CCTV Cameras

Q1. How does a CCTV Camera work?
A. Like a human eye, light enters through the pupil (camera lens) it hits the retina (image sensor) which processes the image into a signal. This signal is sent to the brain (DSP or chipset) where it is processed and adjusted depending on different light conditions.
Q2. What does TVL or Television Lines mean?
A. TVL is often misunderstood as the deciding factor on the quality of a camera. Unfortunately it’s not. TVL is the number of horizontal lines of an analog camera’s resolution. While TVL is one of the most important resolution measures in a video system, a much more important factor in CCTV terms is ensuring you have the correct lens type for your application.

Your camera’s lens is the defining factor in quality and cannot capture detail beyond its own capabilities. If you had both a 420TVL camera and a 700TVL camera which both had the same lens then the 700TVL camera wouldn’t be able to see much further than the 420TVL. You may have a slightly better picture due to the increase in resolution but if you can’t read a number plate at 20m using the 420TVL then the problem is the lens not the resolution.

Q3. Do I need a fixed lens or Varifocal?
A. A fixed lens camera is one that cannot be adjusted to zoom in and out and is normally used for indoors or monitoring closer areas. Fixed lens cameras are normally a cheaper choice and can save you some money if you don’t need to have a zoomed in view of an area.

A varifocal or vari lens camera has the ability to optically zoom in on an area. The variable focal length can be used to change from a wide angle view covering a large area to a narrow focal view to centre on a particular area at long or short range. This is a popular choice as it is versatile and can easily be adjusted to suit your needs.

Q4. How does the lens focal length affect the image?
A. Often misunderstood as the diameter of the lens; this is the focal length of your lens (usually measured in mm). In smaller focal length lenses the field of view is wider, allowing in more light. As the focal length increases less light can get through the lens which result in a narrower telephoto field of view and the camera detects a more detail from its target area. This works in a similar way to using a pair of binoculars.

Essentially this factor determines how much you can optically zoom in and out on a varifocal camera.

Q5. What are infra-red LEDs
A. Infra-red LEDs are used to illuminate a dark area a dark area for viewing. As light levels fall, the infra-red lights switch on automatically changing the image to black and white. The majority of cameras on the market now feature infra-red lighting, and with more LEDs you can usually expect an increase in illumination range.
Q6. Will bright daylight damage an infra-red camera’s LEDs?
A. No. Our infrared security cameras (which use LEDs) are designed for both low light and lighted use, so daylight will not damage them. The infrared LEDs stay off during the day while it is light out and then turn on at night in the dark when they sense that the light is low enough. Outdoor bright light use in the day will not damage them in any way.
Q7. What are the different types of CCTV Camera available?
A. There are numerous types of camera and we will explain them as follows:


Dome cameras are generally the most popular indoor choice of cameras thanks to their compact size options, motorised 360 degree rotation options as well as being sturdy. Generally, there are three main types of dome camera available.

Internal Dome cameras

Internal dome cameras feature an additional ‘dome’ housing which is an advantage as you can’t knock the lens. This additional house can also come in a ‘blacked out’ form which can be useful for hiding which direction your camera is pointing.

Eyeball or “Eye” Dome cameras

Eye dome cameras are usually a sturdier choice with many featuring armoured housing which allows them to be vandal resistant. They also have superior infra red illumination.

PTZ/Speed Dome camera

These cameras can come in both open and internal styles, and feature electronic motors which can be controlled to look around or even zoom in and out using a controller. They tend to be reserved for use only in large scale developments.


Featuring a bullet-like shape, these cameras are the classic choice. All of our bullet cameras feature infra red illumination. They are suitable for indoor and outdoor use and can range from small, plastic housing up to large heavy duty armour-cased cameras.


Similar in appearance to bullet cameras, these cameras generally feature a square casing, hence the name.


These cameras are small, easily hidden or disguised cameras, which might be a better, more discrete choice for your home or business. Despite their small size, our covert cameras are capable of a professional quality video feed.

Q8. How long will my system record for?
A. All data is recorded to a built in hard drive on the DVR (Digital Video Recorder), the bigger the hard drive, the longer your images will be saved. For example, a 250GB hard drive should record four cameras (depending on frame rates) for just over a week. Therefore, it will record one camera for over four weeks.
Q9. What happens when my DVR is full?
A. Nothing. Your Digital Video Recorder will record over old images when the hard drive is full. So if you have capacity to record for 30 days, on day 31, day one recordings will be deleted to make room on the hard drive for day 31 recordings.
Q10. Can I make my DVR record for longer?
A. Yes, you can switch on motion detection so that your Digital Video Recorder records only when motion is detected.

In a normal domestic situation, using motion detection could add weeks to your storage time, but there’s a price to pay. You’ll need to have the sensitivity on your motion detection quite high to ensure that you don’t miss anything. Increasing the sensitivity will mean that you will also record rain and possibly wind, especially if your cameras point to anything that moves in the wind.

