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CCTV Frequently Asked Questions

Frequently Asked Questions

  • What is a Security DVR?
    DVR stands for Digital Video Recorder. A Security DVR is capable of taking the video from digital or analog cameras and recording it into a digital format on a hard drive. It can record high quality video, maintenance free, for weeks or even months. An ideal replacement for time lapse VCRs.

  • What is a video capture card?
    A video capture card or DVR card is a graphic card inside the Security DVR system which captures the signal from the cameras and stores the video on the hard drive.

  • How many hours of video can the Security DVR store?
    The length of archive depends on number of cameras, frames per second (FPS) and amount of available hard disk space. Our preconfigured systems usually provide several weeks of archive on motion detect mode.

  • How does motion detection work? Through the camera or software?
    Motion detection works through the software in the DVR system by recording video when pixels in the image change. Most Security DVRs offer a sensitivity scale so the user can set the sensitivity of the motion detection.

  • Can I view live and recorded video locally?

  • Can I view live and recorded video remotely?
    Yes, most of our Security DVR systems are Internet enabled. You can view live and recorded video from anywhere through the Internet.

  • What kind of broadband do I need? How much bandwidth?
    Basic DSL or cable will suffice in most cases.

  • Can several users view one site at once?
    Most Internet-enabled Security DVR systems allow multiple users to view the same site simultaneously. However, as more people look at the same cameras/DVR at the same time, the bandwidth will be shared between them.

  • Can I record audio?
    Yes, if the Security DVR system comes with an audio option you can record audio. Most analog cameras do not come with built in audio, so you will probably need a separate audio kit.

  • Can I listen to live and recorded audio remotely?
    Yes, some of our Security DVR systems have that option. With an optional audio module, you can listen to live and recorded audio from anywhere through the Internet.

  • How many cameras do I need?
    This will depend on the size and layout of the area you wish to survey. On average, we recommend one camera per 1000 Sq. Ft.

  • Can I use my existing cameras?
    Yes, you can use your existing CCTV cameras. Simply plug them into the back of the Security DVR which replaces the VCR.

  • What camera lens size is the best for my application?
    Home CCTV System carries a large selection of security camera lenses, but the lens you will need depends on where you plan to use it. Review our Lens Selection Chart to determine the type of lens that is best suited to your needs.

  • What is an Auto-Iris Lens?
    An auto iris lens provides consistent video signal in areas where light levels vary.

  • What is Lux?
    Illumniation is measured in units called Lux. For more information, please refer to our LUX Explanation Page

  • Can I zoom in with a camera?
    Yes, but you need a special camera called a Pan-Tilt-Zoom or PTZ camera. Browse our selection of PTZ cameras and find the one that is right for you.

  • What type of Operating System (OS) does the Security DVR use?
    Most Standalone Security DVRs are Linux based.

  • What kind of cable should I use?
    Siamese cable, which is an RG59 coaxial cable and a pair of 18 gauge wire for in the same jacket to make installation easy. Check out our cables page and find the length you need.

  • What happens if there is power outage?
    Most Security DVRs will come back on as soon as power is restored. However, we suggest an uninterruptable power supply (UPS) which provides a short period of backup power and also serves as a surge protection device.

  • Can the Security DVR report an alarm?
    Yes, some Security DVRs have that option.

  • What is the Difference Between C & CS Mount lenses?
    The physical difference is that the back of a CS mount lens is 5mm closer to the chip than a C mount lens. You can always use a C mount lens on a CS mount camera by using a 5mm spacer ring (many cameras now have C/CS selectable adjustment screws or rings). You can never use a CS mount lens on an older style C mount camera. Cost wise the CS mount lens is much less expensive since it uses fewer glass elements. Quality of image is the same. C mounts are becoming less and less popular and are generally only used on the more telephoto focal lengths such as 25, 50 and 75mm, and bigger zooms.

  • What is relationship of the angle of view and lens size of the CCTV camera lens?
    This lens calculator displays the angle of view of common CCTV lenses. The calculator is compatible with all the standard CCD sizes, such as 1/4 inch, 1/3inch etc. These are the standard CCD sizes used in CCTV and security applications.

