Choosing IR Cameras
Purchasing Infrared or any other CCTV cameras or equipment online, through Ebay or other web sites, can sometimes be a daunting and confusing process. We have written this guide at the request of several customers who thought it would be beneficial to other buyers. As always, if you have any specific queries or require advice on choosing equipment, please contact us.
IR Cameras – The basics
An Integrated Infrared Camera, as used in the CCTV Industry, is a camera capable of capturing colour images in normal light and black and white images in low light or complete darkness using infrared LEDs which are controlled by a photocell on the camera.
The ability of the camera to switch from colour to black & white with IR sensitivity is achieved through either the electronic manipulation of the received images, by means of a mechanical IR cut filter or by a combination of both methods.
The Wavelength of Infrared light is measured in nms and IR illuminators used in CCTV are within the range 730~950 nms. The most widely used spectrum for integrated cameras is 840~850nms – this produces a slight red glow at the camera but otherwise is invisible to the human eye. While 950 nms produces no visible glow, it requires a camera with very high IR sensitivity to produce images at this wavelength and range can be greatly reduced.
Common Listing “Errors”
Numerous sellers on the Web significantly overestimate the IR range of their products and do not explain the variables that greatly effect the useful range of IR illumination. It is not uncommon to find listings claiming 30m, 50m and even 100m IR ranges for cameras that will, in most environments, produce only 10-15m of useful IR image capture.
When a manufacturer states the specification of an IR camera, the testing has most probably been conducted in an indoor environment. As IR light is reflective, any IR illumination benefits from the effects of reflection on walls, ceilings and floors, hence increasing range. When the same camera is placed in a working environment, such as externally on a domestic or commercial premises, the IR range is significantly reduced.
Other claims such as “extra large” or “xx number of Leds” should not be taken too much into consideration, as a lot depends on the manufacturing of the camera. Eg. A camera with 18 Leds may produce the same range as a unit with 50 Leds – the range will be determined by the quality of the camera and the Leds used in the manufacturing process.
It should also be noted that IR cameras produce a “Torch Beam” of infrared – so if you need to see an object 20m from the camera, using a True 30m range camera with a 3.6mm lens will probably not produce the results you require, as the wide angle lens will not produce a good focussed image at that distance.
Another distinction to look for when choosing a camera is on the front glass panel – traditionally, manufacturers stopped Infrared “bleed” ( IR light seeping onto the lens – causing poor images or “White Out” at night), by using small foam or rubber tubes fitted flush against the camera’s viewing window. Most modern and higher specification cameras now use a solid Anti-Bleed ring which is embedded in the front viewing pane. This embedded system is a far superior method of preventing IR Bleed and will ensure better camera operation with both short and long term use.
Physical Characteristics of IR Cameras.
As most integrated IR cameras tend to be used externally, an IP Rating of 65 or more is generally required.
What Connections are fitted to the camera ? – while units such as sports/ bullet cameras tend to be fitted with RCA connections , BNC connections are the industry standard worldwide for professional CCTV Cameras and equipment.
Please do not judge cameras by appearance, there are numerous companies manufacturing cameras from different components and, whilst 2 cameras may look identical, the quality of components can be very significantly different. Photographs will not show the manufacturing quality or in fact the construction material of the camera, with several cameras that may look similar to professional equipment, being constructed from polycarbonate or other plastic materials.
CCD Image Sensors
Within the CCTV and Digital Camera industries, "CCD" is (erroneously) used as a synonym for the type of image sensor fitted in a camera even though, strictly speaking, "CCD" refers solely to the way that the image signal is read out from the chip. However, it’s use in specifications is now so commonplace, that it is now used as a means to identify the Manufacturer and resolution of camera’s image sensor.
While a Sony CCD based CCTV camera will produce excellent quality image capture, the branding of the image sensor is not the only factor to be taken into consideration when choosing a camera. There are other manufacturers, notably Sharp and LG, who produce image sensors, and whilst their CCD sensors tend to be used in economical units, they are not without merit and should not be dismissed. The size of the sensor is equally important – normally 1/3” and ¼” on CCTV Cameras. The TVL describes the horizontal resolution of a camera – the higher the number the higher the resolution.
Unfortunately, these specifications can also be used to mislead buyers, with claims of 500TVL etc, being listed. A quality Sony 480TVL or 420TVL will normally have a spec. of more than (>480TVL, >420TVL). Sometimes, sellers appear to have taken it upon themselves to regard and sell such cameras as 500TVL+ and 470TVL.
Before You Buy!
As with all purchases on E-Bay, the Web or High St., buying CCTV equipment requires some consideration as, if it seems too good to be true, it probably is, so the following are always worth noting.
What is the Sellers Feedback Rating ? – bearing in mind this will not reflect equipment that goes faulty after several months of use.
What is the actual Returns Policy? Always read the returns information at the end of the listing as provided by E-bay very closely as it may differ from that stated in the sellers blurb.
What are the postage costs and policies? Numerous sellers who claim to be distributors are actually drop shippers and do not have immediate access to stock. These listings will normally claim a “testing” period prior to shipment or will not offer a fast courier service. It is also wise to note that when a listing states a delivery time of 3-5 days or that the courier service is EMS, it is probably being shipped from Asia.
How legitimate is the seller. This can normally be judged by the listing blurb – being VAT and company registered, does not in anyway give an indication as to the seller’s experience, customer service levels etc. so always ensure there is a working telephone number for pre and post sales advice. Also be wary of listings which spend too much space “running down” other products as legitimate businesses who sell on e-bay will rarely use such practices and will merely draw attention to specifications.
What payment methods are accepted ? – whilst E-bay prefers PayPal as do many sellers – what other methods of payment are accepted. Does the seller accept payment by credit card directly – whilst not a guarantee – a seller who can accept credit cards directly has a merchant account and their business has satisfied the security requirements of their banking institute for direct acceptance of Credit Card payments – Very few legitimate companies do not accept Direct Credit Card Payments.
We hope this guide has been helpful - if you have any specific queries or would like advice on choosing CCTV equipment - please contact us and we will be glad to help.
The Support Team