Pythagoras Lives!

Article #

Dear Charlie,

My partner dropped you a note a couple of months ago. I also decided that I wanted to see if I could ask you for your opinion on a problem we are having. We are having a problem with the image quality of some of our cameras, I wanted to know if you felt that the height of the cameras can affect the quality of the image the camera will produce. For example will a box camera in a
housing set at 12 feet on a building versus the same camera set at 18 to 20 feet on the building produce a different quality image or will it only produce a different angle.

Thanks for any response you give me.

Sign me:
Upper Vision Blues

Dear UV,

Actually, you question comes down to the Pythagorean theorem unless you change lenses. That is, A2 + B2 = C2 where A is the distance from the object of view, B is the height of the camera and C = the true distance of the camera from the object of view. This in simplest terms means that the higher you mount your camera (based upon comparisons listed by you) the farther the camera is moved from the object of target. The farther the camera is moved away, the smaller the object of identification becomes the smaller the object becomes, the less overall resolution or detail the object will have the less detail, the crappier the picture.

In your case, you took a camera at 8' feet high and moved it to 20' feet high. Let's assume the distance from the mounting position to the object of view was thirty feet as measure at ground level. The true center of the 8' high camera would be 31 feet while the true center of the 20' high camera would be 36 feet. Not a significant number, but it could be enough to drive the quality of your image down a bit.

If there is anything else that I or my staff can do to assist you in your CCTV needs, feel free to holler at any time. We are in your service.

Charlie

A = 30' = 30 2 = 900'
B = 40' = 40 2 = + 1,600'

C 2 = 2,500' or 50'

Always calculate your lens requirements as

Based upon C as opposed to A.

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