    CCD Size (Inch)








    Lens Size (mm)








    Angle of View(degrees)








  • Can I use any type of CCTV security camera outside?
    Not really. Some bullet cameras, Vandal proof Dome camera and most Infrared cameras are designed for outside use with waterproof cases, but if you need lenses of different focal lengths and especially if you need auto-iris lenses (which are best for outside because of varying light conditions) then mini-cams won't be satisfactory. Normally, box cameras are used outside but need to be mounted inside a special outside housing. These housings are rainproof and can also contain a heater unit for really cold climates and/or a fan for hot climates. Mini-dome CCTV security cameras, most Dome camera and some hidden camera meant for inside use only, should not be used outside.

  • What does an auto-iris lens do for me?
    Outdoor security cameras or cameras indoors facing a window or an outside door will have varying light conditions. CCTV display and recording systems are set to a certain level of image brightness and contrast. When light levels change in the images produced by the cameras, the displayed and recorded images will either be too bright and washed out or too dark and non-resolvable. The only way to solve this is to use an auto-iris lens. These lenses have an electric motor-driven iris which is opened or closed according to signals fed to it from the camera. Once set, a camera equipped with auto-iris drive will attempt to produce a video signal of constant brightness by opening or closing the auto-iris of the lens, as light levels change.

  • What is the vari-focal lens or zoom lens?
    A Vari-focal is a lens that is designed to meet the most challenging jobs by giving the installer the flexibility to adjust between different focal lengths using only one lens. When the situation calls for an odd focal length lens or you are not sure of the correct focal length required for the installation, using a Vari-focal lens is the perfect choice. How many times have you or your installer set-up a job just to be called back because the customer was not satisfied with the field of view of the picture? More than once, most likely. A simple adjustment to the zoom and focus on a Vari-focal lens is all that is needed to rectify the situation on the spot: a less costly and time-consuming prospect than having to order and install a different monofocal lens altogether.Surveillance effects are maximized since any desired angle of view can be obtained.

  • Why use a vari-focal lens?
    Surveillance effects are maximized since any desired angle of view can be obtained. There is no need to carry several different focal length lenses to an installation job. Once installed, even if the field of view requirements change, the system can be quickly adjusted by simply changing the focal length setting of the lens.

  • If I purchase fixed focal length lens or security cameras with fixed lens, can I exchange those if I don't like the field of view that I see?
    Yes you can, provided they are shipped back in the original packaging and are in "as new" condition. However, you will be liable for the shipping charges, both ways and this, combined with the hassle involved, usually makes it an unsatisfactory thing to do. Better, in the first instance, if you are unsure about the lens focal length required, to purchase cameras with vari-focal lenses. These are manually adjustable over a range of focal lengths, most commonly from 3.5 to 10.5mm, to give a wide range of field of view.

  • How far from the DVR can I place security cameras?
    Using RG59 Coaxial Cable, each CCTV security camera can be placed up to 600 feet from the computer and up to 1,000 feet with RG6 Coax. Even longer distances (>2,000 )can be achieved using Baluns and CAT5 cable

  • Can I use my old security cameras mixed with new ones?
    Yes, providing certain conditions are met. Even with the same color type, some older cameras and some newer cameras mixed together can cause problems because of very different image synchronizing systems. In this event, you can get interference between one camera image and another. Color cameras are more prone to this type of problem.

  • How many days/weeks of recording can I store?
    This depends on how big is your hard drive, how many cameras are you using and under what conditions are you recording (on motion, on alarm, continuously, etc.) and what type of compression you are using. Assuming that you are recording only when motion is present (the most common recording method today) using a 30fps board and assuming that you have 4 CCTV security cameras and that there is movement in the surveilled area for 16 hours a day, 5 days a week, and you are recording at 320x240 pixel resolution with MPEG4 compression, you could expect to use up about 20 to 25GB of disk space per week. So, a 40GB drive would hold about 2 weeks of recordings under those conditions.
    Of course, if you record at 640x480 pixel resolution, and/or you are using a 120fps or faster board, the disk space used will increase. Because of the way that MPEG4 compresses video, there is not a definite mathematical formula that can be applied to say exactly by how much the recordings would grow.
    Since hard drives are now relatively inexpensive, it pays to use as big a capacity drive as possible (and/or multiple drives) if you are concerned with storing many weeks of recordings before overwriting.

  • What happens when my hard disk is full?
    Normally the system will begin to overwrite the recorded image files, oldest first. You can choose for recording to cascade from one drive to another (i.e if the "C" drive is full, the system can begin to write on the "D" drive), if you have more than one hard drive.

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