Posts Tagged ‘ security camera’



Surveillance Camera Lens

Written By:
Monday, July 11th, 2011

Surveillance camera lens are slowly beginning to evolve with the technology that supports them.  Before the digital age, a good majority of the surveillance cameras required that a lens be purchased for each camera.  Presently, some cameras still work that way, but the vast majority has the lens built right into the camera.  These lenses are often referred to as “board lenses.”

There are three major types of digital video camera based on their shape, the box type, the bullet type, and the dome type.  Basically the bullet and dome type cameras come with a lens already built into the unit.  This is often referred to as a board lens.  The box camera however, almost always requires the purchase of a lens.

As far as the lenses go, there are two different types of surveillance camera lenses, fixed and varifocal.  Fixed lenses do exactly what their name implies; they stay fixed in a certain immobile position.  Varifocal lenses have the ability to change their focal length either manually or remotely depending on the lens.

This means that for fixed lenses, the size of the field of view never changes; the lens can’t alter its own focal length so the width of the capture shot never changes.  This is great for use where there is no need to mess with changing the focal length regularly such as monitoring a parking lot, an entrance or exit, and other uses where zooming in on a subject or object is really not required and the camera will not be moved around a lot.

Varifocal lenses on the other hand, can move in and out changing the size of their focal length.  This is particularly handy when it is necessary to change the camera’s field of view to accommodate moving objects, tight shots, etc.  The focal length of a varifocal surveillance camera lens is normally expressed in millimeters (mm).  For example a fixed camera lens with a focal length of 3.0 mm will produce a fairly wide angle shot, whereas a focal length of 15.5mm will produce a narrow angle shot.

The nice thing about a varifocal lens is, depending on how it is made, you can get a focal length as small as possible and any focal length in between its maximum focal length.  It’s important to note that some of these varifocal lenses must be moved manually (by hand) while some our connected to a motor that drives the lens and is controlled remotely.

As long as we are on the topic of surveillance camera lenses, we’ll also mention a few of the characteristics of lenses that you probably should be aware of in addition to just focal length.  Four other points come to mind:  1. Depth of field; 2. F stop; 3. CS or C mount; and 4. Manual or Auto Iris.

Depth of Field

The depth of field is the distance from the camera to the object at which remains in focus.   Generally, the higher the F stop and tighter the Iris positions, the more objects that will be in focus.  In other words, a large Depth of Field means almost all objects in the Field of View can be in focus.  On the other hand, a small Depth of Field will only allow a small section of the Field of View in focus.

F Stop

The F stop is the foacl length divided by the effective aperture diameter.  In much simpler terms, the F Stop is an indication of the speed of the lens.  Since light must pass through the lens to the sensor, the F Stop gives us an idea of how much light it will absorb during the process.  A low F Stop lens is very efficient whereas a high F stop lens will require a lot of light.

CS or C mount

There are two standard surveillance camera lens mounts the “CS” and the “C.”  The difference between the C and CS is found in the distance between the lens and the CCD (Charged Coupled Device) or CMOS (Complementary Metal Oxide Semiconductor).  The C mount distance is 17.5mm while the CS mount is 12.5mm.

Iris

The iris works with the surveillance camera lens to control the amount of light entering the camera via the sensor.  For cameras mounted in positions that have changing light sources, it is a good idea to use a lens with an automatic iris.  For cameras used inside or in environments where the light conditions seldom ever change, manual irises are sufficient.

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Closed Circuit Security Camera

Written By:
Thursday, July 7th, 2011

The closed circuit security camera has been used for decades. But when the digital world began to affect the digital video security and surveillance world, it opened up numerous new features never available before that made this type of system versatile, powerful, and simple and easy to use.

In addition, digital cameras became lighter, circuitry came on very small Integrated Circuit Chips (IC chips), and all of these things contributed to driving prices down so that systems were much more affordable for individuals and not just big corporations or the incredibly wealthy.

Closed circuit security camera systems also known as Closed Circuit TeleVision or CCTV have evolved over the years and have come a long way technologically speaking. Older analog system cameras were pretty large and bulky, but today’s cameras are so small they can be hidden in the head of a Phillips screw!

Let take a look at the evolution of closed circuit security cameras and some of the features and options they offer today.

The original closed circuit security cameras were direct spin-offs from the television studio camera.   In the studio, the camera captured a video image, processed it somewhat, and passed it along to the editing room where any necessary changes could be made or added.  The signal was then sent through amplifiers that increased the signal’s power tremendously and sent it through a huge outdoor antenna.

Once the signal made it to the antenna it was “broadcasted” as far as the strength of the signal could go.  Anyone with a receiver, in this case a television, could “pick-up” these video transmissions and watch was being recorded.  Since the signal was just emitted in any direction and to any person wishing to view or hear it, the system was referred to as an open broadcast system (those of us that didn’t care to get too technical just called it “TV”).

CCTV or closed circuit security cameras worked on the same premise.  A video camera would capture a video image and then send it along a video transmission cable.  However, this is where the similarity ends because CCTV typically did not “broadcast” their video using an antenna.

