The first week you check every alert. By the second month you swipe them away without looking, which defeats the purpose entirely. A camera that cries wolf is worse than no camera, and the fix is mostly about telling it where and what to look at rather than how sensitive to be.
The short answer
Draw tight activity zones that exclude the road, the pavement and any tree, because most false alerts come from things outside your property. Then enable person detection if your camera offers it, and only reduce raw sensitivity as a last resort, since lowering it too far means missing the events you actually care about.
What actually triggers a camera
Most consumer cameras detect motion by comparing successive frames, or by sensing changes in infrared heat. Both are triggered by a long list of things that are not people:
- Vehicles and pedestrians on a road or path within view.
- Trees and shrubs moving in wind, which is the commonest single cause.
- Shadows sweeping across the scene as the sun moves, and clouds changing the light level.
- Insects flying close to the lens at night, lit by the infrared illuminator. These look enormous to the camera.
- Spiders building webs across the lens, attracted by the insects that are attracted by the infrared.
- Rain and snow falling through the infrared beam.
- Pets moving through the scene.
- Heat sources such as a car engine cooling or sun on a wall, for infrared-based sensors.
Draw tight activity zones
Exclude the road, the pavement, a neighbour’s driveway and any tree. Include only your path, your door and your own property. This is the single most effective change and it costs nothing.
Enable person or object detection
If your camera or plan supports it, filtering to people removes the majority of nuisance alerts at a stroke. Vehicle and animal categories are useful too if you want to keep some and drop others.
Clean the lens housing and clear webs
Infrared illuminators attract insects, insects attract spiders, and a web across the lens produces constant triggers all night. Wipe the housing every few weeks and this problem largely disappears.
Reposition to avoid the sun's path
A camera facing east or west gets swept by low sun and long shadows twice a day. Angling it slightly downward, so the sky is out of frame, reduces both glare and shadow triggers significantly.
Move the infrared illuminator away from the lens if you can
Insects fly to the light source. A separate infrared floodlight mounted away from the camera means the insects gather there rather than in front of the lens. This is a genuinely effective fix for night-time alert storms.
Set a notification schedule
Many systems let you notify only at certain times, or only when nobody is home. Alerts while you are in the house watching your own front door are rarely useful.
Increase the cooldown between alerts
A longer gap between notifications means one event produces one alert rather than six. You still get the recordings; you just get told once.
Reduce sensitivity last, and only slightly
This is the blunt instrument. Lower it a little if zones and person detection have not been enough, then test by walking through the scene to confirm you are still being detected.
Always test after tuning. Walk the route an actual visitor would take, then check that you got an alert and a clip. It is very easy to tune the false alerts down to zero and the real ones along with them, and you will not find out until it matters.
Camera placement decides most of this
Tuning settings can only do so much with a badly placed camera. The principles that matter:
- Mount at about 2.5 metres, high enough to be out of reach and low enough to capture faces rather than the tops of heads.
- Point across the approach rather than along it, so people walk toward the camera and it has time to wake and record.
- Keep the sky out of frame, which prevents both glare and constant exposure changes.
- Avoid pointing at a road if you possibly can, since every passing vehicle is an event.
- Never point an infrared camera through glass, which reflects the illuminator straight back and produces a white haze.
- Consider what is behind the scene, such as a neighbour’s gate or a busy path, which will trigger constantly.
Be aware of privacy rules where you live. Cameras that capture a neighbour’s property or a public footpath carry legal obligations in many places, and a tight activity zone is often both the practical answer to false alerts and the right thing to do.
The night-time alert storm
If alerts cluster between dusk and dawn and the clips show blurry white blobs, those are insects flying close to the infrared illuminator. The camera cannot tell a moth two centimetres away from a person ten metres away, because both fill a similar share of the frame.
Three fixes, in order of effectiveness: mount a separate infrared floodlight a few metres from the camera and turn off the camera’s own illuminator; fit the camera under an eave so the lens is shaded and less attractive to insects; and clean the housing regularly so webs never establish. The first one essentially eliminates the problem.
Why do I get alerts at night with nothing visible?
Insects flying close to the infrared illuminator. They are centimetres from the lens and fill enough of the frame to register as large moving objects.
Is person detection worth paying for?
If your camera faces anything busy, yes. It removes most nuisance alerts at a stroke, and it is usually the difference between a camera you pay attention to and one you ignore.
Should I just lower the sensitivity?
Only after zones and person detection, and only a little. Sensitivity is a blunt control and turning it down far enough to stop false alerts often stops real ones too.
Why does my camera trigger on shadows?
Motion detection compares frames, and a moving shadow changes a large part of the image. Keeping the sky out of frame and angling downward reduces this considerably.
How high should a camera be mounted?
About 2.5 metres. High enough to be out of reach, low enough that you capture faces rather than the tops of heads.
The bottom line
Draw tight activity zones that exclude everything off your property, then turn on person detection. Those two remove most false alerts without reducing sensitivity at all. For night-time storms, move the infrared source away from the lens. And always walk the scene afterwards to confirm you are still being detected.
