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Professional Level Systems    $390.00 
2CHP7
2CHP7
2CHP7
Frequently Asked Questions
 
Security Camera

  1. What type of security camera do I need?
  2. How does lens size affect distance and field of view?
  3. What is the F Stop?
  4. What is the difference C or CS Mount?
  5. Do I need an Auto or Manual Iris Lens?
  6. What is the Depth of Field?
  7. How to measure the Focal Length?
  8. What lens do I need covering an angle of?
  9. What is BLC "BackLight Compensation"?
  10. What is the camera format?
  11. What is an Auto Iris Lens?
  12. What is Automatica Gain Control(AGC)?
  13. What is "Lux" for cameras?
  14. Protection Classification IP 66?

  1. What type of security camera do I need?

    A security camera can come in many different styles including dome, bullet, infrared and c-mount. The security camera that will work best for your application will depend on several factors such as whether you will use the security cameras inside or out, during the day, nighttime, or both.

    Bullet style security cameras are the most popular. They can be used inside or out. These security cameras come in black and white or color and come with all of the required mounting hardware. The security cameras casings are weather resistant and don't require added external protection. Most security cameras have a fixed 4mm lens that allows you to see facial features out to about 35 feet and provides a 70 degree angle of view. This is the widest angle you can have without distorting the picture.

    Resolution levels for black and white security cameras are about 400 lines, any higher and the benefits are minimal. For color cameras, the higher the resolution the better.

    Infrared security cameras are also very popular as they allow an image to be seen in little or no lighting conditions. Most infrared security cameras are bullet style and can be used inside or out. The cameras have infrared lighting installed around the outer edge of the lens which allows the security camera to see in no light for up to 25 feet - even further with a little bit of light (like street lighting or an outside light).

    A relatively new type of security camera to the market is the day / night security camera. These types of security cameras have an extra sensitive imaging chip which allows it to capture a good picture in low light situations without using infrared led’s. This is especially handy in outdoor applications because infrared security cameras do not do well in outdoor housings. Unless the infrared security camera is installed flush up to the glass of the housing, the infrared lights can reflect off of the glass of the housing which degrades the image.

    The advantage to c-mount security cameras is that the lens can be changed. You'll want a special camera lens if you need to see further than 35 ft. The color c-mount security camera allows you to change lenses on the camera giving you the ability to zoom into a particular area. Varifocal camera lenses allow you to adjust the focus from 5 to 50 mm. These lenses can be used inside only unless you put it in special housing for outdoor use.

    Dome security cameras basically provide a different look. Also, if you have any concerns about tampering, check out our Infrared Armor Dome Security Camera. It will withstand a 10 lb sledgehammer blow and can be used inside or out, daytime or nighttime.



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  2. How does lens size affect distance and field of view?
    A smaller lens value will show a shorter viewing distance and a wide field of view. A larger lens value will allow for a longer viewing distance but a narrower field of view.

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  3. What is the F Stop?
    In photography, stops are also a unit used to quantify ratios of light or exposure, with one stop meaning a factor of two, or one-half. The one-stop unit is also known as the EV (exposure value) unit. On a camera, the f-number is usually adjusted in discrete steps, known as f-stops. Each "stop" is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop.

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  4. What is the difference C or CS Mount?
    These are 2 standard cctv camera lens mounts. Their only difference is the the flange focal distance, which is 17.526 mm (0.69 inches) for a C-mount, 12.52 mm for the otherwise identical CS-mount.

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  5. Do I need an Auto or Manual Iris Lens?

    For outdoor cameras, auto lenses are needed for lighting change.

    For indoor cameras, manual lenses are sufficient to handle a more stable lighting condition.



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  6. What is the Depth of Field?
    The depth of field (DOF) is the portion of a scene that appears sharp in the image. A large DOF leads to a large area in the Field of View being in focus, while a small DOF means only a small section of the Field of View are in Focus.

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  7. How to measure the Focal Length?

    Please refer to this formula for calculating Focal Length:

    (1/ Object distance) + (1/Image distance) = 1/Focal Length



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  8. What lens do I need covering an angle of?

