This is the 2nd is a series of articles about getting the best possible image quality in your CCTV installation. The first article was a synopsis of things that can go wrong.
First: The lens. Do not ignore the importance of buying a quality, well-made lens from a reputable manufacturer or distributor. The lens, on the front of your camera, is the point at which your surveillance system begins. It is CRITICAL to understand that the front edge of your lens is the BEST your signal is ever going to get. The light you are gathering from the real world is captured there, and you CANNOT improve on it. You can only make it worse from here on in. Should you choose to gamble on a ”budget” lens, and lose that gamble, you are setting yourself up for failure with the rest of your project.
There are a great many things that affect the quality of a CCTV lens. The materials it is made from, the accuracy of the shape and spacing of the optical elements, the aperture and iris, whether it is auto or manual iris, etc… Personally, I find that for a startup CCTV business, it helps to have some various lenses lined up, and to know exactly where to get them. I tend to lump them in two grades. You can buy cheaper or nicer lenses, but these two cover 95% or more of all CCTV installations.
Grade 1 – Utility. These lenses are fine for some typical installations. We’re talking retail outlets, gas stations, restaurants and bars, factory floors; the list goes on and on. These people are looking for good solid relationships and cost-sensitive installations that are of good quality. You find these lenses by bench testing. Spend the $150 or so to buy 3-5 lenses of each standard size, and test them side by side. Pick the one you like, in each size, and keep a few on hand. Lens suppliers should be able to get you quality lenses quickly and with NO damage.
Grade 2 – Premium. There is a reason why National Geographic photographers carry $3,000 Kodak lenses. The reason is simple: they are worth the money. They are rugged, easy to operate, resistant to damage, and provide outstanding optical quality. There are CCTV lenses that are in this same category. In fact there are several excellent brands to choose from, but in the interest of being neutral I’ll leave them up to you to discover. If you have a high-end customer, such as a bank, casino, police office, investigation firm, etc… Don’t even THINK about skimping on your lens quality. You can throw gobs and gobs of money at an installation, and if you don’t start with great lenses, you will not have great results. Period.
That’s not to say you have to spend a lot of money. There are inexpensive high quality lenses on the market. The important thing is to have a consistent testing setup so that you can see the difference. I recommend a single 520 or greater TV line color camera wired directly into a quality CCTV specific monitor. This connection should be on a high-quality cable and less than 6 feet long. Having such a setup (that you NEVER change) allows you to evaluate lenses on the fly, checking their price vs. performance and making sure it fits your needs. A word of warning; NEVER assume that a very expensive lens is going to look better than its less expensive counterpart. You simply cannot tell until you have compared them.
