CCTV FAQs

The ability to film in low light conditions or even complete darkness is essential for many CCTV applications. Part of that ability is down to using the right electronics which are sensitive enough to work in low light, the other tool used is infrared or IR lighting. We have a guide to infrared in our camera buying guide.

Infrared light isn't visible to the human eye but CCTV cameras switch to black and white as light levels fall and can film the IR light spectrum. This means that to the camera it's like shining a torch. IR has to bounce off something but providing there is a hard surface to reflect the infrared your camera is able to see in the dark.

Previously cameras had separate infrared light lamps bolted onto the side of their housings. It made the whole unit very large and industrial looking. In more recent times cameras have been designed with IR lighting built into them. This greatly reduces their overall size and visual impact. It also reduces cost when compared to modular cameras using separate lighting units.

Many people selling CCTV cameras describe them in terms of the infrared range. Do not confuse this with the optical range of the camera or the distance at which a camera can record detail. That is determined by the lens. Wider angle lenses will have a shorter optical range, more telephoto lenses a longer range. The IR range is a largely immaterial figure, often made up and is supposed to represent the distance at which the camera's infrared can be detected. In reality, the ability of a camera is a combination of the lens, how powerful the IR is and how sensitive the electronics are.

Something you might see mentioned is an IR cut filter. This is a mechanical filter that moves in front of the camera lens during the daytime. The filter is designed to improve colour rendition during daylight filming. Electronic adjustments can also be made to the camera to improve colour representation.

We get a number of calls from people experiencing problems with their CCTV cameras at night. They install a CCTV system during the day then at night find they have issues. We have created this page to cover some of the most common symptoms and causes.

No image at night

The most extreme problem is seeing nothing at all on the screen. Check all the same things you would look at during the day. Make sure the camera has power, ensure all the connections are secure and that the infrared is illuminating (this will mean power is getting through to the camera). If that is all in order then stand in front of the camera quite close to it. Infrared needs to bounce off a surface back into the camera. If you just point the camera into space it won't see anything.

If you have bought a camera with a long-range, 20 or 30 metres plus from someone and you are expecting it to work at that distance don't rely on quoted specs. IR range is pretty much made up and shouldn't be used as a guide to effective range. You could be trying to film too far away. Stand closer to the camera and see if you can see an image. Failing that you may be suffering a voltage drop.

Voltage drop

One of the most common problems experienced is voltage drop. When the IR illuminates the power requirement of the camera increases, if the cable run is too long or there isn't enough copper you will experience a voltage drop. This could cause the camera to stop working altogether. It could also cause the camera to cycle on and off. The IR illuminates which causes the camera to switch off. The camera re-starts and works until the IR switches on again. You may also see image deterioration when a voltage drop occurs. If you are using CAT5 cable to join the cameras to the DVR and power supply make sure you are using a pure copper cable rather than CCA or copper-clad aluminium. Wire the cameras as per our guide to using CAT5 cable in CCTV. In particular, make sure you use 3 pairs of wire for the 12 volt supply.

A white screen or white areas on the screen

This is another common issue. If you see a white screen at night or a white haze then the most likely cause is infrared light reflecting back into the camera lens. The wider the angle of view the more chance there is of this happening. Have you got the camera's sun visor too far forward? We suggest having the rear of the visor in line with the back of the camera body. Is there something just out of shot but in front of the camera which can reflect IR back into the camera, guttering and soffits are common culprits? On vandal dome cameras check to make sure any sealing rings which fit between the lens and the inside of the clear plastic cover are securely in place.

Whilst you can't see the infrared light in the camera it is extremely bright and any surface close to the front of the camera can reflect the light back into the lens. Even if the surface is out of screenshot it can still reflect the IR. If you can't move the camera try zooming it in more so you narrow the field of view. Light pollution from other sources can also cause white areas to appear on the screen. Vandal dome cameras are particularly prone to corruption from external light sources.

A camera mounted inside a window produces a white image at night

Well, it will do. The glass is a reflective surface and is right in front of the camera. The infrared will bounce off the glass straight into the lens causing the camera to dazzle itself. It's a bit like taking a flash photograph in front of a window at night.

General image deterioration at night

When the infrared switches on the camera draw more current. If your power supply is not powerful enough this extra current draw could cause problems. Also, make sure you have not exceeded the recommended cable run length and that the cable is substantial enough. Voltage drops along the length of the cable and the thinner the cross-sectional area of the cable the more this happens.

General haziness of the image at night with some movement on the screen

Check the camera for spider webs. During the day you don't notice spider webs. The camera focuses beyond the web and it appears invisible. At night the infrared bounces off the web and it shows very clearly. We do sell a spider spray to help reduce this problem.

Moving spots in front of the camera at night

This is similar to the spider's web problem but instead of a web, the light is reflecting off dust or particles in the air. This is particularly noticeable in fog where the water droplets suspended in the air reflect the infrared. Warm currents in the air can cause particles to rise as well as fall.

