Why Is My Analogue CCTV Camera Noisy at Night?

Question: Why does an analogue CCTV camera look normal during the day, but become black and white, washed out or very noisy at night?

Short answer: A black-and-white image is usually normal when an infrared camera enters night mode. Heavy grain, faded contrast, moving lines, misty highlights or intermittent picture loss are not normal. In most installations, the first things to check are voltage drop when the infrared LEDs switch on, infrared reflection, poor cable or connector terminations, and the camera's day/night settings.

At HawkVision Pro, we have more than 10 years of practical CCTV installation experience. The checks below are arranged in the order we would normally use on site, so you can isolate the fault without replacing working equipment unnecessarily.

Q: Is it normal for an analogue CCTV camera to turn black and white at night?

A: Yes, if the camera uses infrared night vision. When ambient light falls, the camera moves its IR-cut filter and uses infrared illumination. Because infrared does not reproduce natural colour, the night image normally becomes black and white.

A Dual Light camera may also offer White Light or Smart Light modes. White light can provide a colour image, while infrared mode generally remains black and white. A black-and-white image by itself is therefore not evidence of a fault.

Q: Why does the picture become grainy or noisy only after dark?

A: The most likely cause is insufficient power at the camera when its infrared LEDs turn on. During the day, the camera draws less current. At night, the additional IR load can expose a weak power supply, an overloaded distribution box, thin power conductors, a long cable run or a poor connection.

The power supply may still measure close to 12V beside the adapter while the voltage at the camera is too low. For a meaningful test, measure the voltage at the camera end while the IR LEDs are on. Use the voltage tolerance and current requirements stated for the exact camera model; do not assume that every nominal 12V camera has the same tolerance.

Q: What does a low-voltage night-time fault look like?

A: Common symptoms include:

• heavy grain or coloured speckles;
• rolling or horizontal interference lines;
• a faded, unstable or pulsing image;
• the IR LEDs repeatedly switching on and off;
• the picture dropping out when darkness falls; or
• several cameras developing the same problem at the same time.

If every camera becomes noisy together, inspect the shared power supply and its total available current first. If only one camera is affected, concentrate on that camera, its cable, connectors and immediate surroundings.

Q: Can infrared light make the image look white, foggy or washed out?

A: Yes. Infrared light can reflect back into the lens from a nearby wall, soffit, gutter, fascia, window, spider web, dust, water droplets or part of the camera's own mounting surface. This often produces a pale, misty image with very little contrast.

Clean the lens and front glass, remove spider webs and inspect the camera's field of view at night. Reposition the camera so that nearby surfaces do not dominate the IR beam. Cameras mounted behind ordinary glass should not use their built-in IR, because the glass can reflect the light directly back into the lens.

Q: Could the cable, BNC connector or video balun be responsible?

A: Yes. A loose or oxidised BNC connector, damaged coaxial cable, low-quality balun, poor pair selection or an untidy joint can reduce signal quality. The defect may be less obvious in daylight and become much more visible when the camera raises its gain in low light.

Use a cross-test:

1. Connect the affected camera to a known-good DVR channel.
2. Use a known-good short video cable and a separate suitable power supply.
3. Cover the light sensor so the camera enters night mode.
4. If the image becomes clean, the original cable, connector, power route or DVR input needs further testing.
5. If the fault remains with the camera, inspect its IR LEDs, IR-cut mechanism and internal electronics.

Do not change the camera, DVR channel and cable at the same time during diagnosis. Change one item at a time so the result identifies the faulty part.

Q: Why does very low light create extra image noise?

A: In a dark scene, the camera increases electronic gain to make the image brighter. Higher gain also amplifies sensor noise. A small image sensor, limited aperture, unsuitable exposure settings or insufficient illumination can therefore produce a grainy image even when the power and cabling are sound.

Check that exposure and gain are on a sensible automatic setting, enable the camera's supported 2D/3D noise reduction carefully, and avoid forcing colour mode when there is not enough visible light. Excessive noise reduction can smear moving subjects, while an excessively slow shutter can cause motion blur.

Q: Could the IR-cut filter be faulty?

A: Yes. Most true day/night cameras make a small click when the IR-cut filter changes position. If it sticks or does not move fully, the night image may look dark, soft, faded or incorrectly coloured. Test the camera in daylight and darkness and listen for the changeover. If power is stable but the filter does not switch correctly, the camera may require repair or replacement.

Q: What if the noise appears as horizontal bars or waves?

A: Moving bars often point to power interference, a shared power fault, poor grounding or a ground loop rather than ordinary low-light grain. Temporarily power the affected camera from an isolated, suitable local supply. If the bars disappear, inspect the shared PSU, earth paths and cable routing, particularly where CCTV cables run close to mains wiring or noisy electrical equipment.

Q: What is the fastest on-site test?

A: Bring one affected camera close to the DVR and connect it using a short, known-good video lead and a suitable dedicated power supply. Cover its light sensor to activate night mode.

• If the night image is now clean, the installed cable, connectors or power delivery is the likely cause.
• If the image remains misty, remove nearby reflective objects and clean the camera face.
• If the fault remains in a clear test area with stable power, check the camera's light mode, gain, exposure, IR LEDs and IR-cut filter.
• If another known-good camera develops the same fault on the original route, the route or power supply is at fault.

Q: What should I check before replacing the camera?

A: Work through this order:

1. Confirm whether black-and-white IR night mode is expected for the model.
2. Clean the lens and remove nearby IR-reflective surfaces.
3. Measure voltage at the camera while IR is operating.
4. Confirm that the power supply has enough total current for every connected camera.
5. Test a separate suitable power supply.
6. Swap the DVR channel, video lead, BNC connectors or baluns one at a time.
7. Check Day/Night, IR, White Light, exposure, gain and noise-reduction settings.
8. Test the camera beside the DVR with short known-good leads.
9. Only then consider a camera or DVR hardware fault.

Q: Does changing the DVR usually fix this problem?

A: Not usually. If the daytime image is clean and the problem begins when the camera's IR activates, the camera-side power supply, cable route or reflected infrared light is normally a stronger suspect. A DVR channel or compatibility issue is still possible, which is why swapping one channel with a known-good channel is part of the test.

If you are planning or upgrading an analogue system, view our analogue CCTV cameras and DVR video recorders. You can also read our guide to NVR and DVR differences before choosing a recorder.

Need help identifying the fault?

Send HawkVision Pro the camera model, DVR model, cable type and approximate cable length, along with a short daytime and night-time video. We can help you decide what to test next before you replace equipment.

Manufacturer references

• ANNKE: How to Fix Problems with Night Vision Image
• ANNKE: Troubleshooting an Abnormal Camera Image
• ANNKE: Smart Dual Light Modes for Analogue Cameras

Safety note: Isolate power before remaking connectors or opening power distribution equipment. Do not work on mains-voltage wiring unless you are appropriately competent and authorised.