Instead, cabling was used and was where the video image signal remained.   In order to see the video that was being captured an individual or video recorder would have to be connected to that cable.  Since all the components of the system were connected in one way or another, usually via the video transmission cable, this was referred to as a “closed circuit” hence the name “Closed Circuit TeleVision” or “CCTV” or specifically in the security industry, closed circuit security camera.

Granted, there are wireless cameras that have their own transmitter and antenna built right into the camera, but these cameras are on a special frequency and cannot be picked up with an ordinary TV.  So in essence, even though we still may broadcast security camera signals, these signals are only meant for the people that are designated to use the system.  Therefore we can “stretch” the meaning of the phrase “Closed Circuit Security Camera” to include even these cameras, since their transmitters and receivers still maintain a somewhat “closed circuit.”

In addition to wireless technology, here are just a few of the features available today with close circuit security camera:

  • - Night time Infrared technology.  The sensor chip in the camera is inherently sensitive to near infrared radiation as well as visible light.  These cameras can be used in conjunction with InfraRed Light Emitting Diodes or IR LEDs.  The human eye cannot see the IR LED light source, but the camera can.
  • - Pan-Tilt-Zoom or PTZ cameras.  These cameras can move horizontally or vertically and also zoom in on objects.
  • - Hidden or disguised cameras.   We sell a product (our product# HC-SCREW-W) as small as a Phillips head screw that contains a camera.
  • - IP ready (Internet Protocol) cameras contain their own web server technology and can be accessed by almost any computer or smartphone connected to the internet.
  • - Cameras with two-way audio.
  • - Object tracking or following.   Some PTZ cameras have the technology built right in to the camera to track or follow objects or people.

These are just a few of the things available with closed circuit security cameras.   For a more detailed look, check out our online catalog at http://www.securitycameraking.com.   You’ll be glad you did, we’ll guarantee it.

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Zoom CCTV

Written By:
Thursday, June 30th, 2011

One of the most popular digital video security system features is the zoom CCTV or Closed Circuit TeleVision.  There are many different types of Zoom CCTV cameras designed for a multitude of uses; be sure when shopping for one that you get the features you need.

What is a “zoom CCTV” anyway?   It’s a digital video security camera used in CCTV that can vary its lenses focal length enough to enlarge objects farther away from the camera and make them appear closer (enlarged) and with more detail.  These lenses are often referred to as varifocal.

Most box cameras that do not have built in lenses so they have the advantage of using Zoom CCTV lenses only.  These can be manual lenses where they are basically positioned through trial and error by hand or they can be remotely controlled as well.

There are also some cameras that do have on-board lenses that zoom only and these are often found among the bullet type and dome type cameras.  When we say “Zoom” only, we are referring to just the zoom function, as compared to a Pan-Tilt-Zoom or PTZ camera which has additional features including the ability to move horizontally or vertically.

Security Camera King has a wide selection of digital video cameras including cameras that can zoom.  Examples of varifocal lens “zoomable” bullet cameras that they offer include:

Security Camera King also has plenty of dome cameras with zoom capability.  General these lenses are “fixed” to the camera and cannot be changed.  This type of lens is often called a “board lens.”  They may also offer digital zoom as well.  Here’s a partial list of their Indoor Dome Cameras:

Security Camera King has plenty of outdoor zoom CCTV cameras also.  Once again, here is a partial list of their “Vandal Resistant” dome cameras that have zoom capability:

We’ll save listing the PTZ cameras when we write about them but of course, if it says it’s a PTZ camera, than it must have a zoom lens.

If you have any additional questions about zoom cameras and whether your situation calls for one or not, please contact one of security experts.   You may contact them via on-line “Live Chat” or by telephone at 866-573-8878.

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Multichannel Security Camera

Written By:
Monday, June 6th, 2011

A multichannel security camera usually refers to a wireless security camera that has more than one frequency that it can transmit its video (and audio for some) data over to a corresponding receiver.  The multichannel aspect is important to prevent cross talk, interference, or other reception problems.

Let’s begin our discussion with multichannel security cameras by reviewing how a “wired” digital video security system works.

The digital video camera is responsible for “capturing” the video image.  It does this by using one of two different photosensitive sensors.  One is called a Charged Coupled Device or CCD and the other is called a Complementary Metal Oxide Semiconductor or CMOS.  Although they both work a little differently, they both produce the same end result; data that can be used to construct a digital video image.

Generally the CCD or CMOS sensor is only 1/4 to 1/3″ square.  When light focused from the lens strikes the surface of the sensor, it emits a small electrical charge that can be measured.  This is used to construct the digital video image, but first the data must pass through a specialized Integrated Circuit or IC chip called an analog-to-digital converter.  The data also passes through another IC chip called a Digital Signal Processor or DSP which refines and fortifies the quality of the image

After passing through these components, the digital video data is now ready to be sent to the Digital Video Recorder or DVR.  The signal is sent along a cable or wire; many different types may be used but the most common is RG59 coaxial cable.  Using the proper adaptors CAT5 cable is also used.  The key here is that the video transmission must be “shipped” over a cable from the camera to the DVR.

