The camera is at an angle. I was able to shim the opposite side of the smoke detector mounting base to increase the horizontal perspective by several degrees. I can see an extra 15 feet or more by making this adjustment. This is a low end camera with no night vision. The resolution is diminished over greater distances. I still like mine anyway.
Horizon but at an angle. Mine is 8 foot 4 inches high and can view people 12 foot away with out chopping their heads from the camera. I like it for my entry as it has a slight fish eye and can cover the door to the side also. It would not work in low ceiling areas. My basement is 6 foot 2 inches and it would not work at that height unless the people were sitting
If you look at the image provided by amazon. You will see the pin hole on the side of the smoke detector. It covers the room horizontally. I'd say its angled down about 10-15 degrees. Has a wide angle of coverage. The room I've installed it in is rather large. 30' X 30' installed in one corner and covers the entire room other than about a 6' radius directly below the camera.