Door viewers

View port is used for visual control of limited space and are usually installed on doors of private and public spaces. Peephole should give a clear image of objects at a distance from 0,5 to 5,0 m in bright and medium light. Special door viewers can also provide: view space through the double doors (eyes for double doors), stealth surveillance (hidden eyes), protection of the observer (bulletproof eyes and eyes-periscopes), etc. Door viewers often overlap with television monitoring system, whose work is less reliable. It is very important to make the right choice of door peephole. Door peephole device design door viewers can be very diverse, but in all the little eyes are ocular (lens facing the eye of the beholder) and lens (lens facing to the observed object). Between the eyepiece and the lens may be other lenses. The mechanical design of the majority of eyes includes: an outer shell, the nut and inner nut. The total number of lenses in the door viewers ranged from 2 to 15. In the special door viewers are sometimes used mirrors (eyes-periscopes). The most common is the construction of the optical system, consisting of four lenses, which provides a viewing angle of 180-200 ° without significant distortion. Peephole - A device that can be used without opening the front door, to see the landing. Entrance door, of course, must protect the house from intruders. Therefore, it is good to see who is behind the door. It is for this at the door put the peephole. The main characteristic of eye - the viewing angle. What it is, the better. The largest viewing angle - 180 °: then can even be seen mat lying under the door. A very small - about 120 °. Still need to know the thickness of the door. It ranges from 35 to 60 mm of conventional doors, while good, reinforced metal reaches 85 mm. Therefore, the "trunk" of eyes do different lengths and different diameters, so that you can set the eye at every door. In addition, each eye is a thread that regulates the length. Eye optics may be glass or plastic (of course, glass eyes, better, stronger, less glass is scratched), and "body" makes a metal or plastic. The material from which made the eye, affects the quality of the eye, and the price. According to specialists, eyelets, metal and glass of the most reliable, but also the most expensive. Note: buying cheap Russian spy hole, whose diameter is greater than, say, the Spanish have to drill a large hole in the door. And replace it with a peephole with a smaller diameter will be very problematic. By the way, if you bought the front door, and in the configuration indicated the presence of a door peephole, it does not mean that it is already installed. In advance they do not stick. Why? Very simple: to avoid every time they get up on a stool or a bend in three of perdition, the installation location is determined by the eye is directly mounting the door. So you need to know when choosing peephole? Longer serve a metallic eye with glass optics. It is best to immediately decide which angle you're interested in: depends on the choice of model. The same applies to the diameter of the eye - decide this in advance, so you do not have to think like a larger diameter hole to insert the eye of a smaller size. Viewing angle door peephole. Given the crime situation, this characteristic of door peephole is crucial. The ideal angle for door viewers is 180 °. Wide viewing angle is achieved by "removal of forward focus of the lens. Only in this case provides full view of the space behind the door. However, keep in mind that the door viewers on the edges of the field seems often there is some image distortion. Therefore, most wide-eyes are made from inflated viewing angle - 200 °, which reduces distortion in "working" sector - 180 °. It must be remembered that the thickness of the door more than 55 mm. the use of "standard" buds leads to a drastic reduction in the visual field. In this case, you must use door viewers high luminosity is larger diameter. Hyped now videoglazki and intercoms do not provide a complete inspection of the space behind the door. In videoglazkov real angle is typically less than 150 °, while the intercom, the figure is only 50 ° - 70 °. The thickness of the door - one of the main parameters of door viewers. On this parameter eyes are divided into three groups: standard eyes (door thickness 30-55 mm), elongated eyes (door thickness 55-100 mm), extra-long eyes (door thickness over 100 mm). The bulk of the manufactured door viewers is "standard." These eyes can be installed on modern standard wooden doors and metal doors, whose thickness does not exceed 60 mm. When you select "extended" or "very long" door viewers should remember that these eyes should have different optical characteristics than the "standard" eyes. It is not always the case. Some manufacturers produce "extended" eyes, we complete a "standard" eye of an elongated rear nut without changing the optical circuit. Setting eyes with a complete set on a thick door leads to a sharp decline angle. Choosing the peephole, you should check it out on the viewing angle, as unscrewing the nut inner eye, ie, optimizing the parameter "door thickness. If the doors are finished by various hard and soft materials, the length of 'standard' eyes may be insufficient. In this case, you must install the "extended" or "extra-long" door viewers. The design of the damper At present, almost all door viewers are equipped with flaps. Without dampers are made only cheap products. The flap does not transmit light from the flat and allows the observer to secretly come to his eyes and secretly monitor. Basic requirements for product design. The flap should be tightly closed hole eyepiece easily and silently opened and closed, do not have sharp angles and its movement does not touch the door or door trim. The latter requirement is often not provided in the design of modern eyes, and leads to difficulties with rotation flaps, damage the surface of the door, cut the soft upholstery of doors and, ultimately, failure of the damper. Materials used in the manufacture of door viewers, largely determine the selling price eye. Material optics for door viewers divided on glass and plastic. Glass optics made from optical, "points" and ordinary glass. The best material is the optical or "points" glass, while a conventional glass somewhat worse results on the transmission of light, which affects the luminosity eye. Glass optics manufactured mechanical grinding and polishing and is virtually everlasting. Plastic Optics - Optics is the cheapest option. It is manufactured by injection molding of transparent plastics. Plastic lenses have several significant drawbacks: prone scratches, due to the electrification of static electricity and attract dust, and finally, most plastics over time, changes its shape and yellowing, loss of transparency. Practically, the second or third year of operation of door viewers with plastic optics are deteriorating sight in these eyes. Material mechanical parts of door peephole is divided into plastic and metal. Plastic parts are used in cheap mass-produced little eyes. Over time, they can warp due to the release of internal residual stresses. In turn, metal eyes differ from each other in the form of metal processing method and type of coverage. The cheapest door viewers are from siluminovogo casting, which is usually only the front nut is covered with paint. Eyelets, machined, have a better appearance and more value. At the same types of coating, eyes of non-ferrous metal more expensive buds of black metal. The type and quality of coverage depends largely on the appearance of buds. And, very often eye of black metal with a coating looks better than the eye of non-ferrous metal without the coating. For example, door viewers, brass "gold-plated" darken over time, and door viewers of steel coated with chromium, titanium nitride, and then - not darken and virtually scratch-prone.