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A Crash Course in Motion Sensor Cameras

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One of the most important features of modern security cameras is motion detection. While it doesn’t hurt to have cameras set up in and around the home, for those of us that have busy lives, trawling through hours of footage to find the suspect who stole a parcel from the doorstep, or, worse, knocked over the garbage can, isn’t especially practical.

Cameras with motion sensors overcome these issues by detecting motion and then notifying users, not only saving a great deal of time, but significantly improving the overall security of your property and the actual effectiveness of having a security system in the first place.

For those of you not in the know, fret not—we’ve covered all the essentials right here, so you’ll soon be a budding expert on motion activated security cameras.

What Is Motion Detection?

Motion detection determines the movement of an objective relative to its surroundings. There are several ways to achieve this, and most modern motion sensors now combine various ways of detecting motion to paint a much more accurate and informative impression of not only the fact of motion, but of what—and even who—is the cause of it.

Changes in visible light or infrared light are common ways of detecting motion; radio, sound, and even magnetism are also sometimes used, but these would scarcely ever feature in consumer grade motion sensor cameras.

Instead, many manufacturers now combine their devices or motion activated camera apps with other technologies like facial recognition and night vision, to add more features, provide users with more useful information, and to automate the home.

What Is A Motion Sensor Camera?

Motion sensor cameras are cameras that are able to detect motion through one of the aforementioned technologies. This makes them perfect for use in a security context, since they are then able to notify users of any unusual movement.

PIR, or ‘passive infrared’, is the sensor used by most motion activated security cameras. It detects infrared energy given off by living things, be it human or animal.

If there’s a rapid increase in infrared energy detected, the smart camera will start recording, or, if it’s a camera that alerts your phone, you may instead receive a push notification with the option to start livestreaming, or even the option to communicate in real-time with whoever’s on the other side of the lens.

The complexity of the motion sensing capabilities, and what the camera then does with it, depends entirely on the model. Some smart devices, for instance, can recognize contacts that you know via facial recognition technology, and some give you the option to ignore animals by only detecting heat above a certain weight. 

By incorporating different technologies with motion sensing, all kinds of possibilities for automation emerge.

Credit: Security Camera King

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Can You Turn Your Phone Into A Motion Sensor Camera?

With the overlap between camera technology and smartphones, it’s hardly any wonder that it’s now possible to have your phone act as a fully functional wireless motion sensor camera.

Aside from the various cameras that alert your phone when it detects unusual activity that are available on the market, there are also emerging options for motion activated camera apps that require no additional hardware to function.

Among the first major apps of its kind is AlfredCamera. Launched in 2015, Founder and CEO Alex Song developed the app to address a major shortfall in the market—ultra-affordable security cameras that boast the features of some of the most expensive available, including motion detection.

‘Before AlfredCamera was founded, Alex lived in a humble apartment. He was just 20 years old when he experienced his first burglary … That was when he came up with the idea of portable, inexpensive security cameras.’ 

Alex Song, Founder and CEO of AlfredCamera

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Top 5 Best Wireless Motion Sensor Cameras

If you’re in the market for wireless security cameras, it’s clearly worth finding one with motion detection. 

Here are our picks for some of the best motion detector cameras on the market.

Recommended reading: Wired vs Wireless Security Systems | A Comprehensive Guide

Arlo Pro 4 Spotlight

Available from Arlo. From $199.99.

Arlo Pro 4 Spotlight
Image via Arlo

Arlo produces a series of popular home security devices. The Arlo Pro 4 is a wireless rechargeable camera that supports up to 2K video with HDR. Connect to Wi-Fi for easy setup, and then sync with Apple HomeKit, Alexa, or Google Assistant to take advantage of automated push notifications and other advanced features.

Its weather resistance makes it suitable for indoor and outdoor usage, while the discreet spotlight and simulated night vision allows you to observe what’s going on even in low light.

Speaking of which, are you looking for a motion sensor camera with night vision? Check out our expert guide on how to choose a night vision camera.

Google Nest Cam

Available on Google Store. From $199.

 Google Nest Camera
Image via Google Store

Google’s flagship ‘nest’ product, the Nest Cam is a battery-operated wireless motion sensor camera. Chic and discreet, it’s suitable for use indoors and outdoors.

