Pixel (= 2 Mega Pixel).
Common CCTV Camera/ Monitor resolution format-
| Format | Pixel (Horizontal x Vertical) |
| QQVGA | 160 x 120 |
| QVGA | 320 x 240 |
| VGA | 640 x 480 |
| SVGA | 800 x 600 |
| NTSC | 720 × 480 |
| PAL | 720 × 576 |
| XGA | 1024 × 768 |
| HD (SMPTE 296M) | 1280 x 720 |
| 1 MP (SXGA) | 1280 x 960 / 1280 x 1024 |
| 2 MP (UXGA) | 1600 x 1200 |
| HD (SMPTE 274M)/ FHD | 1920 x 1080 |
| 3 MP | 2048 x 1536 |
| 4 MP | 2560 x 1600 |
| 5 MP | 2560 x 2048 / 2592 x 1920 |
| UHD | 3840 x 2160 |
* QQVGA-Quarter QVGA, QVGA-Quarter VGA, VGA-Video Graphics Array, SVGA-Super VGA, NTSC-National Television System Committee, PAL-Phase Alternating Line, XGA-Extended Graphics Array, SXGA-Super XGA, UXGA-Ultra XGA, HD-High Definition, FHD-Full HD, UHD-Ultra HD
Choosing a Lens; Image Resolution at a distance
A lens produces images in the form of a circle, called the image circle. In a CCTV camera, the imaging element has a rectangular sensor area (the image size) that detects the image produced within the image circle. The ratio of the length of the horizontal to vertical sides of a video image is called the aspect ratio, which is normally 4:3 (Horizontal: Vertical) for a standard CCTV camera.
The sensor size expressed in “inch” (such as 1/4″, 1/3″, 1/2″, 2/3″ and 1″), measured diagonally. The inch-based sensor format is non-standardized. Their exact dimension varies on manufacture to manufacturer (sensor format express in approximately 1.4 times the length of the diagonal of the actual sensor size.)
“For example, a camera advertising a 1/2.7″ sensor does not have a sensor with a diagonal of 0.37″ or 9.4 mm; instead, the diagonal is closer to 0.26″ or 6.7 mm.”
| Sensor Format | Aspect Ratio | Diameter | Actual Diagonal (mm) | Width (mm) | Height (mm) |
| 1/4” | 4:3 | 6.300 | 4.500 | 3.600 | 2.700 |
| 1/3.6” | 4:3 | 7.056 | 5.000 | 4.000 | 3.000 |
| 1/3.2” | 4:3 | 7.938 | 5.680 | 4.536 | 3.146 |
| 1/3” | 4:3 | 8.467 | 6.000 | 4.800 | 3.600 |
| 1/2.8” | 4:3 | 9.000 | 5.947 | 4.788 | 3.528 |
| 1/2.7” | 4:3 | 9.407 | 6.721 | 5.371 | 4.035 |
| 1/2.5” | 4:3 | 10.160 | 7.182 | 5.760 | 4.290 |
| 1/2” | 4:3 | 12.700 | 8.000 | 6.400 | 4.800 |
| 1/1.8” | 4:3 | 14.111 | 8.933 | 8.500 | 6.800 |
| 1/1.7” | 4:3 | 14.941 | 9.500 | 7.600 | 5.700 |
| 2/3” | 4:3 | 16.933 | 11.000 | 8.800 | 6.600 |
| 1” | 4:3 | 25.400 | 16.000 | 12.800 | 9.600 |
| 4/3” | 4:3 | 33.867 | 22.500 | 18.000 | 13.500 |
| 1.8” | 3:2 | 45.720 | 28.400 | 23.700 | 15.700 |
Filed of View
W = width of object
H = height of object
d = distance to object
w = width of image sensor
h = height of image sensor
f = focal length
Horizontal Field of View (HFOV) = Camera Distance x (Sensor Chip Width / Focal Length) = d x w/f
Horizontal Resolution= Number of Pixel (Horizontal) / Horizontal Field of View
Angle of View = 2 tan-1 h/2f
Example:
For an HD resolution (1920×1080), 12mm Lens and ¼” sensor format
Chip Width =3.6mm and Horizontal Number of Pixel = 1920
Suppose we are interested to find image resolution at a distance of 20 ft.
Then, HFOV= 20ft x 3.6mm/12mm = 6 ft.
So, the Horizontal Resolution = 1920/6 = 320 pixel/foot at 20ft distance
Similarly we can find the Vertical Resolution.
Interlaced and Progressive Scanning
In the Interlaced Scanning, half the picture appears on the screen at a time. The other half of the picture follows an instant later (1/60th of a second, to be precise for NTSC system).
In the Progressive Scanning, the entire picture is produced at once.
