Analog Security Camera Performance Factors:
The Type and Quality of the Imaging Chip in the camera: CCTV security cameras produce images using CMOS or CCD (Charge Couple Device) chips. Tiny and/or very low price CCTV cameras usually use CMOS technology, produce poor quality video and have very poor light sensitivity. Decent quality and better CCTV cameras use CCD technology. The size of the CCD chip is normally 1/4", 1/3" or 1/2". As a rule of thumb, the larger the size, the higher the quality of the image produced and the higher the price. However, higher density 1/4" and 1/3" CCD chips can now produce as good an image as many older 1/3" or 1/2" chips.
The Make of the CCD chip in the camera: Not all CCD chips are equal, even with the same specifications. Quality varies by manufacturer. Sony and Panasonic are generally recognized as producers of the best CCD chips. Most CCTV security cameras supplied by Sentry Security Systems use CCD chips from these two manufacturers.
The Type of DSP (Digital Signal Processing) Chip in the camera: Digital CCTV security cameras use a DSP chip to digitize the analog video stream produced by the CCD chip, in order to improve certain picture quality elements and to add additional functionality. The DSP chip in the camera can have a very large effect on the quality of the video images produced by the camera. All CCTV security cameras supplied by Sentry Security Systems Inc. use DSP chips.
Number of TV Lines: The number of TV lines in the video produced by the security camera is a measure of picture resolution (sharpness). The larger the number of TV lines, the better the resolution and hence, overall picture quality. Over 370 TV Lines is generally considered good resolution while over 450 TV lines is considered high resolution. All our CCTV cameras have a resolution of at least 380 TV lines with many well over 500 TV Lines.
Light Sensitivity: Sensitivity ratings are generally given as the minimum "Lux" levels at which the camera will produce a useable image (1 Lux equals 1/10 Foot Candle). The lower the Lux number, the lower the light levels at which the CCTV camera will produce an acceptable image. In other words, the lower the Lux level rating, the more light sensitive the camera.
Lux level ratings (and the amount of light entering the camera) are inversely proportional to the aperture of the camera iris and so are stated at a specific “F Stop” (Focal Length divided by Aperture). A camera with a Lux rating of 1.0 at F1.4 will only have a Lux rating of 2.0 at F2.0.
B/W security cameras generally have lower Lux level ratings than color cameras (i.e. B/W cameras will produce acceptable images in lower light conditions than color cameras). With the adoption of enhanced light sensitivity ExView CCD chips from Sony and Extra View CCD chips from Panasonic, we can now offer exceptionally light sensitive color cameras in both our Sentry and Mintron CCTV cameras. Our Sentry Day/Night cameras change from color to B/W when Lux levels drop below about 1.0 and produce useable B/W images down to a Lux level of about 0.03 Lux. We are also pleased to offer several Mintron cameras incorporating "frame integration". This method of electronically boosting the amount of useable light by holding the shutter open for longer, allows our "Starlight" cameras to produce a useable color image in as little as 0.003 Lux (the equivalent of the amount of light available on a starlit but moonless night).
Signal to Noise (S/N) Ratio: The higher the Signal to Noise ratio, the clearer the video image produced by the camera. Good CCTV cameras will have a S/N ratio of at least 48dB. Our Mintron color cameras have an actual S/N ratio of 60dB - much better than most while our Sentry cameras have S/N ratios of at least 50dB.
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