It is specially manufactured to be free of defects and distortion, and to withstand heat and humidity. Each type f optical glass is classified according to its refractive index and light dispersive quality. Two or more types of optical glass are typically used in the component elements of photographic lenses. Optical sensitizing is a method of increasing a films sensitivity by the use of dyes. Optical wedge is a strip of material, clear at one end and gradually increasing in opacity, which is used to determine the effect of light intensities on sensitized materials.
Optics is the science dealing with the behavior of light.
Ordinary emulsion is a term applied to a photographic emulsion which is only sensitive to ultraviolet and blue light. Orthochromatic is used to describe an emulsion which is sensitive to blue and green light, but insensitive to red. Over-development is a term indicating that the amount of development recommended by the manufacturer has been exceeded. It can be caused by prolonged development time or an increase in development temperature, and usually results in an increase in density and contrast. Overexposure is an expression used to indicate that the light sensitive material has been excessively exposed.