Types of cameras
Cameras can be classified in terms of whether they are designed for indoor use only or for indoor and outdoor use. An outdoor camera needs to be protected from the weather, an external, protective housing may be required unless the camera design already incorporates a protective enclosure.
Cameras, whether for indoor or outdoor use, can be further categorized into fixed, fixed dome, covert, PTZ, and thermal network cameras.
A fixed camera is a camera that has a fixed viewing direction once it is mounted. It may come with a fixed, varifocal or motorized zoom lens, and the lens may be exchangeable on some cameras.
Fixed cameras are available with image sensors sizes ranging from less than 1 megapixel up to 40 megapixels.
1080p is currently the most common and standard format. 4K is relatively new and over time will likely replace 1080p as the most popular format. Keep in mind that in order to use 4K cameras, computers must have more processing power and storage compared to a 1080p system and the viewing monitor should be 4K in order to display the high definition images created by 4K cameras.
|VGA||640 x 480||307,200||4:3|
|720p||1280 x 720||921,600||16:9|
|1080p||1920 x 1080||2,073.600||16:9|
|3 megapixels||2048 x 1536||3,145,728||4:3|
|5 megapixels||2560 x 1920||4,915,200||4:3|
|4K||3840 x 2160||8,294,400||16:9|
|8K||7680 x 4320||33,177,600||16:9|
Did you know? More pixels does not always equal better image quality.
A 4K camera has more pixels on the image sensor compared to a lower resolution camera. Smaller size pixels gather less light which reduces low light performance and Wide Dynamic Range technology effectiveness.
Pixels Per Foot – Best Practices
In the video security industry, some best practices have emerged regarding the number of pixels required for certain applications.
For an overview image, it is generally considered that 20 to 30 pixels are enough to represent one foot of a scene.
For applications that require high level of detail, such as license plate or facial identification, pixel requirements can be as high as 75 pixels per foot in good lighting conditions, or higher, for challenging conditions and environments. Careful planning is required if you expect to be able to identify license plates or people.
Pan-tilt-zoom (PTZ) cameras
Mechanical PTZ cameras provide pan, tilt and zoom functions (using manual or automatic control), enabling wide area coverage and very high level of detail when zooming in.
PTZ cameras are available in various form factors, the most common is a PTZ dome. In outdoor installations, PTZ cameras are usually mounted on poles or walls of a building.
In operations with live monitoring, PTZ cameras can be used to follow a person or object, and zoom in for closer inspection. In unmanned operations, automatic guard tour on PTZ cameras can be used to monitor different areas of a scene. In guard tour mode, one PTZ network camera can cover an area where many fixed network cameras would be needed. Keep in mind that with a PTZ camera, only one location can be monitored and recorded at any given time.
For maximum coverage and detail consider a combination of fixed cameras to view and record everything always, and one or more PTZ cameras to investigate events in real time.
Note: A mechanical PTZ camera has an optical zoom lens that maintains image resolution, as opposed to digital zoom, which enlarges an image with loss in image quality. A mechanical PTZ camera equipped with HDTV 1080p image sensor and 32x optical zoom lens can read a license plate at 900’ distance providing there is light available.