The act of securing a door or a premise is rather a very complex one and that which cannot be limited to a single device no matter how complex or how good looking it might turn out to be. There are many factors that need to be considered before turning to a solution that can best provide the needed result.
Getting to see the other side
In the case of a peep hole, be it a digital peephole viewer (tuerspion.net), it is true that the primary function is to get to observer what is lying or what gets to come up to the door front. It does thus provide a sense of security that few devices this simple can provide. For a lot of people that abhor the unknown it is only natural that it brings them great comfort to know what lies beyond the normal visible horizon and that is essentially what the peep hole does.
There are of course the more sophisticated peep holes that incorporate a call bell or at times a device to transfer some sort of basic conversation. This is rather an extended function to a peep hole that might be more a psychological function than any true benefit to the user. With the limitations in place there really cannot be a practical side to the fitting as might be.
The peep hole as a deterrent
Often when intruders or potential intruders approach a particular premise the very existence of a peep hole does make them vary so to say. They would be on the tender hooks as to what to expect next. This is only natural as there are very innovative methods of preventing intrusion that are not just effective but can cause bodily harm to the intruder. Thus the sight of a digital peep hole itself in many ways is a way of announcing the intentions to a potential trespasser to the property.
The first line of defense
The digital peephole can be made an effective first step towards preventing a break in and does offer an intruder an impression that the house hold does not take security of the premises lightly. Thus it does act as a first line of defense that would also manage to convey a certain message to keep the area under surveillance safe and secure at best.
With the range and kinds of home defense system available in the market there is no telling the precautions that have been deployed at a site on just arriving at the entrance. There is a type and kind of protection for every budget and cost available that it is now mostly a common thing to deploy a digital peephole.
Depending on the final aim of a person residing in a property and his budget to deploy for protection systems it is possible to have digital peepholes that vary in complexity and working to suit the very requirements. A judicious mix of technology and budget constraints is what gets to decide on the system to be used at a premise on most occasions.