PHOTOGRAPHY BY POLARIZED LIGHT— McFARLANE 233 



TECHNICAL DETAILS 



The most suitable negative materials for use with Pola-screens are 

 the panchromatic materials now in general use. Although it is pos- 

 sible to use orthochromatic or even noncolor-sensitizcd materials, the 

 exposure increase is greater. 



The Pola-screen for lens use must be screened from all extraneous 

 light by the proper lens hood. 



The screens supplied for light source use are not suitable optically 

 for use over a lens. Neither can the Pola-screen for lens use be ap- 

 plied to hghts. 



WHAT CAN BE DONE WITH EASTMAN POLA-SCREENS 



A. Pola-screen (type I or I A) at the lens only. Exposure increase required, four 



times. 



L Photographing obliquely through glass or water. 



2. Subduing oblique reflections wliich hide surface detail. 



3. Subduing bright oblique reflections wliich interfere with good composi- 



tion. This oblique reflection control does not apply to metallic 

 surfaces, unless Pola-screens are used over both lens and lights. 



4. Darkening a blue sky when photographing at right angles to the sun. 



The monochrome rendering of the subject photographed is not 

 affected. 



5. The Pola-screen type I A can be used to darken a blue sky when 



photographing in natural color, as with Kodachrome. 



B. Pola-screens (types I and II) at both lens and lights. Exposure increase re- 



quired, 16 times and up. 



1. Copying rough prints, matte prints, damaged prints, and oil paintings 



which show strong reflections due to cracks, canvas texture, or brush 

 marks. 



2. Copying any subject with the lights undiflfused and quite close to the 



camera. 



3. Subduing the reflections in many studio subjects, whether or not these 



reflections are oblique. 



4. Creating unusual lighting and background effects. 



The novelty of this subject makes it difficult to say just what ap- 

 plication will be most valuable. It is, however, a new tool, by which 

 new effects may be achieved, and its hmits are imposed only by the 

 imagination of the user. It is opening our eyes and our cameras to 

 some of the unseen beauties of nature. 



