Buying A CCTV System, DVR or IR Night Vision Camera

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Buying A CCTV System, Camera or DVR ?

This guide has been written to help buyers make an informed decision when purchasing CCTV equipment. The purchase of CCTV equipment, be it on Ebay, an Internet Site or from a Retailler, can be a daunting prospect which is not helped by the ammount of jargon, misrepresentation and listing "errors" for specifications.

This guide will focus on identifying the most common listing and specification "errors" that abound on both Ebay and Ecommerce sites and is based on the most common questions we get from buyers.

Please take time to vote for this guide if you find it helpful. In the past some guides have only received negative votes by sellers affected by a guide's contents in an attempt to reduce their relevance and visibility to other buyers.

It is worth noting that there are many genuine, experienced CCTV companies on Ebay but unfortunately they seem to be outnumbered by those which use questionable item descriptions, specifications, claims and "shipping from" locations. It is for this reason that we are not refering directly to any of our products in an attempt to make this as independent a guide for buyers as possible.

DVRs - Digital Video Recorders

For a more detailed breakdown of DVRs, please see our other guides - the following are just some points to be aware of when choosing a system to suit your needs and most of these points a made seperately in our other guides.

Frame Rates are the most misquoted figures for DVRs - an example is a current Ebay item which is for an "8 Camera Complete System" which states "live Recording at 25 Frames (images) per second per camera".
Whilst not completely incorrect - this description is exceptionally misleading. - whether deliberate or due to inexperience on the part of the seller.

A buyer reading the description would assume that 8 cameras recording at 25 Frames per second would mean this was a 200 Frame unit - ie: 25 Frames X 8 Cameras = 200 Frames Recording. However when you read the actual specification for the DVR (in this case a link to the manual in the listing), you find that the DVR has a maximum record rate of 50 Frames per second.

The 25 Frames per second is actually based on what is termed CIF recording - the image below is the easiest way to explain this but basically it means the cameras only record at 25% of the actual image size. Full screen resolution is termed as D1 which is Full Size Image capture. No professional member of the CCTV or Security industry would recommend this - obviously recording at only 25% of the image size means lower resolution images and pixelization of images once blown up to normal D1 size for printing and recognition purposes.

Sorry image is so small - limit on Ebay.

So in effect the advertised DVR is only capable of recording each camera full size at 6.25 Frames per second, which is actually more than adequate but does no detract from the listing being misleading.

The next common "error" is the representation of available recording times. It should be stressed that all recorders are capable of recording for substantial periods of time and whilst some listings are not totally inaccurate when they quote "months" of recording time, this can also be very misleading. Unless using several terabytes of storage, to actually achieve months of recording time will involve decreasing the recording quality and limiting the frame rate substantially and also using CIF recording. An example would be the manufacturers' specification for the Avermedia 1304MD unit which states recording times of up to 2 months on a 160GB drive, however this is based on 1 Frame per second, CIF mode, lowest record resolution and the lowest motion detection sensitivity. A more realistic period based on medium motion detection, full D1 resolution and 3 frames per second would be 7 to ten days depending on whether the cameras are internal or external.

Be it a domestic or retail environment, we would always recommend using the highest recording resolution, Full D1 and if necessary scale down the frame rate to extend staorage ability. It is always much better to have a high quality image at D1 and recorded at for example 3 frames per second than a poor quality image at a higher frame rate as it is the quality of the image that will be required for identification and evidence purposes.

CCTV Cameras

Most of the following is covered in our other guides but this is again just to allow a more informed decision when choosing which camera is most suitable for your own application.

Cameras abound on Ebay, making it very difficult for most buyers to decide which are more suitable for your application. This is further complicated by some ridiculous claims and ommissions in item descriptions and even some guides.

An example of which, is the number of guides which are not written from an "independent" standpoint and refer to the guide writers' products. One guide actually states that a 1/4" Sharp 420TVL camera is "the most professional high quality camera available" and "is the camera of choice for all major retaillers and security companies". This is quite interesting as although the Sharp 1/4" CCD is commonly used in budget CCTV systems, it is definitely not the 1st choice of any professional installer or retailler I have ever dealt with in 22 years in this business unless, of course, budget demanded it.

The Normal "base" line for Pro equipment is a 1/3" Sony CCD specification with a minimum of 420TVL.

