Welcome!

3.1.2.1.1 APERTURE

The value of Aperture is measured in “F” number (f-number), which indicates the “opening” of lens, the area which allow light to pass through the lens that is control by iris. If the value of “F” is low, higher is aperture that means in result more light allowed to pass through the lens. F-number also shows the brightness of images least f-number more the image bright. [17]

3.1.2.1.2 MAXIMUM APERTURE

This is a lowest value of “F” for any particular lens or maximum size at which diaphragm of lens can open. Which allow light to pass through from lenses. [17]

3.1.2.1.3 ANGLE OF VIEW

Least value of focal length give wider angle of view, it can be expressed in diagonal, horizontal or vertical. [17]

3.1.2.1.4 Automatic Level Control (A.L.C)

Some time there are bright spots in the field of view either by exposing or by taking an average across the entire scene. Automatic level control function allows iris compensation for the bright spots with in the field of view. [17]

3.1.2.1.5 AUTO-IRIS LENS

Some lenses are designed that they automatically controlled and maintain a uniform level of light throughout changing various light conditions.  This automatic control is done electronically.[17]

 3.1.2.1.6 BACK FOCUS

Back focus terms is used to describe relationship between the distance of image capturing device CCD and lens iris. This distance is very important while capturing image as maintaining proper depth of area through changing focal length and changing lighting conditions. Back focus is achieved by proper adjustment of image capturing device CCD or lens collar in the camera itself. It is very much important when zoom lenses are used to maintain a correct focus throughout zooming range. This term also referred as “tracking”.[17]

3.1.2.1.7 "C"-MOUNT

"C"-MOUNT is an industry standard for mounting a lens to the camera i.e. barrel size should be 1 inch diameter and it should be 32 threads in one inch. The distance between mounting surface and sensor should be 0.69 inches. C mount lens can also used on CS-mount camera by adding an adopter ring, but CS-mount lenses can not be used on C-mount camera.[17]

3.1.2.1.8 "CS"-MOUNT

It is a new standard in the camera industry, it is almost same standard like of C-mount with only difference of distance between mount point and image sensor. In CS mount lens has one inch diameter barrel with 32 threads in one inch but CS-mount sensor is located 0.492 inches behind the mounting surface, where as C-mount sensor is located 0.69 inches behind the mounting surface. Due to shorter distance design a CS-mount lenses can not be mounted on C-mount camera.[17]

3.1.2.1.9 DEPTH OF FIELD                                                                             

It is area in front and behind the focus distance where image remains in focus. The greater the values of aperture (f) indicate more depth of field. Scene lighting and lens aperture are greatly influences the depth of field.[17]

3.1.2.1.10 EXTENSION TUBES

Extensions tubes are spacers which are placed between camera and lenses, used to reduce the minimum object distance. [17]

3.1.2.1.10 F-STOP

F-Stop term is used to indicate the speed of the lens. F-stop and f-number some time have same meanings as both term used interchangeably. Smaller the f-stop more light pass through aperture and which object is in focus gives the clear view but not behind. As shown in fig-11 below when f-stop set to 5.6.[17]

Fig-11

When f-stop is very high or set to maximum value it capture all front and back images in focus. As shown in fig-12, when f-stop set to 32. [17][18]

Fig-12

3.1.2.1.11 FIELD OF VIEW

Field of view is the maximum angle of view that can be seen through the lenses. It could be in either direction i.e. horizontal or vertical or it is the maximum size at a given length from the camera to object.[17]

3.1.2.1.12 FIXED LENS

The fixed lens term is used for the lenses whose focal length can not be changed. These lenses have fixed area under view.[17]

3.1.2.1.13 FOCAL LENGTH

Focal length means the distance between the center of lens and place where sharp image of the object is viewed. Focal length of a camera indicates how much magnifications a lens can provide. Larger the focal provide higher magnification which able to see a long distance object at near place. Short the focal length will be able to see a wide angle view on a particular scene i.e. less level of magnification.[17]