This isn't an exhaustive list of problems encountered at night but it covers the most common ones.

Motion detected recording is a feature on all our DVR recorders. The DVR monitors camera images and decides when it thinks there is movement. To do this the DVR looks at individual image frames and compares them to the previous one. If it sees differences then motion is assumed to have taken place. It is the DVR, not the cameras which are looking for movement.

A DVR isn't as intelligent as you or I and can't differentiate between background movement, changes in light and someone coming to break into your property. To help minimise false triggers it is possible to limit where on the screen the DVR looks for movement and limit this to a small area or a number of areas. You don't have to use the full screen. You can set the trigger area using the setup menu on the DVR, you can also set the trigger area remotely if the DVR is connected to your local network / the internet.

Some people only record footage when motion is detected in an attempt to extend the time footage is stored. We are not big fans of doing this. We would rather see motion triggering being used to create bookmarks within 24/7 recording rather than the sole means of capturing footage. Use it to identify which sections might be important but still have constant footage on either side of the trigger.

Systems that use motion triggering as the sole method of recording are usually trying to compensate for too little memory. We recommend allowing 250GB of hard drive space per camera on SD systems, and 500GB per camera on HD systems. See our guide to hard drives.

A CCTV system will be based around a DVR or digital video recorder. CCTV cameras are connected to the DVR using cables and there will be some ancillary items such as a power supply for the cameras.

DVR or digital video recorder
The DVR is the heart of the CCTV system. It takes all the camera inputs, arranges them on screen for live viewing and also stores footage onto a hard drive for viewing at a later date. Our DVRs record all the cameras regardless of what you are viewing live on your monitor. It is possible to view 1 camera at a time or several cameras in various combinations depending on how many channels the DVR supports. We sell 4, 8 and 16 channel DVRs which are suitable for 4, 8 or 16 cameras respectively. They can be combined, so 2 16 channel DVRs could host a 32 camera CCTV system.

Our DVR recorders also support remote access over the internet. You need to connect the DVR to your internet router. This can be done either with a cable, a power bridge adapter that uses your electrical wiring or a wireless network point. Then wherever you are in the world you can view live footage from your cameras, see previously recorded footage, make backups of important events and even make settings changes to the DVR.

The cameras
CCTV cameras are the most important thing to get right and we have devoted quite a bit of space on our website to help you make the right choice. We are always glad to offer help and advice if you are planning a CCTV system so pick up the phone and give us a call. We can have a look at your property using aerial images whilst talking through your specific requirements and select which cameras will best suit your requirements.

Cables
The cable from the DVR to the camera does 2 jobs. It transfers video from the camera back to the DVR and it supplies 12-volt power to the camera. Video connection is via a BNC connector. If you are using CAT5 cable then the BNC connector will be part of the video balun. 12-volt power connections are 5.5mm jack plugs. At the camera end, there is a DC plug, and at the DVR end a DC socket into which the 12-volt power supply for the camera connects. For this reason, you would normally locate the camera power supply next to the DVR unit. The DVR will be supplied with its own 12-volt power supply.

Like everything in life CCTV is available at a range of different prices points and quality levels. You can fly on a plane for £500 in the economy or you can pay £5,000 to fly on the same plane in a first-class suite.

The problem with CCTV is a lack of regulation and failure to understand the basic principles means people often sell systems that won't do what they claim. They sell you a first-class suite but you board the plane to find yourself squeezed into a small economy seat. Actually, it's worse than that, they sell you a first-class suite to New York but you get to sit on an orange crate whilst the plane flys to Luton.

People selling CCTV tell lies
We set up CCTV42 for frustrated customers. We did our homework, looked at the specifications, listened to the sales patter and were very disappointed with what turned up. When you know what you are looking at the claims made by people selling CCTV are appalling. It isn't just the odd seller on eBay, it's rife across the industry. Big national retailers are misleading buyers in an attempt to get their money.

When you see a camera with a claimed range of 25 metres you assume it's capable of filming something 25 metres away. You might allow a bit of artistic licence and work on 20 metres to be safe but the reality is it might only have an optical range of 3 or 4 metres.

The specifications retailers use are often not important
Sticking with CCTV cameras as our example retailers often use TVL (television lines) as a determining factor in how good or bad their products are. The number of TV lines has little to do with the quality of a camera, that is more to do with the lens fitted and its optical range. Even if TVL was important retailers rarely quoted TVL correctly, they advertise 560TVL cameras as 1000 TVL cameras because they don't understand how TVL is calculated.

Compare eggs with eggs
This is easier said than done. There comes a point where it becomes almost impossible to distinguish truth from reality, particularly when many of the retailers are well-respected household names. Whether deliberately or through a lack of technical understanding they are making claims for their products that simply aren't true.

Advice and support
We don't just sell boxes. We listen to customers' needs, advise them as to the most appropriate equipment and then support them once their purchase arrives. That advice and support are vital but usually lacking at the cheaper end of the market. CCTV isn't difficult once you understand a few basic rules but most people struggle because they are misled by false claims. Only a tiny proportion of CCTV fitted actually does what it should. We want to ensure you are one of those small minority who owns effective CCTV solutions.

