Chemically prepared or sensitized material

Chemically prepared or sensitized material INTRODUCTION OF PHOTOGRAPHY Photography is defined as the science and art of producing an exact impression of an object on chemically prepared or sensitized material by using light. It depends on the sensitiveness of silver compound to light. The photographs are usually taken by means of a photographic camera. Camera is an instrument consisting of a light-tight box with a place for the light sensitive film at one end and covering lens or a combination of lenses by which a real, inverted and diminished image can be obtained on the other hand. This instrument called camera is so devised that lens may be moved forward and backward by screw arrangement, with a view to getting a distinct and clear image of an object, placed before the lens, on the film. While it is easy to make comparisons between the pupil of the eye and the f-stop of a camera or between the retina of the eye and photographic film .Once we get past the basic similarities of the optics of the two systems comparisons begi n to rapidly break down. The eye is not only much more complex than a camera and its film but the two imaging devices function by different chemical mechanisms. The photographer the automatic exposure system of the camera regulates the f-stop opening and time of exposure of her camera to match the sensitivity of film while the iris and retina sensitivity of the eye adjust to correspond to the light level of the scene. This first installment on the chemistry of photography is intended to introduce in a simplified way the basic concepts of silver halide photography. It will not delve into the physics of optics the functioning of cameras and lenses, photographic techniques, non-silver processes, or the artistic aspects of photography. Photography encompasses many things – there is a science to photography, but as a means of expression, it is ultimately an art form. There are many techniques and forms of photography which fill many books in the library and many pages on the Inter net. Beyond this point, the actual taking of pictures, style, and good composition will not be mentioned again. Chemistry is an even larger subject area, encompassing all areas of life and invisible details that are often mind boggling. To couple photography and chemistry is narrower than either subject on its own, but still includes a lot of material. These pages will look at some basics, presenting only a small fraction of the information relevant to the chemistry of photography. Photography encompasses many things – there is a science to photography, but as a means of expression, it is ultimately an art form. There are many techniques and forms of photography which fill many books in the library and many pages on the Internet. Beyond this point, the actual taking of pictures, style, and good composition will not be mentioned again. Chemistry is an even larger subject area, encompassing all areas of life and invisible details that are often mind boggling. To couple photogra phy and chemistry is narrower than either subject on its own, but still includes a lot of material. These pages will look at some basics, presenting only a small fraction of the information relevant to the chemistry of photography.