One of the main complains of people who own a CCTV system is that certain cameras are blurry or foggy at night. Criminal activity mostly happens at night so fixing your blurry cameras is a must-do task. There are a few reasons why a security camera may be blurry or foggy at night (or daytime). Here we will discuss this issue and offer suggestions on how to fix a blurry security camera.
Most of the time, this problem is related to the IR (infrared light) reflecting on the glass of the camera or on reflective objects that are close to the camera. The lights will bounce back and blind the camera lens.
You need to address this reflection issue in order to eliminate the blurry problem.
The IR Reflection/Bleeding problem
At night the security camera’s IR (infrared) light turns on to illuminate the area and “see in the dark”. This light sometimes gets bounced on objects and comes back to the camera lens. This light reflection makes the image to appear blurry or foggy. Depending on the placement of the camera, the image may be so blurry or foggy that the footage is basically unusable.
Take a closer look at the picture above. Can you see the IR reflection? In this case, the light is bouncing on the camera dome and it’s coming back to the lens thus causing the blurry or foggy effect you see only at night time. This type of reflection also occurs on other types of cameras such as bullet style, PTZs and positioning systems which have a glass in front of the lens.
As long as the security cameras are using infrared lights at night, there’s a chance of light bouncing back to the lens. You need to investigate what could be causing that and what the solution for such a problem.
The causes of the IR bouncing problem
There are a few things that can cause the IR bouncing back to the camera lens on a security camera. The most common ones are listed below:
1. Scratches or dust on the camera dome/glass
Luckily this is an easy one to fix. Check if your security camera has some dust, grease or even fingerprints on the glass and wipe it clean You won’t believe how many times this simple procedure solve IR reflection problem. If the camera is placed on a dusty environment, it will get dirty pretty soon. It’s always recommended to clean your cameras once in a while.
It’s common to have a dome camera with fingerprints left by installers since the installation occurs during the day and the problem doesn’t really show up immediately. Make sure the camera dome or glass is clean at installation time to avoid re-work.
2. Reflection from objects close to the camera
Reflective objects such as metal, glass, doors, solid fences, etc can bounce the light back to the security camera lens. Even plants can be a cause of light reflection. The best practices to avoid this problem:
a. Don’t place security cameras in tight corners.
b. Avoid pointing the camera to reflective objects.
c. Move the objects that are reflecting the light (if possible).
d. Don’t leave plants in front of the cameras IR.
e. If necessary, place the camera on a different spot.
3. Missing or defective rubber ring in the camera
There’s a rubber ring around the IR camera lens that is used to avoid the IR light bleeding. Make sure this rubber is there and it’s not damaged. Sometimes the inexperienced installers or end user will remove it. At the same time make sure the rubber ring is well-positioned and sits tight against the glass.
The bad lens problem
If your camera has a bad lens then it’s pretty much hard to correct the blurry issue. During the day the camera gets light from the sun. This light has to pass through the camera dome or protective glass and depending on the model it also passes through an infrared filter (a piece of glass) before getting into the image sensor.
When the light is passing through a glass the refraction phenomenon occurs which can change the direction of the light. At night time the IR camera removes the IR filter to allow more light coming into the camera which causes a difference in the light refraction and the camera lens needs to be prepared to correct that slight difference. If you are using a non-branded inexpensive camera, that could be a problem hard to fix since the lens is part of the circuit board and can’t be easily replaced. To avoid this problem, before buying the camera check if it has an IR corrected lens.
The security camera is blurry at day and night
The first thing you should consider if your security camera is blurry during the day and night is the focus. If the camera lens doesn’t focus the light into the right spot of the camera image sensor, the result is a blurry (out of focus) image. There are different types of lenses for security cameras, but the principle is the same for all of them. Rays of light come to the lens and are directed to the camera sensor and it must converge in the correct point otherwise the image gets blurry (foggy).
Camera with varifocal lens
If your security camera has a varifocal lens, you need to adjust the focus by turning the screw in the lens until you get the image the way you want. By adjusting the focus/zoom you can make your image clear. The image below shows a varifocal lens with a screw for focus control.
Due to the fact that a varifocal lens allows adjusting the optical zoom, there’s also a focus control since the camera zoom in or out changes the focal length.
Camera with fixed lens
In a security camera with a fixed lens, it’s not possible to adjust the optical zoom, so there’s no need for focus adjustment since the camera comes from the factory with the lens adjusted to the correct distance from the camera image sensor.
But, sometimes the camera’s image may be out of the focus (blurry/foggy). Let’s say the lens was forced out of the original position and the distance between the fixed lens and the camera image sensor is not correct anymore, this can cause the blurry image.
You can try to adjust the focus by turning the fixed lens clockwise until reaching the position that is going to have the correct focus. Usually the fixed lens comes adjusted to the right position, is not usual to have this kind of problem, so be really careful to try this procedure. Besides the fact that this problem happens in rare situations, it usually happens with low-cost cameras manufactured in China.
As you can see there’s no simple direct answer to the question “How to fix a blurry security camera” but now you have a better idea of what could be the problem related to your particular situation. Read the article carefully and try to solve the problem you are facing. You might also take a look at your CCTV security camera specs to see if you can see information related to the ICR, F-number, type of lens, back focus, etc.