The beginning about the camera lens
Summary
A lens to use for photography with the photographic lens (photograph lens). With the thing which incorporated plural lenses in a body tube, I am attached to a camera and use it. I say the lens for photographs, but often am usually called merely lens. A diaphragm and focus (focus alignment) mechanism are incorporated in a photographic lens in many cases. The specifications of the lens are referred to at the focus distance a relative aperture (F-number). It is the lens which I can photograph at the shutter speed that is fast if other conditions are the same brightly so that F-number is small. It is classified in a standard lens, a wide-angle lens, a telephoto lens by the focus distance. There are many zoom lenses which can change the focus distance recently. I do not often have focus mechanism with the lens for large size cameras, and a shutter is often incorporated.
Early in the history of the camera, I have used a lens (single lens lens) only for one piece, but light quantity decreases and has a problem that I come to have a long exposure time when I am small (big with F-number) and do a diameter without the image which, in that case, distortion is big, and is sharp being provided to relatively reduce the influence. Therefore, I put the lens of double several pieces together, and there was less distortion, a trial I was sharp and to make the big lens of the diameter has been continued for many years. It was a fixed single focus lens of the focus distance of the lens at first, but the focus distance came to be settled for the variable zoom lens later.
Main classification of the lens
A single focus lens. The thing which the focus distance was fixed to. The contrary concept of a zoom lens changed the focus distance into continually. In comparison with a zoom lens,
* Because the constitution number of sheets of the lens tends few, I am strong in backlight and am small and light.
* It is easy to revise a chromatic aberration, the skewness of the image, a distortion.
* Because it is easy to lower F-number, rich expression by the choice of a wide diaphragm is provided. In addition, is high-speed by opening a diaphragm; can press the shutter.
In the photograph schools, I often study the composition with an at first single focus lens from a thing called (I do not think that I do only angle of view adjustment from one point and adjust an angle to the all around) which I depend on zoom when I enter and do not use the foot for from a zoom lens.