One other factor that tends to help, at least for houses during the daytime, is that there's a lot more light outside than there is inside, so someone attempting to peer in through your peephole also has to deal with reflection of the exterior light getting in the way. Also, just as the peephole makes the image outside appear brighter to you, it makes you on the inside appear dimmer to a person on the outside, by spreading the light coming out over a large angular area. An incorrectly sized unit may not be functional and will. It is critical that you choose a peephole that is the right length to fit your door. Most commercial doors are 1 3/4 inches thick, while most residential doors are 1 3/8 inches thick. So they wind up getting a magnified view of a small part of your eye, basically. Measure the thickness of your door, using a tape measure. If your eye, on the inside, can see a wide range of angles from the outside, a person on the outside can only see a small range of angles from the inside. However, the same process also works in reverse, and that's why the peephole makes it difficult for people to see into your room. The dorm room door peep holes show the rooms as visible and magnified. This also has the effect of concentrating the light from a large area on the outside into a small area on the inside, thus increasing the intensity (power per unit area), thus making the image brighter. They magnify the hallways when looking out from the room, but viewing the room. The lens is mounted such that it gathers light rays from all angles on the outside of the door, and focuses them on a small pupil-sized region on the inside of the door, so that you (being on the inside) can see whatever is on the outside, through a wide range of angles. This diagram should give you a rough idea (although this is certainly not exactly accurate to reality maybe I'll do a better one later): This is a lens that, in one direction, takes a very wide field of view (up to a full half-sphere) and focuses it into a small area. I'm not an expert in peepholes specifically, but as far as I know, there are a couple of factors that give a peephole its peculiar properties.įirst, according to Wikipedia, the hole is fitted with a fisheye lens.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |