Start with the job
Before looking at specifications, decide what the camera is for. Common jobs are:
- Recognizing a person or reading a license plate at a specific spot such as a door or gate.
- Surveying a wider area such as a yard, car park or shop floor.
- Checking in, for example watching a nursery or seeing who is at the door.
- Deterring by being visible.
Each job calls for different camera specifications. A camera that covers a whole yard rarely gives identifying detail on a face at the far end, and a narrow-view camera at the door will not show what is happening in the rest of the yard. Many sites need a few cameras with different roles rather than a single do-everything unit.
Resolution
Resolution is the number of pixels in the image. More pixels can mean more detail, but the effect depends on the lens, lighting and distance. A high-resolution camera pointed at a dim or distant scene may still give a poor result. Higher resolution also means larger files and more bandwidth, which affects storage and your network. Think about what a given resolution actually shows at the distance you need and compare sample footage from similar conditions, not just the number on the box.
Field of view and lens
The field of view is how wide an area the camera sees. A wide lens covers more but makes subjects smaller; a narrower lens zooms in on a smaller zone. Fixed lenses are simple and reliable, while varifocal lenses can be adjusted during installation. Consider whether you need a PTZ camera, which can pan and zoom, or whether fixed views cover the area at lower cost and with fewer moving parts. Cameras that rotate can only look in one direction at a time, which is a limitation.
Night vision and low light
Most security cameras use infrared lighting to produce black-and-white images in the dark. Check the stated range, but treat it as a best case, since reflections off nearby walls, dust and insects can wash out the picture. Some cameras offer color images at night using ambient light or built-in white lights, which can show clothing color but may not be as strong in total darkness. Good outdoor lighting often does more for night image quality than a more expensive camera. Our page on night vision explains these differences.
Weather and durability
Outdoor cameras need to survive rain, heat, cold, dust and sometimes impact. Look at the ingress protection rating for dust and water, the stated operating temperature range, and whether the housing is designed to resist tampering. Even rated cameras can fail in exposed positions, so shelter and sensible mounting height help. Indoor-only cameras should not be used outside, as moisture and temperature swings can damage them.
Indoor and outdoor placement
Indoors, cameras usually cover entrances, stairs and valuable rooms. Privacy matters more, since they may capture family members, guests and employees. Check local rules, avoid private spaces such as bathrooms, and consider whether audio is appropriate, as audio recording carries different legal rules in many places.
Outdoors, mount cameras high enough to resist tampering but low enough to capture faces, avoid pointing straight into the sun or bright lights, and avoid neighbors’ windows and yards. Both neighbor privacy and camera placement mistakes are common sources of trouble.
Storage and recording
Decide where footage goes before you buy. Options include a local recorder, a memory card in the camera or a cloud service. Local storage keeps video under your control but is exposed to theft or damage of the device; cloud storage offsets that but often involves subscriptions and access by a third party. Motion-triggered recording saves space, while continuous recording gives a fuller record. Consider video storage needs, how long to keep recordings, and who can reach them.
Power and connection
Cameras can be powered by batteries, a plug, low-voltage cable or a single cable carrying data and power. Wired cameras tend to be steadier; battery cameras are easier to place but need recharging or replacement. Wi-Fi cameras depend on signal quality, and many cameras together can load the network. Where cabling is practical, power over ethernet is a common choice.
Smart features
Many cameras advertise person, vehicle or package detection, two-way audio, and similar extras. These can reduce nuisance alerts, but accuracy varies and some features require a subscription. Do not rely on them without testing. Facial recognition raises particular privacy questions and may be restricted by law in some places.
Questions to ask before buying
- What will the camera need to see, and at what distance?
- How will it be powered, and what happens in an outage?
- Where is footage stored, for how long, and what does that cost?
- How is the camera secured against hacking, and are updates provided?
- Can it be used with the rest of my system?
Use strong, unique passwords and two-factor authentication where available, and keep firmware current. A camera cannot prevent crime on its own, but the right ones, well placed and maintained, can provide a useful record.