As a general rule, the more technology improves, the easier it is to implement and use. Morse code telegraphs that only a few people were trained to use gave way to the ubiquitous telephone.
Computer code entry, formerly the realm of the scientist and engineer, gave way to the graphical user interface, making it possible for everyone to use and enjoy the new invention.
Unfortunately, this improved ease of use isn’t always a good thing. When things get too easy, we tend to get lazy. It’s a side effect of human nature, and of course we in the video security industry are not exempt. As camera and recording technology has advanced, specifying and designing security systems has become easier and easier, making it less necessary to utilize the skills from the past and put as much time into the front end of a project.
This has had the result of placing some of those surveying and planning skills in jeopardy of being lost to the hands of time. But just because being able to pick a specific lens isn’t always necessary anymore, doesn’t mean we shouldn’t have a good grasp of the basics.
Making the sale and picking the right product are only parts of the puzzle. Camera placement, lens choices, mounting options and cable planning are all equally important to the success of a job, and gaining the loyalty of a customer.
If you’re a salesman, project manager or estimator, at some point you’re going to have to put a project together, and it will help immensely if you know what to look for. Oh, and what about that other technological advancement, IP? We’ll take a look at how that affects our system design too.
Seeing Is Believing … in You
A frequently overlooked aspect of site surveys and system design is the environment itself. Trees grow, so make sure they won’t impede the camera’s view now, or ever.
Of all the various parts of a CCTV system, the one thing the customer is going to notice above all else is a picture that doesn’t meet his expectations. He won’t care what kind of cable you used to get the picture in front of his eyes, nor will he worry about whether there’s a space in between each piece of equipment mounted in a rack. But he will know right away if he can’t see what he thought he was going to see, or if what he can see is out of focus.
Picking camera and lens combinations is one of those areas that has become far easier over time. More sensitive cameras and varifocal lenses have taken most of the work out of the selection process. It’s still important, however, to have a good grasp of some foundational concepts.
Focal length of a lens refers to two main things, the distance a lens can see clearly and the width of the scene a particular lens can see. This focal length is rated in millimeters. The lower the millimeter (mm) number, the wider the scene. As you go higher in mm, the lens becomes more telephoto, or zoomed out, and the scene width is greatly reduced.
Some of the old-timers out there, like myself, fondly remember the little cardboard wheels that allowed you to dial in the distance to your target, the size of the camera imager and the width of the scene you want to see to determine the mm needed to achieve the desired result. Technology helped us in this area with the above-mentioned varifocal lenses. These lenses allow you to manually change the focal length of a lens once it is installed. They make the process much easier, for sure.
One technological advancement in particular has brought lens selection back up to the top of the importance scale: megapixel. When a megapixel system is designed, and the desired number of pixels-per-foot has been determined, the lens focal length needs to be set in stone. If the lens is changed after the camera is installed, you may not get the resolution you need where your customer needs to see it, such as at the entrance to a driveway in order to read license plates.
On the plus side, though, it is possible to get help from technology, without totally relying on it. Lens calculators are available all over the Internet, and especially on the Web sites of manufacturers that make megapixel products.