Calculating Lens Focal Length

1) f = v x (D/V)  or  2) f = h x (D/H)

f :  focal length of lens

V: Vertical field of view

H: Horizontal field of view

D: Distance from Lens to Object

v : vertical multiplier (see table below)

h : horizontal multiplier (see table below)

Table …A

Once calculation example:

To calculate focal length using:

2/3 inch camera            v = 6.6

Vertical field of view     V = 500 mm

Distance from lens to object      D = 3500 mm

As we have “V” vertical field of view value is available then by using the formula

 f (focal length) =  v (vertical multiplier) x D (distance of object from lens) / V (vertical field of view)

By substitute values

f = 6.6 x (3500/500) = approx 46 mm

Therefore, specify a 46mm lens to achieve a 500mm vertical f.o.v. from 3500mm object distance with 2/3" format camera.

Note: f.o.v. (V or H) and object distance (D) can be in any units of measure, provided they are both the same. [19]

3.1.2.1.14 FORMAT

Format means approximate size of a camera image detection device. This term is used to indicate the size of lens which can be used on different types of cameras. Like 1inch format lens work on 1, 2/3, 1/2, 1/3, 1/4 inches and down size cameras. It is necessary to use specified format lens in particular camera as small format lenses on large cameras created distortions in result having poor back focus. [17]

3.1.2.1.15 IRIS

The "iris" is a mechanical device that control the opening and closing function of a camera aperture. There are various kind of control of iris comes that may be fixed, manual, or voltage controlled. Some new additional circuit in an Auto Iris lenses allowing the operator to switch to full control of the iris, from maximum to minimum aperture. This is very much useful for various lighting situations such as strong backlighting. This additional auto iris control function is call “iris override”. Some of the lenses in which iris can be fixed manually those lenses are call manual iris lenses.[17]

3.1.2.1.16 LINE SCAN LENS

These are special lenses which are used only to scan lines in documents and design drawings.[17]

3.1.2.1.17 LUX

LUX is the unit of illumination in which the meter is the unit of length. It is equal to the illumination of a surface one meter away from a single candle. One lux equals one lumen per square meter. 10 lux equals 1 foot-candle.[17]

3.1.2.1.18 MACHINE VISION LENS

These are special lenses with sensors which are used to control various processes in a factory for automation purposes. These lenses are designed to increase the over all performance.[17]

3.1.2.1.19 MINIMUM OBJECT DISTANCE (M.O.D.)

This is the minimum distance which a lens can focus on. If lenses have smaller focal length they have small M.O.D. This distance can be varied by used of different extension tubes.[17]

3.1.2.1.20 MONOFOCAL LENS

These are lenses which focal length can not be changed. Normally used to capture the fixed field of view. [17]

3.1.2.1.21 PINHOLE LENS

These are special small lenses which are used primarily in covert applications where the camera or lens must remain hidden. [17]

3.1.2.1.22 PRESETS

Some lenses have default position settings of the zoom, focus, and iris for this  potentiometers built into the lens. [17]

3.1.2.1.23 UV LENS

“A lens intended for use with wavelengths shorter than about 380 nm. It must be made of aquartz or some other material transparent to ultraviolet radiation, as glass is opaque in that region. ” [17]

3.1.2.1.24 VARIFOCAL LENS

Lenses whose focal length adjusted manually to get desired magnification.[17]

3.1.2.1.25 ZOOM

“The ratio between a lens maximum and minimum focal length, like the lenses having  12 to 240mm size has a zoom ratio of 20 times (240/12 = 20).” [17]

3.1.2.1.26 ZOOM LENS

Lenses whose focal length changed either manually or by motorised method. These lenses are used to cover varieties of needs. [17]

3.1.2.2 CCTV Normal Lenses (fixed focal lenth or Fixed Zoom)

            It is very important while selecting of CCTV camera with respect to its use ability. It depends up to what distance need to be monitored, as long distance lenses are very costly. Most of the cameras are equipped with standard zoom lenses which cover distance range between, 10 to 20 or up to 50 meters, which is considered to be normal range. All the high range lenses are specifically designed for long distance surveillance both in day and night where infrared illumination is used. These lenses are specially designed to get a high quality image both in day and night time without any problem.