Q11. What is remote viewing of CCTV?
A. Remote viewing allows you to view your CCTV cameras from anywhere in the world via your home broadband internet connection. You can view the images 24 hours a day, 7 days a week through your PC, laptop, tablet or smart phone.
Q12. How does remote viewing of CCTV work?
A. In simple terms, you have the sender (your house) and the receiver (your PC/laptop/phone etc).

SENDER: The sender comprises of one of more cameras connected to a video streamer. The video streamer literally streams the video signals over either a local network or the internet. In order for the receiver to be able to find the sender, it is allocated a unique IP address or a URL (web address).

RECEIVER: The receiver comprises either a PC/laptop (connected to the internet) or a tablet/smart phone with an application installed. The user enters the allocated IP or URL address and if required, a user name and password.

Q13. Do you charge extra for remote viewing?
No. When we install your CCTV cameras, we network your system which will enable you to remotely view it and this is included within our supply & installation charge. There are no additional subscription charges to be paid.
Q14. Can this be used with my current Broadband connection?
A. This system will normally work with any type of broadband connection. If you have a fixed IP address and a compatible router then the system should work with little fuss.
Q15. How many CCTV Cameras will I need to have installed?
A. This will depend on the size and layout of the area you wish to monitor. We always carry out a no obligation survey and our service engineer will be able to advise what is best for your home or business premises.
Q16. Can having CCTV Cameras installed reduce my home insurance premiums?
A. Yes reduced insurance premiums can be a benefit of having CCTV cameras installed as most insurance companies will recognise the additional security benefits of having a CCTV camera system installed. However, please be aware that i-Spy CCTV & Security cannot guarantee that a reduction in premium will be obtained and therefore, it is your responsibility to liaise with your insurance company about this.

Visonic Intruder Alarms

Q1. What is the output of the wall-mounted siren in decibels?
A. The technical specification is 110 decibels.
Q2. How long will the siren sound for when the alarm is triggered?
A. The siren will sound when triggered for a pre-selected time of up to 15minutes, chosen by you. The system will automatically be re-armed again after this time period has elapsed.
Q3. Can I use more than one external siren on my Control-panel alarm?
A. Yes ~ it is possible to have two sirens. Separate sirens can be purchased by calling us on 0845 459 9626 or from our installers at the time of installation and “dummy” boxes are also available.
Q4. How is the external siren powered?
A. The siren uses a Lithium 3.6v Bell Box Battery.
Q5. How and when will I need to change the batteries in the siren?
A. Siren batteries should be refreshed every 3-4 years.
Q6. How many telephone numbers can be stored on the Visonic PowerMax control panel?
A. A maximum of four telephone numbers can be stored.
Q7. I have a shed / garage, will I be able to use a detector in this location?
A. There will not be a problem in using a detector in this location provided it’s not too far away from the control panel.
Q8. I have pets at home. Is it likely they will trigger my alarm and if so, how can I overcome this problem?
A. You can use pet friendly sensors. Alternatively, magnetic door contacts or curtain sensors could be used in place of a PIR for this purpose.
Q9. Why does the alarm not trigger when I walk in front of a PIR?
A. All Visonic PIR’s have a built-in 60 second sleep timer, to prolong the battery life. Arm your system before vacating all areas occupied by PIR detectors for a maximum period of 60 seconds, before re-entering the area and retesting. Please bear in mind that a faster reaction is obtained when movement is detected by walking across the field of view of a PIR lens, rather than simply standing in front of it.
Q10. What is the maximum movement detection range of a Visonic PIR?
A. The Visonic PIR’s will respond to movement of up to 15 metres away.
Q11. Should the red light flash on my PIR?
A. The red PIR lights will not always flash in order to conserve the battery life. If you are in any doubt of the operation of a PIR, vacate the area for up to 60 seconds, and test using the ‘walk test’ facility.
Q12. Can I test my new alarm without annoying my neighbours?
A. The Visonic PowerMax and all other Visonic control-panel based systems have a useful ‘walk test’ feature. This allows radio range testing of the various devices, without having to audibly test your alarm so as not to cause a nuisance to your neighbours.
Q13. Are all Visonic alarms completely wire-free?
A. All of the detectors are completely wire-free, for the control panel mains, wiring is required and a telephone line is also needed.
Q14. I wish to expand my existing Visonic alarm. How many detectors can I use in total, and where can I purchase additional accessories from?
A. Visonic alarm systems will accommodate a maximum of 28 devices. Here at i-Spy CCTV & Security we sale a range of additional accessories so you only need to contact us on 0845 459 9626 and we’ll be happy to help.
Q15. How often will I have to change the batteries in my alarm system?
A. Batteries should be replaced every 2-3 years. Each detector, siren and control panel will inform you when this is required.
Q16. I have a large household with many family members, young and old, entering and exiting the property at varying times of day. How can I overcome this?
A. It is recommended that several key fobs or tags are programmed in. The individual members of the household can carry their own key fob/tag around, allowing simple arming and disarming of the system as desired.

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