Symbol “i” stands for interlaced and “p” for progressive scan like, 480i, 720p, 1080p etc.
Shutter Speed, Motion Blur, Sense-Up and F-Stop
Shutter speed is the length of time a camera shutter is open to expose light into the camera sensor to capture an image. Fast Shutter speed reduces light sensitivity but it can help to capture moving objects, like a moving vehicle. LPR cameras require high shutter speed to capture the licence plate number of a moving vehicle. If the shutter speed is slow, it can create an effect called “Motion Blur”.
Sense-Up settings allows us to select digital slow shutter (DSS) speeds in order to allow extra light onto the sensor to provide better sensitivity in low light conditions. Sense-up can range from 2x to 128x or more. The 2x means the light being allowed to hit the sensor two times the normal light setting and so on.
The Focal-STOP (f-stop, focal ratio, f-ratio, f-number, or relative aperture) is the measurement of the aperture setting in a camera lens, similar to the eye pupil. The fundamental use of the f-stop is to determine how much light is passing through the lens and onto the image sensor. This will result in increase or decrease of brightest of the picture we are capturing depending on value of the f-stop. The f-stop is the focal length of the lens divided by the diameter of its opening.
i.e., N = f/D, where f is the focal length and D is the diameter of the entrance pupil.
Each consecutive f-stop halves the opening of the previous. For example, a 12 mm lens with its f-stop set to f2 means that the optics inside the lens creates a diameter (12mm/2) equivalent to 6 mm. Changing the f-stop to f4 creates a diameter(12mm/4) of 3 mm.
Iris
To provide optimum performance neither too much nor too little light should fall on the camera sensor. This can be adjusted by means of the lens iris.
A smaller iris opening offers greater depth of field and better focus, but the reduced amount of light admitted into the camera results in poor quality images in low lighting levels.
Fixed Iris: No adjustment to different lighting conditions and therefore is not suitable for applications where fine detail is consistently required.
Manual Iris: Can be adjusted at the time of installation, allowing an optimum picture to be obtained for a fixed lighting level.
Auto Iris: Two type of auto iris are there DC iris and Video iris. Both have a motor-driven, automatically adjustable iris opening that responds to changes in light levels. Both also use an analog signal to control the iris opening. In a DC-iris lens, the control circuit resides inside the camera but in a video iris, the control circuit is inside the lens. A new technology P-Iris is being used these days. It is improved version of auto iris.
Light Sensitivity
Light sensitivity, or minimum illumination, refers to the smallest amount of light needed for the camera to produce an image of useable quality. Minimum illumination is presented in LUX (Lx), which is a measure of luminance. If the amount of light is insufficient, the image will be noisy or dark.
Following is the chart of lighting vs approximate lux level-
| Condition | LUX |
| Sunlight | 100,000 |
| Full Daylight | 10,000 |
| Overcast Day | 1’000 |
| Very Dark Day | 100 |
| Twilight | 10 |
| Deep Twilight | 1 |
| Full Moon | 0.1 |
| Quarter Moon | 0.01 |
| Star Light | 0.001 |
| Overcast Night | 0.0001 |
-1 Footcandle (fc) = 10.76 LUX (lx)
IR cut Filter and ICR
Infrared (IR) cut-off filters are used to produce accurate colour images. An IR cut-off filter blocks the transmission of the infrared light while passing the visible light. The IR cut filter is not desirable in monochrome mode. In this case ICR or Infrared Cut filter Removal is used. With ICR, the filter is removed which allows for much greater IR sensitivity in monochrome (B&W) mode.
BLC and WDR
BLC or Back Light Compensation allows the camera to adjust the exposure of the subject properly in case of background light. WDR or Wide Dynamic Range, results better than BLC, because it handles multiple exposure zones to give both the high light and low light areas a proper exposure.
DNR (Digital Noise Reduction)
Noise reduction is the process of removing noise from a signal. DNR (Digital Noise Reduction) or SNR (Signal Noise Reduction) is a process which uses a digital filtering algorithm (known as digital comb filter) on the digital image data to reduce the amount of random noise.
2D DNR finds noise and refers to neighbouring pixels to compensate it. This method is effective to noise reduction of video sequence of a moving object, but may produce blurred pixels for static portions of the image, such as background.
3D DNR employs inter-frame reduction which refers to the previous and next frames’ pixel values for noise processing. This method is effective to reduce noise on a fixed subject such as background, but may produce blurred effects to the moving object in the video sequence.
Some manufacture combined these both techniques to produce better results, like Samsung SSNR III (Samsung Super Noise Reduction), by separating moving and static parts and applying 2D DNR and 3D DNR methods respectively.
OSD Menu
Some manufacturer provides OSD or On Screen Display menu to adjust camera setting and visually display on screen.
Moving Electron 