Once the data reaches the DVR additional DSP chips compile the data and create a digital video file which can be stored for later use or viewed in real time (live).  The DVR uses something called a CODEC which stands for COmpression/DECompression utility.  The CODEC shrinks the size of the file incredibly while maintaining a high degree of quality.  The CODEC also prepares the file for streaming over the Internet if this is an option.

A wireless digital video security system basically works the same way.  The difference is the multichannel security camera contains its own transmitter circuitry and antenna.  It uses radio waves instead of RG59 or other cable to send the video signal from the camera to the DVR; most of the time this done using a corresponding receiver unit that is plugged into the video input of the DVR.

This is analogous to a land line wireless home phone.  The hand set has its own transmitter/antenna and it sends and receives signals to the base unit (receiver).  However, because land line based wireless home phones are so popular, it could be very easy for someone in the surrounding neighborhood to be operating on the same frequency as your phone.  This can happen with digital video transmissions as well.

Therefore these cameras are equipped with a selector that can be moved to choose a variety of different radio frequencies, or in this case, “channels.”  This can be a confusing term for the novice digital video security enthusiast because the word “channel” is also used to mean number of cameras or other devices.

So a multichannel security camera is a digital video security camera that has more than one radio frequency that it can transmit over.  Generally, the more channels available the better.  For example if you have an 8 channel (camera) DVR the wireless cameras will need 8 separate radio frequencies (channels) to prevent interference.  Likewise, the receiver will require the same or you may be able to use one receiver per camera, which could get a bit tedious.

If this article has not shed some light on what a multichannel security camera is, please contact one of our security experts via 0n-line “Live Chat” or by telephone toll free at 866-573-8878 Monday through Friday from 9AM to 6 PM EST.  They will be happy to explain any additional information and help you with the design, installation, set up, and use of a Security Camera King multichannel security camera system.

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Security Camera Computer

Written By:
Tuesday, May 31st, 2011

The security camera computer of a digital video security and surveillance system is basically the “brain” of the system.  This is where the COmpression/DECompression or CODEC utility is normally used to shrink the size of the incredibly large digital video files made by the security camera.  The security camera computer is also the central controller for the entire digital video system, coordinating all the actions of the components in the system.

Another name that is more commonly used instead of security camera computer is Digital Video Recorder or DVR.  Although admittedly, there are some systems where the DVR is only a storage device and does not control the entire system.  Let’s start from the beginning to see just exactly what a security camera computer does.

An average digital video security surveillance system is a component system that consists of three major components (it may have more or less depending on the system).  The components are the digital video cameras, the DVR, and the monitor.  Note that the phrase “security camera computer” did not appear anywhere in the previous sentence, although the functions of a security camera computer are normally considered the tasks of the DVR.

The digital video security camera creates an electronic based video by converting the light images gathered by the lens and focused on a special sensor chip.   The sensor chip contains pixels that when struck by light emit an electronic pulse that can be measured, interpreted and used to create and electronic recreation of the field of view of the camera.

Interestingly, up to this point, everything has been in analog format.  The camera has a special processor called an analog-to-digital processor that converts the analog information into digital data.  Cameras normally contain another processor that helps to stabilize and improve the display of the digital video.  This processor is called a Digital Signal Processor or DSP.  Once the data has been processed by the camera it is sent to the security camera computer (or DVR).

There are basically three types of security camera computer.  The first we’ve already mentioned; it is the most popular type of security camera computer in use today and is called the DVR unit.  While it’s true the major function of the DVR is to process and store digital video files, it generally coordinates the activities of all the other components within the system.

For example, the DVR (or security camera computer) is either responsible for or performs the following actions for the digital video security system:

  • CODEC application – the security camera computer uses a CODEC utility to shrink the size of the digital video file while maintaining as much original detail and quality as possible.
  • Operation of special uses cameras – The Security camera computer may also be equipped to control special use cameras such as a Pan-Tilt-Zoom or PTZ camera.  It may include programming the automatically initiates the PTZ camera to “lock on” on track or follow a specific object (such as a car in a parking lot).
  • The security camera computer also coordinates activities within the DVR itself.  For example, many DVRs are capable of recording several cameras at once while simultaneously playing back previously recorded video.
  • The DVR may also contain the components required to access the Internet and make controlling the system form anywhere in the world that 3G or 4G smartphones can operate.

The second type of security camera computer is the Network Video Recorder or NVR.   The NVR typically doesn’t control as many accessory type functions as a DVR.  The NVRs role is to coordinate the use of single or multiple Internet Protocol (IP) ready cameras.  This could mean that a camera could be placed at one address and another in a totally different location (such as a different city) and by using the Internet is able to “network” these cameras as is they were one local system.

Finally, the third type of security camera computer is, of all things, a computer!  These systems usually have plug and play PCI cards that are installed on the computer.  The PCI card may perform a great many of the functions that are needed using the computer only for storage purposes on its own hard drive.  Nonetheless, this is a type of security camera computer.

As you can see, the security camera computer performs a great number of tasks in addition to storing the digital video files.  It truly is the “brain” of a digital video security system.

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