Author: Mike Norton
Some of the blurb explained
We provide a wide range of quality cameras to suit all situations. The options can be quite confusing however for those new to security systems. To use an example: one of the products we recommend is the HikVision product for a simple to use, plug and play surveillance solution. The majority of the Cameras provided by HikVision have a fixed or Vari-Focal lens and a 1/3” Progressive Scan CMOS Sensors with a 0.07 Lux without IR or 0.0 Lux with IR.
WOW! What did I just say???? The following highlights may explain this a little better…
The most important thing to consider when choosing your camera, barring quality of image, is the Lens size. The Lens size will depict what area your camera covers, and by this I refer to the cameras FoV (Field of View). The smaller the lens size the wider the FoV and closer the focal length; the larger the lens size the narrower the FoV and further the focal length. The following chart give an approximate overview of how this affects the FoV.
This is only a coarse overview as each camera make is different depending on the chipsets and configuration that the manufacturers utilise.
A fixed lens size is a predefined lens size that gives you a fixed FoV (Field of View). You really need to be sure of the application as once you have this camera you are then locked into the coverage it can provide. As a rule of thumb our HikVision 2.8mm Domes will cover 90 degrees at a close proximity – rooms and the front of premises; and our 4mm bullets will cover a little more distance but at 75 degrees – sides of houses and driveways etc. Having the lens size locked in will save you $$ as these cameras are a lot cheaper than the Cameras with Varifocal lenses.
Varifocal lenses, whilst more expensive, give you the option of changing the lens sizes once the camera is in its position, therefore increasing or decreasing the FoV. These are much more versatile and allows you to adjust the FoV once installed. These cameras are ideal for obtaining specific/localised fields of view and generally can be adjusted from 2.8mm through to 12mm. They are ideal if you want to cover Cash Registers, doorways to recognise faces or want to focus in on number plates for number plate recognition.
CCD and CMOS sensors - the camera`s retina
There are 2 types of camera sensor:
CCD sensors (charge coupled device), are more expensive to produce but the image quality is generally higher needing less electronic "touching up", depending less on the recording unit to do the work. Most professional cameras tend to use CCD technology.
CMOS (complementary metal oxide semiconductor) sensors depend a lot more on the recorders technology, to clean up the image to obtain a higher quality result.
1/4 inch or 1/3 inch CCD Sensor - why 1/3 inch is better?
This measurement refers to the size of CMOS or CCD image sensor used in a camera. Smaller image sensors are less sensitive to light and are more likely to suffer image deterioration or "noise". 1/4 inch sensors measure 7.68mm² (3.2mm by 2.4mm). 1/3 inch sensors measure 17.28mm² (4.8mm by 3.6mm). So a 1/3" sensor is 225% the size of a 1/4" sensor - a significant increase. Try to buy cameras with 1/3” sensors, particularly at the lower end of the market where manufacturers will be fitting cheaper DSP’s (chipsets).
Just because a camera claims to have a Sony 1/3 inch CCD sensor doesn't make it a good camera. You need to know exactly what electronics have been used and then ensure it has the most suitable lens for your application.
DSP (Digital Signal Processor or sometimes called the chipset) - the brain of the camera
As with the human eye, light enters the camera through a lens, it then hits an electronic sensor - the equivalent of our retina. This sensor turns the image into an electronic signal. The electronic signal goes to a processor called a DSP or "chipset" where it is processed and adjustments made for different light conditions, the DSP does the same job as our brain in the human eye comparison.
The type of processing chipset or DSP is equally as important as the CCD sensor. HikVision have worked very hard to come up with the best combination to suit individual cameras. Ability to capture footage in low light levels, how adaptable the camera is to different lighting or climatic conditions and ease of use are all affected by the choice of DSP. A lot of manufacturers go way overboard when packing DSP based features in their cameras to the point where even professional installers don`t fully understand them. We like a nice simple "does what it says on the box" solution with settings automatically selected by the camera.
Lux Levels - how well a camera performs in low light or infra-red light
This refers to how much light is required for the camera to be able to "see". We have chosen the HikVision brand so as to ensure our cameras can see down to 0.07 lux when the infra-red lighting is turned off within the camera. Their sensitivity also ensures superb results when the camera`s built in infra-red lighting is turned on. When evaluating cameras we notice massive differences in low light performance. Some cameras artificially "boost" light levels resulting in images that have maximum boosted levels. These images are very poor because as well as boosting the subject they also amplify "noise" and other unwanted parts of the image
WDR – Wide Dynamic Range Settings (only available on Digital Cameras)
Traditionally analogue CCTV-Cameras can only apply brightness controlling mechanisms and technologies to the entire video image. This is where Wide Dynamic Range comes in as the WDR Function is able to treat different areas in the image individually and apply separate brightness modifications within the same view.
Wide Dynamic Range Applications
Not every camera in a CCTV System needs to incorporate WDR functionality. Applications are scenarios in which stark contrasts and differences in darkness and brightness within the same image view can be expected. A typical scenario:
- Exit/Entry Doors: A camera is focussing in visitors entering the building through glass doors. The background outdoor scene is very bright and the camera uses AES or an Auto-Iris to tune the overall image brightness down. This results in the display of too dark faces of the entering visitors and facial details are lost. The CCTV Installer activates the Wide Dynamic Range function => The outdoor area brightness is tuned down without affecting the image area displaying the customer
Camera Location options
Whilst we there are a myriad of installation options for CCTV Cameras when you place mounting brackets into the equation, the following is a simple overview of the basic cameras out of the box options.
The Dome surveillance camera is predominantly installed internally, although with all of our cameras having an IP rating of 66 (water proof rating) you can install these externally too. This camera is ideally mounted in the horizontal mounting position (either as a ceiling type mounting or with a wall mounting bracket) as if it is mounted vertically then you cannot move the lens from left to right without rotating the cameras view. As a result, if mounted this way, you are restricted to vertical adjustments only.
Generally we install Bullet cameras to external FoV’s that require a narrow distance view. EG driveways, Car Parks and doorways. This camera has a very versatile FoV once mounted as they can be pointed in any direction 360 degrees.
These are the type of camera you would traditionally associate with CCTV. Not the best looking camera in the world, they need a special housing if you want to protect them from the elements, are more prone to damage and can sometimes take a bit of setting up. Camera bodies and lenses are usually sold separately.
Fisheye lens cameras are the latest and greatest in the CCTV world. They provide a complete 360 degree panoramic view of the world and predominantly come in the 5MP range. They need some smart software to decipher the data streams into a coherent presentation that we can review efficiently but, as you can imagine, a single fisheye camera in the middle of the ceiling for a shop or room will give you full room coverage.
Feel free to ask any questions by dropping us a line or calling 1300 004 226