Guide to Digital Surveillance Systems
What you'll need to know - but they don't tell you

Self-Serve Bays -

Good, tight seals and waterproof construction are required in the harsh Bay environments. Large outdoor housings don't work well in bays because of the tendency for the large glass plate on the front to get dirty and scaly pretty quickly. Small format cameras work well here because they tend to be even more moisture resistant than the larger cameras in housings, and their small lens glass sheds water better with longer intervals between cleanings. Avoid the tiny bullet cameras that some companies sell, as they are a poor choice for any wet location since they have a bad reputation for condensating and fogging on a regular basis.

Automatic Bays or Tunnels -

This is the most extreme environment for any camera so get one that is specially built for this environment and it will last years. The wrong camera for this location can be rendered useless in a few weeks by the constant moisture, fast changing temperatures and corrosive effects of the chemicals scaling the front glass. A camera made for this environment should be small in size, high resolution, have a Varifocal, or manually-adjustable lens, and have a built-in heater that comes on at temperatures of 60 degrees or lower to combat condensation and fogging. Also ask if the glass lens has a special coating that is designed to resist chemical etching. This type of lens coating means you won't have to clean it as often, and the scaling deposits will be easier to remove.

Perimeter areas or outlying views -

Cameras that are mounted on the wash structure and looking out at outlying areas need to be the large type in the traditional outdoor housings. This is for several reasons. First, since the lighting tends to be dimmer the farther you get away from the bays, the lens surface area needs to be larger so that the camera can gather more light. Secondly, the large camera housings are more visible and tend to be a deterrent to criminals. Color cameras are fine for looking toward well lit areas such as Vacuum islands, but when pointing the camera toward darker areas, or when using the camera to pick up license tags, a Day/Night version that will switch to a black & white picture is really valuable since it can see better under dim lighting conditions.

Lenses are the most important part -

The human eye is an incredibly adaptable device that can focus on distant objects and immediately re-focus on something close by. It can look into the distance or at a wide angle nearby. It also has a long 'depth of field', therefore scenes over a long distance can be in focus at the same time.

By contrast the basic lens of a CCTV camera is an exceptionally crude device. It can only be focused on a single plane, everything before and after this becomes progressively out of focus. This single focus point must be predetermined and that is usually not a guarantee that an occurrence that you want to see will happen in that area. Therefore, the selection of the most appropriate lens for each camera must frequently be a compromise between what you expect to see and the practical use of the system. It's not feasible to see the whole wash bay and be able to read all the license tags with one lens. The solution may be to add more cameras or to compromise with a lens strength that is somewhere in between.

One of the best lens types to work with when you install your system, is the "Varifocal", or manually adjustable zoom lens. This type of lens gives you a small amount of adjustability to "fine tune" each scene, whereas a "fixed lens" camera is pre-set to a particular view. As adaptable as the Varifocal lenses are, I'm always tempted to use them everywhere. However, depending on which area of the wash you want to cover, they're not always the best choice when considering both price and effectiveness.

The following is a list of the most common types of lenses used and where I have found they work best:

Fixed Lenses -

View is fixed and cannot be altered: Least costly and usually comes standard with a 3.6mm lens (see sidebar for lens views) or can also be ordered with other options as well. A simple camera to use. Arrives pre-set and pre-focused so all you have to do is hang it, plug it in, point it and you're done. Used for short distance shots and general wide-angle views. Ex: Equipment rooms, changers, vending, doors, bays, etc.

Varifocal lenses -

Small amount of adjustability is provided to get the correct width and distance: Available for about $50 more on most cameras. The amount of adjustability varies with each lens, but try to get a camera with a 3.5mm to 8mm range for Bays, a 2.8mm to 12mm range for wide-angle views of outlying areas, and a Telephoto range of 5mm to 50mm or more when using the camera to capture license tags.

Figure 1 - Approximate view of each lens size in a 15' x 15' room.

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Allen Spears has been in the Car wash business for more than 15 years, and currently owns 4 washes in Texas. Allen is also the Chief Engineer at CarWashCameras.com (a division of Rugged CCTV), for the past 12 years, and has designed systems for over 1600 car washes during his career. He can be e-mailed at allensp@carwashcameras.com, and can be reached at 1-866-301-CCTV