Another guide authoritively states that "that there is no merit in Black and White cameras and any resolution above 400TVL is of no benefit to the end user" also the same guide states that " Black and White cameras are never used by professionals". These statements are so ridiculously incorrect that either the comments have been copied from some very, very old CCTV guide or the seller is not from the industry. Our camera guide explains a lot more with reference to why black and white cameras are not usually suitable for domestic and retail clients but are used, almost exclusively, by professionals for very specific reasons. Black and White mono cameras are like any other camera when it comes to TVL resolution and the higher the res, the better with some units producing 750TVL - resolutions outside the range of most colour CCTV Cameras.

Infrared "night vision" cameras are probaly the most popular units at the moment which is why they appear to be the subject of so many misleading descriptions. It should be noted that IR light is very reflective so when a camera is tested by a manufacturer, the tests are normally conducted internally which allows reflection of IR from ceilings, floors and walls thus increasing the perceptible range. Therefore a camera which states a 30m range will, when used in an external environment will only produce an effective range of 7~15m normally leading to disappointment of a buyer if the seller has not quoted the effective range.

Another misconception is the IR spread of light - IR cameras produce a beam of IR light similar to that of a torch so when a listing claims 30m of IR on a camera with a wide angle 3.6mm Lens, the seller seems to be "unaware" that a unit with a 3.6mm lens will not produce any effective image capture at a 30m objective distance.

Below is a quick method of determining the lens required to capture images at different distances. It is for this reason that on most domestic systems a 3.6mm or 6mm fixed lens camera is ideal but on larger or in more difficult environments, a varifocal camera which allows adjustment of the focal length of the camera is recommended.

The focal length combined with thesize of the image sensor (1/3" or 1/4") will give you the viewing angle. A smaller focal length will give a wide-angle view and a large focal length will give a narrow field of view. Wide-angle lenses have a better depth of field than longer range lenses. This means the camera can focus up close to the camera as well as at a distance. Telephoto lenses require a more precise focus adjustment. The calculation for working out focal length is:

f=h x D/H - Where h = Image Sensor value,
1/4" Sensor: h=3.6mm
1/3" Sensor: h=4.8mm
1/2" Sensor: h=6.4mm

Where f = Focal Length
Where D = Distance

Also, if you wish to find the width of objects that you can see after a certain distance you can use this formula:

H=D x h/f

Example: What can I see at 10ft distance if I have a camera with 1/4" sensor and 4mm lens (fixed focal length)?

H=D x h/f
H=10 x 3.6/4

The above shows how misleading a description which claims to give a 30m IR range on a Sharp 1/4" 420TVL 3.6mm camera actually is.

Last but not least, try to use sellers that provide a support number and that are prepared to answer any tech questions by phone or through ebay messaging with proper responses.

Please be aware that although there are many systems advertised as being located in the UK - always check the negative or neutral feedback as a number of sellers falsely claim item locations in the UK when they are actually in China.

This poses several issues - first of which is the quality control of some products - this is why the majority of professional CCTV distributors only source from Taiwan or Korea, countries that do not promote any form of enforced labour. This leads to better quality control procedures which is obviously important to UK sellers. UK Sellers are required by law to provide a minimum of 12 Months warranty, whilst there is very little a buyer can do legally if a product from a source in China fails after a couple of months. Secondly, as you will see in these type of listings, there will also be a declaration that the seller " bears no responsibility for any import tax or duty". As numerous feedback on these sellers shops show, this can result in custom charges of £200+ for some buyers - the problem is that the sellers mark the customs forms (quite illegally) as low value gifts and not suprisingly UK Customs are more than aware of this practice. This then means that the buyer becomes responsible for all import duty and VAT on Goods - currently up to 13.9% import duty on some equipment and another 17.5% VAT on top of that again.

Finally - for tech support and returns, you will always be better buying within Europe - the cost of returning an Item to China is expensive eg. a 2KG package (camera and packaging) to China is £27 by Royal Mail International signed for and insured - 2KG is the maximum allowed via Royal mail so a DVR weighing 8KG will require a courier, currently 8KG  - box 75cm by 30cm by 75cm to China via Parcelforce is an unbelievable £206.19 ~ £265.69 depending on service chosen - priced parcelforce's website 18:10:08 - package is worked out on a volumetric basis by their site hence cost.

Hopefully this guide has been of some use - if so please vote, as mentioned earlier several guides like this only receive negs by sellers (who actually use the practices outlined above) in an attempt to limit the visibility of these guides to buyers.

If you have any specific questions, please contact us via Ebay messages, E-mail or on our Local Rate Number in our listings - Please Note: all customers are given an 0800 Freephone support number but we have had to remove this from our listings due to the number of calls from people seeking technical support on products not purchased from ourselves.

Many Thanks

Tech Support
TradeCCTV Direct

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