When choosing a security camera, most people focus on resolution, such as 2MP, 4MP, or 8MP.
But there’s another important component that often gets overlooked: the CMOS sensor. The CMOS sensor plays a major role in determining how well a security camera captures images, especially in low-light conditions. In this article, I’ll explain what a CMOS sensor is, how it works, and the different sensor sizes commonly found in modern security cameras.
Understanding these features will help you choose a camera with night vision capabilities that best suit your needs.
What Is a CMOS Sensor in a Security Camera?
The CMOS sensor captures and processes the light coming through the camera lens.
Generally, the larger the CMOS sensor, the better the image quality, especially in low-light conditions. That’s why security cameras designed to capture color images in near-darkness often use larger sensors, such as a 1/1.8-inch CMOS sensor.
Here are the common CMOS sensor formats:
| Format Type | Nominal Diagonal (mm) | Nominal Width × Height (mm) | Typical Applications |
|---|---|---|---|
| 1/4″ | 4.5 | 3.6 × 2.7 | Low-cost surveillance, webcams |
| 1/3″ | 6.0 | 4.8 × 3.6 | Security cameras, drones |
| 1/2.8″ | 6.4 | 5.1 × 3.8 | IP cameras, machine vision |
| 1/2.7″ | 6.7 | 5.4 × 4.0 | Automotive ADAS, robotics |
| 1/2.3″ | 7.7 | 6.2 × 4.6 | Action cameras, drones |
| 1/2″ | 8.0 | 6.4 × 4.8 | Compact cameras, drones |
| 1/1.8″ | 8.9 | 7.1 × 5.3 | Surveillance, robotics |
| 1/1.7″ | 9.4 | 7.5 × 5.6 | Embedded vision, Video-conferencing |
| 2/3″ | 11.0 | 8.8 × 6.6 | Global shutter machine vision |
| 1″ | 16.0 | 12.8 × 9.6 | Global shutter machine vision |
| 1.2″ | 19.3 | 14.6 × 12.6 (1.16:1) | Large-format machine vision, industrial inspection |
| 4/3″ | 21.6 | 17.3 × 13.0 | Micro Four Thirds cameras |
| APS-C | 28.2 | 23.6 × 15.6 (3:2) | DSLR, cinema cameras |
| Full Frame | 43.3 | 36.0 × 24.0 (3:2) | Cinema, professional video |
These CMOS sensors are commonly paired with lenses featuring wide apertures, such as F1.0 or F0.8, to produce brighter video at night.
What Is Lux in Security Cameras?
One specification commonly highlighted by security camera manufacturers is the lux rating.
In simple terms, lux indicates the minimum amount of light a camera needs to capture a usable image. It’s also common to interpret a camera’s lux rating as an indication of its light sensitivity. A camera rated at a low lux level, such as 0.01 lux, is generally claimed to perform well in dimly lit environments. Lux is the SI unit of illuminance, equivalent to one lumen per square meter (lm/m²). You’ll often find this measurement in security camera specifications, with ratings such as 0.1 lux, 0.3 lux, or 1.0 lux.
To get a better idea of how bright 1 lux actually is, let’s look at a few everyday lighting conditions:
| Condition | Illumination (Lux) |
| Direct sunlight | 100,000 – 200,000 Lux |
| Full Daylight | 10,000 – 90,000 Lux |
| Overcast Light | 1,000 Lux |
| Office Light | 400 Lux |
| Dusk Light | 100 Lux |
| Twilight | 10 Lux |
| Deep Twilight | 1 Lux |
| Full Moonlight | 0.1 Lux |
| Quarter Moonlight | 0.001 Lux |
| Overcast night | 0.0001 Lux |
Security cameras with night vision capabilities often advertise extremely low lux ratings, sometimes as low as 0.0001 lux. This indicates that the camera is designed to operate in extremely dark conditions, although its ability to produce a usable image also depends on the type of night vision technology it uses.
How CMOS Sensors, Lux and Aperture Work Together?
Aperture refers to the size of the opening in a camera lens that controls how much light enters and reaches the image sensor. Think of aperture as the pupil of the human eye. It opens wider in low-light conditions to let in more light and becomes smaller in bright conditions to reduce the amount of light entering the camera.
Common Aperture szes in security cameras:
- F0.8
- F1.0
- F1.6
The aperture sizes listed above are commonly found in security cameras designed for advanced night vision, such as Hikvision ColorVu and Dahua WizColor models. These cameras use wide-aperture lenses to let in more light, helping them produce brighter, clearer images at night.
Security cameras without color night vision typically use lenses with an F2.0 aperture.
Image Quality Comparison: 1/1.8-Inch vs. 1/1.2-Inch CMOS censors with F1.0 aperture under identical indoor lighting conditions (approximately 0.5 Lux).
Let me explain how they work in simple terms.
At night, when the surroundings are dark, a lens with an F1.0 aperture allows more light to enter the camera. The CMOS sensor then captures and processes that light, converting it into electrical signals that are used to create a digital image. The signals generated by individual pixels are read row by row and sent to processing circuits, where they are converted into digital data. Finally, this data is processed and combined to produce a complete image.
Introducing Dahua WizColor X: A Full-Color Night Vision Camera
Previously, color night vision security cameras had six common limitations:
- Light Pollution
- Interference From Flying Insects And Dust
- Short Visual Distance
- Motion Blur
- Image Noise
- Overexposed License Plate
To improve nighttime image quality, Dahua has introduced a new technology called WizColor X. It’s the company’s latest development in color night vision, designed to help security cameras capture clearer, more detailed, and more colorful images in low-light conditions.
At the heart of Dahua’s WizColor 2.0 technology is WizColor X, designed to significantly improve light sensitivity and deliver richer colors and finer details in low-light conditions. It also enhances the camera’s ability to capture and recognize moving objects, helping to minimize motion blur.
Here are its key features:
- UltraSight Lens: Features an ultra-wide F0.8 aperture, allowing 1.6 times more light to enter the camera compared to an F1.0 lens. This helps deliver sharper images while capturing more light in low-light conditions.
- Larger Pixel Sensor: Increases the pixel size to 4 μm, giving each pixel a photosensitive area 1.9 times larger than the previous generation.
- AI-ISP 2.0: Improves image processing and motion detection using an AI model with billions of parameters and a training dataset containing hundreds of thousands of samples. It also uses reference-frame segmentation and motion direction estimation to improve object tracking in the current frame, helping reduce motion ghosting in challenging conditions.
Berikut adalah hasil video yang dihasilakan dari kamera Dahua WizColor X:
Dahua security cameras featuring WizColor X technology:
- IPC-HFW2449TL-S-PROX
- IPC-HDW2249TH-S-PROX
- IPC-HFW2249TL-S-PROX
- IPC-HDW2449TH-S-PROX
Not all Dahua security cameras have been upgraded to WizColor X yet, even though the technology was officially introduced on April 15, 2025. However, the introduction of WizColor X marks an important step forward in color night vision and could help meet the growing demand for better nighttime surveillance in the years ahead.
Conclusion
From now on, don’t choose a security camera based on resolution alone. Pay attention to its lens aperture and CMOS sensor size as well.
With CMOS sensors, a smaller fraction generally indicates a larger sensor, which can capture more light. Similarly, a lower F-number means a wider lens aperture, allowing more light to reach the sensor. Together, these features help security cameras produce brighter, clearer, and more detailed color images at night. If you’re looking for a security camera with good color night vision, I’d recommend choosing one with at least an F1.0 aperture and a 1/1.8-inch CMOS sensor.
I hope you found this article helpful!