Choosing an IP camera starts with the scene, not the datasheet. First define what the camera actually needs to deliver: is motion detection along a fence enough, or do you need facial identification at an entrance or a readable licence plate at a gate? Only that answer determines the resolution (pixel density on the target), the lens (field of view versus identification range) and the housing (mounting conditions). Selecting a camera the other way around, from specs to scene, is the most common cause of complaints along the lines of "we have the footage, but you cannot see anything on it".
Resolution: pixel density matters, not megapixels
The question "what resolution should a surveillance camera have" is badly framed until you know the distance and the width of the scene. What makes footage usable is the pixel density on the target at a specific point in the frame. The same 4 MP camera will deliver identification-grade images in a narrow corridor and barely detection-grade images across a car park tens of metres wide.
In design practice the DORI standard helps, describing four levels of image requirements:
- Detection: you know something appeared in the frame (a person, a vehicle), with no detail.
- Observation: you can see characteristic features, for example clothing colour or direction of movement.
- Recognition: you can tell whether it is someone you already know.
- Identification: the image allows you to positively establish the identity of a person you have never seen before.
Each successive level requires noticeably higher pixel density. That is why identification zones (entrances, checkouts, gates) are designed separately from zones where detection or observation is sufficient (perimeter fencing, manoeuvring yards).
Practical takeaways: a 2 MP camera is entirely sufficient for a narrow corridor, a staircase or a small room. 4K makes sense on wide scenes (a warehouse, a car park, a yard) or at long distances, where a single sensor has to cover an identification zone far from the mounting point. Keep the hidden cost in mind: higher resolution means a larger data stream, and therefore higher demands on the network, the recorder and above all the storage at a given retention period. A "just in case" 4K camera in a spot where 2 MP is enough raises system cost with zero evidential gain.
Lens: field of view versus identification range
The second choice is the lens. The rule is simple: a wide angle covers a lot of scene but only identifies close to the camera. The longer the focal length, the narrower the frame and the further the identification zone reaches. A single wide-angle camera cannot simultaneously "see everything" and read faces at the far end of a car park.
There are two basic options:
- Fixed lens: cheaper and simpler, but the field of view has to be right at the design stage. A good choice when the scene is well defined, for example a corridor or an entrance.
- Motorized zoom: a varifocal lens adjusted remotely, without climbing a ladder. It makes framing after installation easy and leaves a margin when distances are only known approximately. The standard for outdoor scenes and higher mounting points.
Scenes with a gate, driveway or barrier almost always call for a longer focal length: the camera sits ten or more metres from the vehicle and the frame has to be tight so the licence plate gets enough pixel density. This is a typical spot for a dedicated entry camera alongside a general overview camera watching the whole area.
Housing: form follows the mounting location
The housing form is not about aesthetics but function. You will find the same variants in the "Housing" filter of our IP camera catalogue:
- Dome: compact and discreet, often in a vandal-resistant version. The natural choice for interiors, circulation routes and places where the camera is within arm's reach, for example low ceilings, lifts, retail spaces.
- Bullet: an elongated form with strong IR illumination and longer range. The backbone of outdoor surveillance: fences, car parks, facades. An extra benefit is deterrence, because a bullet camera is visible from a distance and clearly signals that the site is monitored.
- Turret (eyeball): the most universal form. Easy to re-aim after installation and less prone to infrared reflections than a dome, whose bubble can scatter IR and wash out the image at night.
- Panoramic 360°/175°: one mounting point instead of several cameras. It works well in large open spaces such as warehouses, yards or corridor intersections. Just remember that the pixel density is spread across a very wide frame, so it is a tool for observing the whole area, not for identification at a distance.
Additional criteria that decide difficult scenes
Once resolution, lens and housing are settled, the quality of the footage is decided by additional features:
- WDR: mandatory in backlit scenes, meaning building entrances, gates, shopfronts. Without true hardware WDR, a person walking in will be a black silhouette against a bright background.
- IR illumination: match the illuminator range to the real distance of the scene, not the maximum value on the datasheet. For long distances consider an external IR illuminator.
- AI analytics: object classification (person, vehicle) radically reduces false alarms from animals, vegetation and precipitation, and speeds up searching through recordings.
- ONVIF compliance: guarantees that the camera will work with recorders and VMS software from different manufacturers.
- NDAA/TAA compliance: required in some projects for institutions, infrastructure and companies working with US entities. Verify it before quoting, not after.
If NDAA/TAA compliance is a requirement in your project, the natural direction is the MEGApix camera line from the American manufacturer Digital Watchdog. xProsec is the only Polish distributor of Digital Watchdog cameras, imports them directly and backs them with a 5-year warranty.
Frequently asked questions
Is a 4K camera always better than 2 MP?
No. The better camera is the one that delivers the required pixel density in the identification zone at an acceptable data stream. In a narrow corridor 4K adds nothing except storage load, while on a wide car park 2 MP will not allow identification. The starting point is always a scene analysis, preferably against the DORI levels.
When should I choose a motorized zoom over a fixed lens?
When you only know the scene distances approximately, when the mounting point is high or hard to access, or when the framing will need correction after commissioning. Remote focal length adjustment lets you fine-tune the identification zone without sending a crew back on site. For well-defined, close-range indoor scenes a fixed lens is sufficient and cheaper.
Turret or dome for outdoor surveillance?
Outdoors the turret usually wins: there is no bubble, so at night there are no infrared reflections and no problem of a dirty dome degrading the image. Choose a dome where vandal resistance and a discreet, flush look are the priority, for example at low mounting heights within arm's reach.
Need cameras matched to a specific site? In the xProsec catalogue you can filter CCTV devices by resolution, lens, housing and analytics, and our engineers will help you put together a complete system. Contact us and we will prepare a specification for your project.