As one might expect from Google, its motion sensing goes a step beyond most of its competitors by incorporating facial recognition and other intelligence-based technologies, with the intention being to streamline and automate your home security.

Unfortunately, 24/7 continuous video history requires a ‘Nest Aware Plus’ subscription (and since it’s a security camera, it’s probably wise to record footage), but 24/7 live view is available out of the box. If you’d like go without a subscription, here is a list of security cameras that don’t require subscription

Google Nest Doorbell

Available on Google Store. From $179.99.

Google Nest Doorbell camera
Image via Google

The Nest Doorbell is Google’s answer to video doorbells. The battery-operated version is wireless and attaches to either your door or the wall adjacent to it.

Much like the Nest Cam, by incorporating built-in intelligence, its motion sensing capabilities are quite advanced. It can tell the difference between people, packages, animals, and vehicles in real time, and send push notifications based on the information it gathers. ‘Nest Aware’ uses facial recognition to even notify you when a familiar face is at the door.

Two-way communication lets you communicate with whoever’s at the door, while the 3:4 ratio, displayed vertically, maximizes what you can see, from sky to ground.


Available from the App Store and Google Play Store. Free, with the option for premium.

Image via AlfredCamera

AlfredCamera is widely regarded as among the best motion activated camera apps for Android and iOS. If purchasing a camera would blow your budget, you don’t need to sacrifice your safety and security: simply use an old smartphone as a camera.

Since Alfred can’t take advantage of any motion sensing hardware, it detects motion through graphical information from the camera stream. The algorithm itself extracts moving pieces in the scene, then applies filters to get rid of trivial motions (like a tree blowing in the wind).

When Alfred detects something unusual, it will instantly notify you, and allow you to use two-way communication wherever you are. Other features like night vision make it a totally robust means of securing your property, without the cost.

Zmodo Pivot

Available from Zmodo. From $59.99

the Zmodo Pivot 1080p Wireless Security Camera.
Image via Zmodo

If an old smartphone isn’t lying around the house, you don’t have to break the bank to get a decent wireless motion sensor camera. Zmodo offers a robust yet inexpensive option for well under a hundred dollars.

The Zmodo Pivot records in up to 1080p, using a wide-angle camera to gain maximum visibility. As the name suggests, Zmodo can ‘pivot’ in 360°, so that when significant motion is detected, you can enable a full sweep of the room recorded in a short clip. Push notifications sent to your phone will then let you see the sweep of the room.

It also happens to provide temperature and humidity reading, and act as a Bluetooth speaker, allowing for two-way communication. No doubt, you’ll be getting bang for your buck!

Credit: Techs You Can’t Live Without


What do motion sensors see?

In the context of cameras, mostly infrared energy. A PIR (passive infrared sensor) is the type of sensor that detects general movement, but an imaging sensor is needed as well in order to actually gauge information about who, or what, moved, and these sensors are in all cameras. It compares sequential images from the footage, frame by frame, to determine information based on changes to the pixels.

Do motion sensor cameras record all the time?

No. While they are on, and, therefore, ‘observing’ all the time, the advantage of a motion activated security camera is that it can be configured to only record and save footage when the sensor detects movement, thereby saving memory. Many cameras also allow for certain parameters to be changed, like only activating when objects of certain weights, sizes, or temperatures are detected.

Why is motion detection not working?

Issues with motion detection could be down to a number of different things, including incorrect settings/setup, lights or other obstructions confusing the sensor, or even a damaged circuit board.

For more on this, check out our dedicated guide and FAQ on motion detection issues. For a more general guide, learn how to tell if a security camera is on and recording.

Can a mouse trigger a motion sensor?

Unlikely, but in theory, it could. The factory settings of most commercial security cameras with motion sensors would purposely have the sensor ignore something so small.


Improving the safety of your property isn’t just a matter of installing any old camera. We live busy lives—we need technology that’s going to actually be useful to us, and that requires convenience. With that in mind, motion detection is a vital feature you’ll need to get the most out of your security setup.

Motion detection means that you can go about your life without having to think twice about sifting through potentially hours of security footage. Your device will let you know when it detects something, thereby streamlining the process and significantly improving the security of your property.

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