There  are special lenses which remain in focus in day and night vision and in under illumination these lenses are called aspherical IR varifocal lenses. These are high performance lenses, which gives clear and sharp picture even in day and in night.

Presently these lenses considered to be ideal lenses for true day and night surveillance. These lenses are very easy to install and need no special experience.

Aspherical Varifocal Lense

                                                                                               Fig-13  

If we comparison of focal length with the distance of monitoring of same format lens i.e 1/3”, we se a major difference of quality of image as shown in the image below.

Fig-14.

As in the fig-14 when the focal length of the same format (1/3”) lenses increases the picture quality become better and better. At the focal length of 2.8mm at a distance of only 2 meter the picture seem to be very far and it is not possible to view the image at distance of 50meter. Comparatively if the focal length of 1/3” format lens is increase to 50mm the image even at 50 meter come nearer and easily distinguished. These lenses have a fixed focus and after one time the focus is set according to user requirement then it is fixed by screw. The use of these lenses limited in the area where there is no variable focus is required. It is very important factor which distance is to be monitored. Proper selection of equipments saves a lot time and efforts which result a better quality.

The importance of CCTV increasing day by day, as new more powerful and motor operated lenses are available which gives much better results even in x100 meters. In this regard the new high resolutions cameras in which high capacity megapixel CCD is used to get best quality images is considered to be most important as compared to the price. In the present age technology is upgraded very fast to meet the market demands where surveillance and security is considered to be more important then cost. New market demands to get better and crystal clear image even in kilometres, create new opportunities to develop new advance better quality equipment. New advance digital image capture, compressions and transmission technologies set the new standard for high performance megapixel CCTV cameras making its market exponentially.  All these high performance quality efforts and benefits of megapixel CCTV cameras create a good trust for the manufacturers, sellers, installers and to the end users. Now new standards are set for the CCTV market for the next generation.

While defining the quality of lenses Albeit appreciate the Tamron a lenses manufacturing company, they said this is really a crucial element that this company is achieving 100% of quality images potential produced by the most modern mega pixel cameras which are using high quality lenses. That’s where the development of new lenses takes place in companies like Tamron. All high performance Varifocal lenses in 1/3 inch format are specifically designed to give best quality images from the cameras which are equipped with mega pixel CCD sensors. [16]
National Sales Manager Steve Beaulieu of industrial optics division of Tamron USA also expresses his views about CCTV cameras importance in way.

The total share of mega pixel CCTV cameras in the present security surveillance market is very less as compared to the normal cameras. The main concept of the end users they consider that their present system is good and enough for their needs but in actual they are spending more money on the old system as compared to the new system. If we compare the key functions of modern CCTV cameras with old there are a lot of significant economic as well as technical advantages come to attract the consumer behaviour. This is in fact that level of security in a given system is said to be directly proportional to the value of information it can capture. In place of four standard normal CCTV cameras only two wide angle lenses mega pixel CCTV cameras are enough and which saves a lot of time and efforts, in result less operative and maintenance cost.[16]
The most modern digital zooming technology added another feature; the image captured by mega pixel camera, recorded in DVR does not become pixilated and degraded as this normally happen with conventional cameras, in result zoom to high higher magnification gives good picture quality. [16]
The image capturing quality of megapixel cameras really very good, as Steve Beaulieu said. 

