In recent years, as great progress has been made in the technology of photographic light-sensitive materials for photographing, many high sensitive light-sensitive materials have become commercially available. The expansion of photographing application has been made by using such high sensitive light-sensitive materials for photographing in a dark room without using a strobe, or sports photography with a telephoto lens at a high shutter speed.
Furthermore, cameras, particularly single-lens reflex cameras, having an automatic exposure function have recently become widely used. These cameras have a mechanism in which the light reflected by the film surface upon exposure is received by a light receiving element, which in turn integrates the reflected light into data which are then fed back to determine the shutter time or the amount of light emitted by the strobe.
However, high sensitive color negative films so far developed, e.g., ISO 400 color negative film, are disadvantageous in that they have a higher reflectance on the film surface (emulsion surface side) than an ISO 100 color negative film, causing an increase in the amount of light received by the light receiving element in the automatic exposure meter in the camera, which leads to substantial under-exposure. ISO 400 high sensitive color negative films which are now commercially available have a spectral reflectance of 35% or more at a wavelength of 600 nm on the film surface (emulsion side).
USPTO Backgrounds
USPTO Backgrounds