This passive method is not as reliable as "active" motion sensors that either bounce back a radar signal or transmit light to a photodetector in the distance. See network camera. THIS DEFINITION ...

this DIY motion trigger for a DSLR is a quick and easy build, and probably loads more fun. The BOM on [Jeremy S Cook]’s build is extremely short – just a PIR sensor and an optoisolator ...

Case in point: an easy way to make your backyard, garage, or other outdoor spaces safer and more secure is with this ...