How to Select a CCTV Camera Lens
Closed circuit television (CCTV) is a type of television where video cameras are used to transmit their signal to a limited and specific set of monitors. Most security cameras use this type of system to transmit images to monitors that are watched by security personnel. In order for your CCTV system to function correctly, you will need to choose the correct type of lens. There are a number of things to take into account when you select a CCTV camera lens.
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Instructions
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Determine what type of mount your CCTV camera has. The three types are C-mount, CS-mount and board mount. A C-mount has a "1 inch diameter, threaded barrel with 32 threads per inch. The sensor is located 0.69 inches behind the mounting surface," according to Pentax. A CS-mount camera has the same barrel and diameter, but, "a CS-mount sensor is located 0.492 inches behind the mounting surface." A board mount camera consists of a lens attached directly to a circuit board and is commonly used for micro cameras.
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Choose a lens that has the correct type of iris adjustment for your light conditions. Outdoor cameras work best with an auto-iris lens that can automatically adjust to changing light conditions. If the light conditions don't change often and the lens won't need to be adjusted often, a manual-iris lens can be adjusted by hand.
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Pick the correct diameter of lens. A 1-inch lens will work with a camera that is 1 inch or smaller. A 2/3-inch lens will work on a camera-sized 2/3-inch or smaller, but will not work on a 1-inch camera. The smallest available CCTV lens is the 1/4-inch lens, which will only work on a 1/4-inch camera. Remember that a larger lens will generally work on a smaller camera, but a smaller lens will not work on a larger camera.
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Select a CCTV camera lens with a variable focal length if you will need to look at objects of varying distances from the camera. If you will always be looking at objects that are the same distance from the camera, a fixed-focus lens designed only for that specific distance will be cheaper.
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Use a mega-pixel lens if your camera is high resolution. According to Moritex USA, "Mega Pixel CCTV lenses offer greater resolution than standard CCTV lenses." Your high-resolution camera will be unable to take high-resolution images without a mega-pixel CCTV lens.
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Tips & Warnings
The smaller the focal length number of a lens is, the wider its field of view will be.
References
- Photo Credit cctv security camera. image by wrangler from Fotolia.com
