As humans we have certain limitations due to the way that we are born. Certain aspects of our bodies affect the way that we can or cannot preform. We can not run as fast as a cheetah can, we cannot see in the dark, we don't have poisonous skin to protect ourselves, and do not have fur to keep us warm. However, to compensate for our weakness we have built tools in which we could do all this things one way or another. The Optical Lens is our answer to compensate for our poor eyesight thus providing clearer sight.
What is a Lens?
Lens
–noun
1. a piece of transparent substance, usually glass, having two opposite surfaces either both curved or one curved and one plane, used in an optical device in changing the convergence of light rays, as for magnification, or in correcting defects of vision. (Dictionary.com)
Lens and Light
A Lens is basically a way to concentrate beams of light to come together at a certain point. The way that vision works is by light rays hitting certain objects with a certain frequency that reflect that certain frequency, hit our eyes, converges then is registered by out brains. Lenses work in the same way that the lens in our own eyes work. With a certain concave of a lens the angle at which the light beams converge changes the range and distance that we are able to view things in focus. As all light waves are directional, the way that we view light changes depending on what type of material and the intensity. In the case of lenses it depends on the material and the point at which the light converges and bends. When a lens hits the material which is usually transparent, the angle at which the light bends and converges depends on the shape of the material itself. The angle at which the light comes off the subject, goes through the lens, and converges is stationary and the way that the image is shown depends on the distance between the subject and the lens but the converging point stays the same.
Focus
Focus depends on the distance that the media you want the image projected on moves away from the point at which the light converges. The more distance away from the point of convergence the more un focused the image becomes. On camera or camcorders the reason that images sometimes become blurry is because of the fact that the distance between the lense and the film media may be outside of the point of convergence. However depending on the situation of what you want to be in focus depends on what type of lense that you use.
Different Types of Lenses
Not all lenses are created to converge light. Depending on the shape lenses can distort light or even seperate light.
For instance a bi concave or a bi plano lens is able to change the angle at which the light bends. So instead of converging the light it seperates the light, because of the effect that the lens has on the light these lenses are called diverging lenses. The lens that converges the light is called simply as the converging lens. No converging lens is perfect in focusing light it takes meticulous shaping to take out the impuritys. These impurities in the lens can actually degrad the quality of the image itself, making things out of focus and blurring the image. This blurring is called aberrations or spherical aberrations, simply put all the rays lights do not converge perfectly into a point but converge away from the focal point.
Other lenses can be used to increase the point at which certain images or areas are in focus. A Telephoto lens increase the focal length allowing to capture images that for a normal telephoto lens is to far to focus, this is also could also be informally know as magnification of an image, making it possible to focus on objects that are farther then the focal length allows. A Wideangle lens has a shorter focal length than that of the normal telescopic lens thus creates a wider image than that a typical lens would allow. A fish eye lens is also another type of wide angle lens however the way that light converges distorts the image in a sphereical fashion thus creating the image as if it were wrapped around a shere. The Macro or Micro view lens allows for close focused magnification. This is good for detailed images of anything small similar to a microscope.
There are many different lenses for whatever quality image you are looking for. For whatever subject you are looking for with whatever effect you want there is a lens that is specifically made for those functions its only a matter of looking.
