Why do security cameras don't have a clear image? like in a convenience store, etc.?

Like the answer above mine, the recording is mostly at fault, some places use VHS, so compression on hard drives is not always the problem.





Another isssue that needs to considered is that cheap security camera's have a small aperture, that's a small hole that the light can come in. As in photography a small hole means that you have greter depth of field. A shop owner can install these camera's anwhere without worrying about having to focus them. It is very common for them to be this way. Having a small hole brings everything into focus for sure, but there is a draw back, not much light can get through that little hole, so the sensor that picks up the light needs to be very sensitive ( think high ISO). These chips cannot do a good job of this without creating a lot of digital noise. This noise ends up on either the computer hard drive or the VHS tape.





Either method a company uses, hard drrves or tape, is going to cause issues and once combined with cheap, small aperture camera's and well, you end up with what we have today. More expensive camera's are better of course, but require more attenttion to them. I am guessing that the local convience store owner just wants a cheap and easy to use system.Why do security cameras don't have a clear image? like in a convenience store, etc.?
Another problem is poorly placed cameras. Rather than taking the time to ensure the cameras are placed where they are certain to get a crisp image on a specific area - such as tight on the front door, the cameras are placed where they can cover the most area. Rather than worrying about covering the entire building, a store should ensure it has good pictures on the entrance/exit doors and near the office and cash registers.





One strategy that would be useful is to use one or two cameras to give a wide view of the entire location and then have cameras that can give you a good crisp view of the places where a persons face is most likely to be seen. Using split screen views, you can then track someone through a building until they get to the point where you have a crisp shot.Why do security cameras don't have a clear image? like in a convenience store, etc.?
It is usually the way the images are recorded, not the cameras, that are the problem. Some stores use the cheapest cameras they can find, which doesn't help.





Compression is the problem. The store is trying to record (usually) several cameras and keep that video for (usually) a few weeks at least. They have to do this in a limited amount of hard drive space. So they crank the compression up to maximum to save space, at the expense of decent quality video when they need it.





I've had this discussion with a lot of store owners/managers, when they get mad because the person robbing them can't be identified off their crappy video footage.
The basic answer is that most users of security cameras try to cover too much area with each camera. A camera can provide good detail of a small area, or a wide angle view of a larger area, but not both.





The situation is often compounded by the use of low quality cameras, uneven lighting, and the use of excessive compression settings in the video recording system.





There is an excellent document that explains the use of CCTV cameras for surveillance purposes available for free download at http://www.transitcommtech.com/files/cct鈥?/a>
My stepfather has a CCTV camera from back when he used it to 'scan' images into his ancient computer. I've used it to feed video through the television and I can tell you it has great quality. I have seen SOME video from security cameras that is pretty good. So most people likely skimp on the hardware. There's also that compression issue brilliantly described by a previous poster.
Video focused on infinity.