Neo Coolcam PIR Sensor

Hi there,
Case: I am using a couple of Neo Coolcam Pir Sensors. Also I have bought the Steinel 230volt Pir Sensor. The idea is that my ptz ip camera points in a certain direction (preset) when a pir sensor triggers.
This however results in a lot of false triggers. These sensors, esspecially the steinel trigger randomly. There never a recording of an actual moving heat source.

I googled a lot about this Pir topic. It should trigger om heatsources - people / animals. But it looks like the movement of leaves or even the changes in shades on a cloudy day seem to trigger these pis sensors.

Question: is it true that any kind of movement triggers the pis sensors? Can it be that object heated by the sun also generate enough heat to set these things of?

Is there any other way with a different kind of sensor that exclude these things and only react to people and animals?..

thanx a lot,

regards,