“When you put it all together, the overall imaging and operational advantages of mega-pixel cameras are awesome,” notes Beaulieu, “but we’ve got to get beyond the old ‘that’s good enough’ philosophy that pervades the security industry. This will entail education on the part of manufacturers, distributors, system integrators, and installers, but I’m confident that end-users will get the message. Indeed, many of them already have. I’m pleased to say Tamron is doing its part, and the new line of Tamron 1/3-inch format mega-pixel-compatible Vari-Focal lenses represent a significant breakthrough, extracting the maximum performance from surveillance cameras equipped with mega-pixel count image sensors.”
Tamron’s dynamic new optical duo.
“The first in what is informally known as the MP (mega-pixel-compatible) series is the Tamron 2.4-6mm F/1.2 and 3.0-8mm F/1.0 Vari-Focal lenses, each available in both manual and DC Auto Iris models,” explains Beaulieu. “Both feature advanced optical designs employing aspheric elements and LD (low dispersion) glass to minimize aberrations and deliver superb image quality, with uniformly high resolution and contrast from the center to the edges of the image field. In order to achieve results of this caliber, all the optical components of Tamron MP lenses are manufactured and assembled to extraordinarily tight tolerances. According to our own laboratory measurements in Japan, resolution in the corners of the image field is almost twice as high as that of conventional lenses—a spectacular achievement that is crucial at the ultra-wide-angle settings often used in surveillance systems. In order to enhance contrast and freedom from ghosting and flare even under adverse lighting conditions, both these lenses have state-of-the-art multi-coating applied to all glass surfaces.”

“In addition to delivering the goods in terms of sheer optical excellence, these Tamron Mega-Pixel Varif-Focal lenses have many unique practical and operational advantages,” explains Beaulieu. ‘Both are remarkably compact, enhancing ease of installation in tight spaces The extra light-gathering capability of the super-speed F/1.0 aperture on the 3.0-8mm supports even mega-pixel sensors with low sensitivity, allowing them to be used in dimly lit environments. The ultra-wide focal length range on the 2.4-6mm, which provides an amazing 111° angle of view at the widest-angle (2.4mm) setting, allows surveillance of an entire room when positioned in a corner. Finally, the mechanical construction of the series is of the highest caliber, with rugged, durable, high-quality components throughout, and precision helicals that turn about 200 degrees over the entire 0.3m-to-infinity focusing range (rather than 40-50 degrees as on competitive lenses). This last feature makes it much easier to make precise focusing adjustments, which are especially critical in achieving optimum imaging performance with mega-pixel cameras.”

“What this all boils down to is value,” concludes Beaulieu. “These new Tamron Vari-Focal lenses for mega-pixel CCTV take this emerging imaging category to a whole new level. And amazingly they’re moderately priced, fitting into the middle range of competitive offerings. We know from the feedback we get from the field that Tamron CCTV lenses are universally acclaimed for their reliability, durability, value, and consistently high performance. You can rest assured that these two lenses will uphold and enhance that reputation. Plus, but we’ve got some equally exciting new Tamron MP Vari-Focal lenses in the works that will round out the line, and extend the range of what’s possible in this vibrant emerging sector of the surveillance/security market.”[16]

                   Video images shown below were shot using actual monitoring megapixel compatible cameras and normal CCTV lenses.

Fig-15

If we compare the both image from centre and corner we can see a major quality difference in mega pixel cameras as compared to normal conventional CCTV lenses. In security and surveillance the important thing is quality of image captured and the second major thing is distance and area covered, in mega pixel lenses cameras good quality images capturing from corners gives an added advantage with respect to its quality imaging.

In CCTV technology the lenses required which provide high performance in all weather conditions, low light, in high light, angle of coverage, distance covered and there focus did not effect for any of the condition.

