Helpful Tips for CCTV Systems How (and Why) to Back-focus a CCTV Camera

One of the biggest problems encountered by people who DIY install their own CCTV systems is inconsistent focus. The most common iteration of the problem is that the image is in perfect focus in daylight, but at night, all you get is a blur. It results from a basic technical detail: during the day – or in bright sunlight –the lens iris is closed, giving you a very wide depth of field. As the light level drops, the iris opens to bring in more light. When that happens, the depth of field is decreased and images at most distances will be blurred. There is a way to combat this tendency: back-focusing your CCTV camera with the iris fully opened to provide the optimal focus for all conditions. Here’s how you do it.
Back-focusing a Fixed Lens Security Camera for CCTV Systems
Determine the distance from the camera to the scene you want to capture with the surveillance camera.
Set the physical focus of the lens to the full infinity position.
Insert a neutral density filter. This iris will open completely to allow more light and increase the depth of field to give you the most precision with your adjustments.
Set the lens focus to near and the zoom to wide.
Aim the CCTV camera at a high-contrast object that is the same distance from the camera as the scene you’ll want to capture when the camera is in place.
Turn the lens body until the object is completely in focus.
Remove the neutral filter and install the camera in place.
You should now be able to focus the camera manually to get the precise focus you want – and all of your scenes will remain in focus regardless of the lighting conditions.
Higher end CCTV systems have security camera choices with auto back focus, so this procedure is not necessary. If you’re running discount CCTV systems with a cheap surveillance camera option, you may need to fiddle with it a bit to get the settings right for optimal focus.
Need more help with setting up your CCTV camera for good focus? Most professionals who sell and service CCTV systems will be happy to answer simple questions and offer advice. And of course, if you want to be absolutely certain that everything is properly installed, you can always hire a pro to install your security/surveillance system and not have to worry about it at all.