Topic: The CCTV Camera (a long story… made short and simple)
Myth: You can see details far away and near from the same camera:
Truth: All high-resolution cameras, analog or digital, will only resolve details of a face within 20-30′ of a camera, depending on the lenses described below. The reason for this is that the pixels that make up the face are too small as a percentage of the total picture on the screen. Camera placement as well as the number of cameras will greatly impact the ability for details such as a face to be identifable.
With hundreds of models, shapes and size to choose from most of this variety is in response to specific needs and limited applications. Most manufacturers’ claims are overstated and the cost of CCTV cameras varies greatly.
The majority of CCTV security cameras are available in three basic lens types, referred to by their lens millimeter size (lens millimeter size will vary slightly depending on the brand of the camera):
The widest angle (2.8 mm) will cover more space with less detail. It will see about 90 degrees, showing good detail up to about 20’ from the camera. This camera is useful in smaller areas and rooms such as stairwells and elevators.
The standard angle (3.6 mm) will see less space with greater detail. It will see about 75 degrees, showing good detail up to 30’ from the camera. This camera is best for corridors and medium-sized rooms.
The vari-focal (4-9mm) will see the least amount of space with the greatest detail. This lens brings images that are further away, closer. The degree of vision will vary based on the millimeter the lens is set to. These are adjustable for tighter shots of subjects where greater detail is needed up to 50’ from the camera.
Lens types for these cameras are available in traditional box, bullet and dome models of various types and are known as fixed cameras.
However, the model/style that fits the vast majority of applications perfectly come in “sealed generic dome style housings,” which are maintenance-free, weatherproof, and vandal proof (made of metal). There are no brackets to reposition as a result of weather or tampering and no lens to keep in focus. They also have built-in inferred illuminators, which provide a black and white picture down to complete darkness in limited areas when light is unavailable. It is always best to have the lens look through flat, clear, tempered glass rather than curved, tinted, and plastic surfaces- a feature of the model described above.
Other less popular types of cameras:
- Other Vari-focal and longer focal length lens– used to see license plates of stationary vehicles and detail for distances of 80-100’ from the camera. The limitations of these cameras are their narrow field of view in favor of detail at a distance.
- Digital cameras vs. Analog cameras– digital camera technology came around about six years ago, as IT people tried to “add a value and business” by entering the security market. They predicted this new technology would take the industry by storm. However, the storm came to them (unless in very high-tech, high budget environment) the costs of this technology is still very high, the functionality is very low, and no one supports them for the average user. Analog cameras installed correctly create pictures live, recorded, and remotely transmitted, just as useful as any digital cameras with many other benefits to the end-user, with support being high on that list.
- Pan, tilt and zoom cameras (PTZ’S)– are most useful in systems where there is a security command and control center/room or someone whose job it is to watch cameras live. This pricier type of camera is controlled remotely through software (joysticks in the past). Cameras are movable in real-time from side-to-side, up and down, and are able to zoom “live” in and out optically to very high levels of detail (with no pixilation) from up to two hundred feet from the camera. A limitation of the PTZ camera is once it moves it only records what it sees. PTZ cameras come in a variety of focal powers know as 10X, 22X, and 36X (larger the number the further it can see detail) and there are indoor and outdoor versions. PTZ with inferred do not exist and do not work well in low light.
Note: standard fixes lens cameras can be zoomed into digitally (with a certain amount of pixilation when zoomed into very close to the subject). PTZ cameras are often overused when its use is not clearly defined to an honest, CCTV professional.
Camera resolution specs: (lines of television resolution “TVL”) is a misused and overstated nomenclature, as it relates to the modern CCTV camera systems of today. Distributors and dealers advertise product specs with complete disregard of being able to hold camera manufacturers to actual standards. The industry is in the permanent pursuit to sell its products. It has become expected with all technical products’ specs to keep topping itself with higher and higher “ratings” of some kind or other to keep stimulating business. However, useless measurements that do nothing to enhance performance are misleading and confusing. The conflicting technologies of analog cameras and digital video recording devices render claims of cameras having over 500 lines of resolution.
Mega pixels or digital cameras bring other compromises to the table and are not solutions for most CCTV system applications.
Beware of CCTV products made in China. They will be cheaper but for a reason. These products have the reputation like in most industries of using lower quality raw materials, less experienced labor, and less quality control than other countries. CCTV Cameras have many parts like image sensors, lenses, motherboards, inferred sensors, housing, weather seals and adjustment functionality, all with the ability to sacrifice performance and longevity for a cost.