3.1.2.3 CCTV Zoom Lenses
If look around the definition of zoom as it is measured in X factor now it need to be answer here what is zoom factor “X” which is used to described the power of lens. It is the ratio of highest to lowest focal length. For example if we have a lens whose focal length is marked as 18 to 55, with the describe formula if we take the ratio of 55/18 the answer is 3.06 approximately we can say this lens has 3x zoom.[24]
In case of telephoto lenses this term is bit confusing as these huge size lenses has same minimum and maximum focal length, e.g. if we have 600mm telephoto lens which has same minimum and maximum focal length then this ratio will give value as 600/600= 1x optical zoom , but this lens has very high value of zoom power and very good quality of image.[23]
“As a conclusion, the “X” optical zoom is not what most people think it is and the bigger is the number in front of the “X” on the case of your camera, the more will suffer the final image that passes through your lens.”[23]

3X optical zoom The Canon 18-55 f/3.5-5.6 USM lens

Fig-16

1X optical zoom The Canon 600mm f/4L IS USM lens

Fig-17

There are a lot of manufacturing companies making good quality zoom lenses. Some famous companies list given below.
Computar
Fujinon
Kowa
Pelco
Pentax
Schneider Optics
Senko
Tamron
In additions to these companies there are some other companies who engage in making good quality software applications and hardware equipments for controlling these lenses. Most famous of them are,
Image Labs
Pelco
These companies also produced hardware which provides control to control the zoom lenses. [19]

CCTV motorized high resolutions lenses are uses where a large area is need to be monitored. The objective and use of these lenses is specifically very important with respect to security and surveillance. With respect to quality and use of these high resolution lens CCTV cameras is limited & specifically predefined due to their importance this factor make price of lenses very high as compared to normal CCTV lenses.

These lenses are special purposes lenses providing 6x to 34x or more optical zoom. These lenses are controlled by DC motor through special software and hardware. In security and surveillances the importance of zoom lenses increases due to monitoring the long range distance.  At present high resolution and maximum optical zoom lenses are widely used to monitor the public places and keep an eye on running traffic.

A general example of zoom lens at different focal length.

3.1.3 Special CCTV Cameras
 These are some special CCTV cameras which are used for special purposes like some are normal which works only in day light but with additions of software and hardware changes some give very good performance in both day and night, some are very high colour sensitive and some have the capacity of heat sensitivity all these cameras are now brief discuss here in this part of this chapter.

3.1.3.1 Day & Night Vision CCTV Cameras
 This is the special feature of these cameras that they provide very good visibility in both day and night. For this the technology used is infrared technology. It is very important to understand the basic principle of night vision. The light travel in waves, some waves have shorter wave length and some have higher. Then there is some part of light which is visible but there is a part of light which is not visible i.e. ultra violet and infra red are the parts of light which are not visible light. The spectrum next to the visible light is infrared spectrum as show in fig-19.

Fig-19

As show in fig-19 the infrared has smallest part of spectrum. With respect to structure of infrared light it is divided into three parts.

3.1.3.1.1 “Near-infrared (near-IR)

Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter.[25]

3.1.3.1.2 Mid-infrared (mid-IR)

Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls.[25]

3.1.3.1.3 Thermal-infrared (thermal-IR)
Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns. The key difference between thermal-IR and the other two is that thermal-IR is emitted by an object instead of reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level.” [25]

In an atom when it got energy from outer source its electron go to outer shell after absorbing energy. The outer shell electrons (high energy electron) always try to come back in the lower shell and in result it emit energy in the shape of photon or light energy. “The photon emitted has a very specific wavelength (colour) that depends on the state of the electron's energy when the photon is released.”[25]

These photons (infrared light) are not visible with the normal eyes, therefore special lenses are used to collect these photon from all of the objects which are in view. The infrared light which first send in night in pulses through infrared devices and collected back through special lenses which after processed create an image. The quality of image depends upon the intensity of the infrared emission.

There are various types of night vision cameras are available from various knownable manufactures in market, some have inbuilt infrared LEDs or where more surveillance is required external high performance infrared devices are also attached. As shown in fig-20, 21 and 22 below.

