Short answer
At close points such as doors, corridors and cash registers, 2 MP is often enough. In gardens, parking lots and large halls, 4 MP strikes a good balance. 8 MP (4K) makes sense when you want to watch a very wide area with a single camera and zoom in afterward. Before megapixels, decide what the camera will see and from what distance.
What do megapixels tell you, and what do they not?
Megapixels tell you how many millions of dots an image is made of. A 2 MP camera gives 1920x1080 video, a 4 MP camera usually 2560x1440, and an 8 MP camera 3840x2160. The more dots there are, the later the detail breaks down when you zoom into the footage after recording.
But megapixels alone do not decide quality. How wide the lens looks, how much light the sensor collects, the compression setting and the camera's mounting angle matter at least as much as resolution. If you point an 8 MP camera at a whole wall with a very wide-angle lens, a face 15 meters away is still made of only a few dozen pixels and cannot be recognized.
So when buying a camera, the first question should not be how many megapixels it has, but what it will show at what distance. With the same budget, fewer pixels but a better sensor and the right lens give more useful footage at most points.
If the datasheet has no sensor size or lens information, it is hard to predict that camera's performance in advance.
The real measure: pixels on the target
In the security industry, the DORI concept is used to evaluate a camera by its purpose. The letters stand for detection (is something there), observation (what is it doing), recognition (is this someone I have seen before) and identification (who is this person). The number of pixels that must fall on one meter of the target is different for each level; identification needs the most pixels.
Manufacturers state in the datasheet of most cameras at what distance these four levels are achieved. When choosing a camera, looking at these distances instead of megapixels gives a more accurate result. For example, if you want to identify someone coming through the door, the camera's distance to the door must stay within the identification distance in the datasheet.
With the camera distance tool on our site, you can roughly calculate how many pixels fall on the target with a given lens and resolution.
Expert note: Reading license plates is a separate job. A wide-angle general camera rarely reads the plate. Placing a separate narrow-angle camera aimed at the plate on the entry lane gives more reliable results.
Which points suit 2, 4 and 8 MP?
The matches below are a general starting point. The final decision is made by distance and lens.
- 2 MP: places where the camera is a few meters from the target, such as a shop cash register, a door entrance, a narrow corridor or a stairwell.
- 4 MP: a detached house garden, the common area of a housing estate, a medium-sized parking lot, store aisles. A balanced choice for most homes and businesses.
- 8 MP: places where a single camera is expected to cover a large area, such as a factory yard, a wide area inside a warehouse or a school yard.
- License plates and distant identification: the lens matters more than resolution; consider a narrow-angle or motorized-lens camera.
The price of high resolution: disk and bandwidth
As resolution goes up, the data the camera produces per second goes up. To keep the same recording time, a bigger disk, a more powerful recorder and sometimes a faster network are needed. A NVR that does not support 8 MP cameras, or whose total input capacity is not enough, forces the camera to record at a low setting and the point of high resolution is lost.
Newer compression methods such as H.265 store the same image with less data. Both the camera and the recorder must support this method. When watching from a phone, too, the low-resolution secondary stream is used instead of the high-resolution main stream, so your mobile data does not run out quickly.
Decide in advance how many days of footage you want. You can find the disk calculation in detail in our article explaining how many days camera footage is kept.
Night image and sensor size
When more pixels are fitted onto a sensor of the same size, the light falling on each pixel decreases. That is why a cheap high-resolution camera can give a grainier, blurrier image in the dark than a good 4 MP camera. If night image matters, look at the sensor size, the lens aperture value (such as F1.0 or F1.6; the smaller the number, the more light it takes in) and the infrared illumination range.
On summer nights in Şanlıurfa, there is little light in gardens and parking lots other than street lamps. A camera that works well in the dark, rather than a very high resolution, is often more useful for recording an incident that happens at night.
The recorder, screen and cable must be compatible too
After choosing the camera, you need to check the rest of the chain. The highest resolution the NVR supports per channel, the total input bandwidth and how many channels it can decode at high resolution at the same time are stated in the datasheet. A device that lets you connect eight 8 MP cameras may not be able to show all of them smoothly at the same time on the live view screen.
The viewing screen counts too. If the monitor in the security room is Full HD, you cannot see the live image of a 4K camera in full detail. This is not a problem, because the detail is stored in the recording and you look at it by zooming in after an incident. Still, knowing this difference when buying the screen sets the expectation correctly.
With IP cameras, high resolution also puts a load on the network. The uplink port of a switch to which many 8 MP cameras are connected, and the NVR connection, must be fast enough. With analog HD cameras, remember that high-resolution models can lose image on long, poor-quality coaxial lines.
Common mistakes when choosing
The most common mistake is putting the same camera at every point. The door and the garden have different needs. At the door, 2 MP and the right angle are enough, while in the garden a 4 MP wide angle, and at the parking lot entrance a narrow-angle camera, gives better results.
The second mistake is trusting the megapixel figure in the catalog and not checking at what setting the recording is made. After installation, check the camera channel's resolution and bit rate on the recorder. The third is hanging the camera higher than necessary. No matter how many pixels there are, in an image shot from above you see hair instead of a face.
During the site survey, Desa Bilişim measures the target distance for each point and recommends which resolution will be enough based on that distance.
Frequently asked
How many megapixels should I get for a home camera?
2 MP for the door and entrance and 4 MP for the garden and wide areas is enough in most homes. What really decides is how far the camera is from the point you want to see and how wide its lens is.
Is an 8 MP camera always better?
No. It needs more disk space and a more powerful recorder, and night image quality can be weaker in models with small sensors. If you do not need to watch a wide area with a single camera, a good 4 MP camera gives a more balanced result.
Does a plate become readable as megapixels go up?
Not by itself. To read a plate, the camera must look at the vehicle with a narrow angle and the right height and angle. In most cases a separate plate camera is used.
The right resolution for every point
Let us walk through the points where you want to place cameras together, measure the distances and state the suitable camera for each in a written quote.