    Please view the table below:

    Focal Length

    Angle of View

    2.8mm

    97.4 degrees

    3.6mm

    85 degrees

    4mm

    71.6 degrees

    6mm

    44.4 degrees

    8mm

    34.5 degrees

    12mm

    22 degrees

    16mm

    19 degrees

    3.3-8mm

    95.2-35.9 degrees

    5-60mm

    53.6-4 degrees

     



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  9. What is BLC "BackLight Compensation"?
    Many cameras included a BLC circuit. This circuit is used to help correct an image with more light behind the subject being viewed. Without backlight compensation, the subject appears dark with little detail. Using backlight compensation will reduce the brightness of the light to allow the subject to appear brighter and bring out the details.

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  10. What is the camera format?
    Refers to the size of the imaging sensor. Common formats are 1/4", 1/2", 1/3", 2/3", and 1". The size of the sensor directly affects the field of view obtained. When using the same size lens on different format sensors, different viewing areas are obtained. For example, using a 6 mm lens on a 1/3" sensor will give you a 37 degree field of view. Using the same lens on a 1/2" sensor will increase the field of view to 56 degrees and 74 degrees on a 2/3" sensor. It is important to make sure you have a lens that was designed for at least the size of your sensor. For instance, you can use a 1" format sensor on a 1/3" camera, but you cannot use a 1/3" lens on a 1" camera. If you use a lens designed for a smaller format camera, the image will be vignetted. Also, by using a lens designed for a larger format sensor, the field of view will be greater than what is specified.

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  11. What is an Auto Iris Lens?
    An automatic iris lens is a lens with a motorized iris that automatically adjusts to only allow a specific amount of light to reach the image sensor. When there is too much light, the iris will close to reduce the amount of light let in. Auto iris lenses are primarily used in applications where light levels vary and it would be impracticable to manually adjust the lens. Automatic iris lenses are generally more efficient than the electronic shutter since they actually control the amount of light reaching the sensor as opposed to simply adjusting the shutter speed.

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  12. What is Automatica Gain Control(AGC)?
    Most cameras come with an AGC circuit. This circuit examines brightness level of the video signal to keep it at a consistent level. For example, if the video signal is dark, it will attempt to increase the gain to bring the brightness up to a normal level.

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  13. What is "Lux" for cameras?
    LUX is defined as "Relative amount of light that will produce a viewable image." A unit measuring the intensity of light. Full moon light is about 0.1 lux whereas full daylight is about 10,000 lux. Most color cameras can produce decent images during deep twilight. Most black and white cameras need about as much light as produced by a full moon. With our new HAD and Super HAD CCD cameras, the only light you need is starlight on a dark night.

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  14. Protection Classification IP 66?

    The protection classification offered by an enclosure is shown by the letter IP (Ingress Protection) and two digits. The first digit indicates two factors:

        1. Protection for persons
        2. Protection for equipment

    The second digit indicates the protection against water.

    First digit: 6

    Protection for persons:

    Protection against a wire touching dangerous parts.

    Definition:

    A body 1,0 mm in diameter must not be able to enter.


    Test conditions:

    The accessing probe is pushed against every opening of the enclosure with a standardised force or is inserted through the opening.

    Conditions for acceptance:

    The protection is satisfactory if a sufficient distance between the accessing probe and dangerous parts is kept.

    Protection for equipment:

    Sealed against dust

    Definition:

    Dust must not enter at all.

    Test conditions:

    The test is carried out in a dust chamber in which talcum powder is being kept suspended in the air by means of a dust distributor or similar device. The enclosure which is being tested is placed in the test chamber while a vacuum pump keeps the pressure in the enclosure below the atmospheric pressure of the environment according to the standard.

    Conditions for acceptance:

    The protection is satisfactory if there is no visible dust deposit within the enclosure after completion of the test.

     

    Second digit: 6

    Protection against water :

    Protection against powerful water jet.

    Definition:

    A strong water jet directed at the enclosure from any direction must not have any harmful effects.


    Test conditions:

    A jet nozzle with an inside diameter of 12.5 mm splashes a volume flow of 100 litres per minute from a distance of 2.5 - 3 metres from all sides onto the enclosure. The test time is 3 minutes.

    Conditions for acceptance:

    Should water have penetrated, it must not

    - be present in quantities which impair the good working order of the operating material or represent a safety hazard;
    - deposit on non-conducting parts where it could lead to creep currents;
    - come in contact with live parts or coils which are unsuitable for operating in wet conditions;
    - collect near the wire end or possibly penetrate the wire.

    Important note:

    The protection classifications given for the enclosures refer to unmachined standard enclosures as supplied. As the tests to show protection classifications take no account of ageing, the maintenance of the protection classification throughout the lifetime of the equipment is not guaranteed.



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