It's not nice when your doorbell rings and you don't know who's on the other side. You can call yourself anything, introduce yourself - anyone. The voice can be faked. Only by seeing the otherworldly guest with your own eyes, you can open the doors. In the Middle Ages, a viewing slot, like a loophole, served for this. Today - a peephole. However, eye to eye is a big difference.
First of all, you should decide on the viewing angle of the eye. If it is not enough, one of the intruders may simply sit down - and now he is no longer visible, and the second one rings at the door, with a "trust-inspiring face" (two strangers at the door are always more suspicious than one).
Therefore, the optimal viewing angle of the door peephole starts at 180 degrees. Security experts advise choosing 200 degrees - due to the fact that at the edges of the view this angle gives less distortion. In this case, it will be possible to consider the entire visitor, down to the shoes on their feet. Material from whicha peephole was made, it is also of no small importance. Say goodbye to plastic immediately and forever: cheap but inefficient. Electrifying plastic, like a magnet, attracts dust to itself, moreover, over time, the optical properties of plastic slowly but inevitably deteriorate. It is better to put it once, but "for centuries". Then pay attention to the union of metal and glass, optical or spectacle. Only the metal should be coated so as not to darken over time.
Another important safety detail associated with the peephole is a curtain that closes it from the inside. The fact is that the door peephole itself is able to give out to the criminal whether the owners are at home or not, by changing the lighting in its lens. However, if you first bring your face closer to the eyepiece of the eye, and then open the shutter, for the outside, the lens will remain dark. To work effectively, the shutter must tightly cover the eyepiece opening, and when opened, not make a single sound.
Of course, there can be no question of any noiselessness if a child is left at home. After all, in order to look through the peephole, he first needs to bring a chair into the hallway, and then climb on it. The problem is solved by a more complex, but also safe device such as a periscope. In this case, the eyepiece of the peephole is located at the level of children's growth. The last of the considered optical options, the most suitable for both adults and children at the same time, is a panoramic door peephole. His eyepiece is replaced by frosted glass, on which, as on a screen, the entireviewable area in front of the door. The image on the screen is perfectly visible from 1.5-2 meters.
Approximately from the mid-90s of the last century, electronic devices began to actively spread in Russia, which were previously installed only at protected sites. They made it unnecessary to go to the hallway to the doorbell. Indeed, if a digital camera is looking through a peephole, a glance at the computer screen to which it is connected is enough. Or the camera can generally be placed on the landing so as to view it all (and more than one if desired). And if you add an infrared lamp, then the unscrewed lighting bulb will not help the criminals. The added microphones and speakers will allow you to negotiate with the visitor/s, again without leaving your computer, with which you can also record video just in case…However, do not forget that the stairwell is a common room use, and covert filming is prohibited by law.