Fig-20 Normal fix lens normal range IR CCTV camera  (built in IR LEDs)

IR technology gives a new concept of Thermal Imaging, when special lenses and processors are used to collect the light from the object and make image. Thermal imaging has two types i.e.
Un-Cooled
Cooled

3.1.3.1.3.1 Un-Cooled
This system operates at the room temperature and start working immediately with out any delay. The entire infrared component are assembled in a container or box to operate at room temperature. This system is quite silent having no moving parts. The sensitivity of this system is normal. [26]

3.1.3.1.3.2 Cooled
This system is quite expensive and is very rare to use. The operation of this system carried out below zero degree centigrade or 32F. In this system all the components are sealed in cooled chamber whose temperature is maintain below 32F. Due to special characteristic this system is named as “Cryogenically-cooled systems” this system has a long rang to view the image from a distance of 300 meters. Through this system at a good distance it is easy to trace a person holding a gun in his hand at a distance of 300 meters.

Use of this technology in CCTV camera added a great feature for detecting people and working in darkness. [26]

              CHAPTER - 4

                                                                                CCTV Next Generation Equipment
                                              Introduction of Radar Technology in CCTV Technology

4.1 Radar Technology
Use of radar technology with CCTV start late 1971 when first time radar and CCTV cameras are used for flight control to check the weather conditions and air traffic. As it was the time when technology was not so updated so both radar & CCTV were controlled and operated separately by different operators.[27]
A lot of improvement are seen in last few years and both CCTV & radar technologies start using by mixing each other. With the new software applications and most modern radar technologies added new features in security and surveillances. Now radars are used to detect the object in predefined areas and CCTV cameras take the image instantly. This radar system is effective above the water surface as they have the capability to detect the object over the water level. There are various types of radars and CCTV equipment available according to the requirement of the places. Like

Most of the radar detection system are expensive and are used in mostly sensitive places where high security and surveillance is required. Most of the site which are covered by radar system surveillance are,
Government establishments,
Military bases,
Embassies,
Airports,
Ports,
Large industrial sites, and
Other high value installations
The normal range of working a radar system is from 10 meter to 1600 meters in diameter. The maximum long range radars are also available which can cover the area of 5000 meters in diameter. Most of the security systems which are equipped with most modern radars technologies are fully automatic, which are automatically triggered and view the object with out any user interaction. The radar remains in operation round the clock all over the years in all weather conditions normally refresh rate is after every one second. These are the key features of radars equipped security surveillance system in modern age.
[28][29][30][31]

4.2: Key features of Radar equipped CCTV System
• This system enhance the security surveillance
• This system reduced the cost of operation with better security
• It is very difficult to evade this system
• It is very much effective in all weather conditions
• Provide best quality surveillance both day and night
• It can detect simultaneously various incidence in various directions
• Provide continuous tracking of foreign object in the alarm zone.
• Can define various alarm zone in different directions
• Provide continuous detection with refresh rate in every one second
• With various supportive applications, overlaid all detection data on to a site map
• With other supportive software applications activate alarm and other security equipment
• Identify the object to eliminate alarm to reduce efforts
• With additional software applications can provide continuous direction to follow the moving object
• Have the capacity to detect motion, walking, crawling and crouching
• In different software applications can define priorities like high and low risk areas
• Can calculate the velocity, position, location and heading of the object under surveillance
• Depending upon the software applications radars system provide both auto and manual operation.
[28][29][31][32]

4.3 ANPR
Automatic number plate reader is an other added feature in CCTV technology with the help of radars most modern technology. This technology is successfully used in restricted area where access of common public is restricted. This helps in automatic operation of various activities like automatic allow access in parking places for the known personals and automated door opening etc.

4.4: Allocation of area to monitor

With the help of software applications it is possible in this system to define the area to monitor and to allocate positions where the system remain effective as shown in this figure-33 with blue line marked.

 All these features make this system most effective to monitor sites more securely.

Reference

Proceed to Next Chapter