Sentry Motion Detector Camera

Sentry turns a phone you already own into a motion detection camera that works in the dark.

Set it down, arm it, and walk away. When something moves, it records. When the movement stops, it stops. The clips land in your gallery, ready to review whenever you want.

It records for you to watch later. It is not a live video feed: you are not watching a stream, you are collecting what happened while you were not there.

WHAT IT IS FOR

Find out what your dog does to the sofa while you are out. See which animal has been visiting the garden after dark. Watch how a sleeping cat actually gets from one end of the room to the other. Use a spare phone as a security camera on the garage overnight and check the footage in the morning.

BUILT FOR THE DARK

Most cameras give up when the light does. When the scene gets dark, Sentry lets the frame rate drop so the shutter has time to stay open, and brightens the exposure to match. The result is usable footage in rooms where the standard camera returns noise.

The screen stays dark while it runs. Monitoring goes on for hours, often overnight, and a bright display would waste battery and light the room you are trying to film.

RECORDING IS ALWAYS VISIBLE

A red dot sits in the corner of the screen for as long as recording lasts. There is no setting to turn it off, because there should not be one. Photos play the camera shutter sound.

YOUR FOOTAGE STAYS ON THE DEVICE

No account. No sign-up. No cloud. No subscription. Recordings are written straight to your gallery and never uploaded. Sentry sends only anonymous crash reports and usage counts, never images or video, and it works with the phone in airplane mode.

HOW IT WORKS

1 tap: photo
2 taps: start recording
3 taps: arm motion detection, which begins after 5 seconds and stops 1 second after movement ceases
Swipe up: cycle the rear lenses
Swipe down: front camera
Two fingers, 5 seconds: stop, after confirming
Shake: settings

Long sessions are saved in chunks as they record, so a flat battery costs you minutes rather than hours.

RESPONSIBLE USE

Record only where you have the right to. Laws on recording people vary by country and by state, and some places require the consent of everyone present. Sentry shows a recording indicator that cannot be disabled and plays the shutter sound on photos, so anyone who looks at the device can tell it is capturing.

REQUIREMENTS

Android 8.0 or later. Extended recording and motion detection use significant battery, so keep the phone on a charger for long sessions. Video files are large, so check free space before a long run.

Privacy Policy: https://bigballi.com/privacy

Recent changes:
Fixed a crash on some phones with more than one rear camera.
The telephoto zoom button is back, so you can jump straight to your zoom lens again.
New: watch and control Sentry from another phone on the same Wi-Fi, Android or iPhone. Pair once by matching a code, then see a live preview. The camera shows LIVE VIEW while someone is watching.
Short motion clips on slower phones now save reliably instead of failing.