The Photographic Reflecting Power of Colored Objects

Loyd A. Jones

In A previous communication1 the use of panchromatic negative film for motion picture work was discussed at some length, and the many advantages arising from the use of this material in the reproduction of scenes consisting of collections of variously colored objects was emphasized. In a later communication2 the subject of characteristics of light filters and methods of using them to obtain any desired rendering of colored objects was treated. In these papers attention was directed chiefly to the exposition of fundamental laws and theoretical relationships which determined the quality of tone reproduction obtained when a series of colored objects is rendered by a photographic process as a series of brightness values entirely lacking in differentiated hue and saturation factors. Reasoning from these established relationships, certain qualitative conclusions relative to the photographic rendition of colored objects were drawn, but no data of a quantitative character relative to the subject were given. For instance, it is evident from a consideration of the spectral sensitivity of photographic materials and the spectral sensibility (visibility) of the eye that while a red object may have a very high visual brightness and hence be equivalent visually to a gray near the white end of gray scale, this same red object when rendered by means of ortho-chromatic film will have a low photographic brightness and hence will be rendered in the photographic reproduction near the black end of the tonal scale. Likewise, from a consideration of the spectral sensitivity of panchromatic film, it is apparent that this same red object when rendered by means of panchromatic film should have a much higher photographic brightness and therefore lie nearer to the white end of the gray scale and hence be rendered more nearly as it is seen visually. From the data already given relative to the spectral sensitivity of photographic materials, quality of light, and reflection characteristics of colored objects, it is possible to draw many such qualitative conclusions.

Print ISSN
Published
1927-09
Content type
Original Research
DOI
10.5594/J06597