Please don't hesitate to get in touch with us if you are planning a CCTV system. Call during office hours and we can talk through your requirements whilst looking at your site or property using aerial images. From that, we will be able to tell you

We have recently added our camera buying guide which has a section specifically about CCTV camera range. It's worth spending some time reading through the guides as they will answer most or all of the questions you might have. If you need help regarding a specific project please don't hesitate to get in touch, we are always happy to provide advice free of charge and without obligation.

TVL and IR range
People selling CCTV are often very misleading when it comes to CCTV camera range. They normally quote two figures, the number of TVL and the IR range. This might be called the nighttime range. IR range is a largely made-up number based on how far away from the camera Infrared light can be detected. It has nothing at all to do with the effective range at which detail can be filmed.

Optical range
The distance at which detail can be captured using a camera is its optical range. Unfortunately, no one ever quotes it, they only quote the IR range. The optical range has nothing to do with how many TVL the camera has or how bright the IR is, it all depends on what lens is fitted.

A DVR stores images as tiny dots or pixels. With D1 resolution you get around 400,000 pixels per image frame. With a wide-angle lens, the pixels spread apart very quickly as you move away from the camera and fewer pixels mean less detail is captured. Conversely, a telephoto lens concentrates the pixels and captures more detail further from the camera. Camera lenses are measured in mm, the smaller the number the wider the angle of view. 2.8mm or 3.6mm would be considered wide-angle.

How do you quantify detail?
There is no definitive answer, it will depend on your specific needs. With some systems the ability to identify people will determine detail, on other systems, it might be the ability to read a vehicle registration plate. When we quote optical ranges we base them around how far from the camera a vehicle registration plate can be read.

We have a page that shows HD1080P CCTV camera images with different lens options

Varifocal cameras
A varifocal camera allows you to manually zoom in or out during installation. This means one camera is able to perform different jobs. It can be set to wide-angle or telephoto. This means you don't have to worry as much when buying the camera, you can balance the angle of view and detail captured once it is fitted. You just need to make sure you have the correct lens range, we can help you decide.

With fixed lens cameras, you only get one chance, if it's the wrong angle you have to replace the camera. For that reason, we would always advise buying varifocal rather than fixed lens cameras.

The low lux figure is supposed to represent the sensitivity of camera electronics and its ability to film in low light. It will also influence how well the camera performs when using its built-in infrared lighting. Much of a CCTV camera's life is spent filming in low light at night so low light performance is quite important. We have recently added a CCTV camera buying guide which includes a section on Low Lux levels.

How are low lux figures measured?
There are no ISO standards for measuring CCTV camera lux levels so you need to be wary of any quoted figures. Something called an IRE (institute of radio engineers) number is used. This is a measurement of brightness and contrast scored as a percentage. 100 IRE is a perfect image. White is white, black is black and there is a clear greyscale in between. 50 IRE means white is light grey but there is still a greyscale down to black. A 50 IRE image has 50% of its contrast and brightness and would be suitable for security purposes. Eventually, with lower IRE numbers you can only make out white from black with no greyscale.

The minimum IRE number you are prepared to accept makes a big difference to the minimum Lux figure. You also need to decide how wide-angle and large the lens is going to be. Large wide-angle lenses let lots of light in so if they are used the low lux figure will be artificially improved.

Finally, the shutter speed needs to be set. A long electronic shutter speed allows the camera to see in low light but any movement will be blurred so it wouldn't be suitable for security use. Because there are no ISO or industry-standard parameters quoted low Lux figures should be largely ignored.

TVL and low lux
Many people think TVL is the holy grail of CCTV cameras - it isn't as can be seen from our CCTV buying guide, so retailers use cheap electronics with a high number of TV lines. These tend to be less sensitive than lower TVL electronics so the low light performance is poor. High TVL and good low light performance are harder to achieve and more expensive. For this reason, be careful to avoid cheap high TVL cameras.

Zero lux cameras
This is a bit of a con. People selling cameras with a minimum Lux of 0 are just saying that the camera has built-in infrared illumination. All cameras with their own light source are designed to work in total darkness. What you actually want to know is how sensitive the base electronics are and so how well the camera will be able to use that infrared lighting.

Signs of good electronics
A good CCTV camera should be able to see much better than the human eye in low light conditions. As day becomes night you should look at your monitor, do you think it is still daylight? then walk outside and be surprised at how dark it is. When looking at different electronics we use our eyes. We don't rely on theoretical numbers, we look at practical results out in the field.

Yes We are a real company and not a one man band.

We give 2 years

Yes We only install the best which is Hikvision & Dahua cameras and not just any lower quality cameras.

Yes We are fully insured with public and employee insurances.

Our engineers have trained at Manchester training academy and are fully certified.

Yes we are always happy to help and also provide after care support when needed.