248 



HANDBOOK OF PHOTOGRAPHY 



Table XXIV. — Basic Exposure for Color Motion-picture Photography, 



Photoflood Lamps 

 (Weston Ratings — 10 to 20) 



Table XXIV gives suggested exposure for color motion-picture photography using photoflood 

 illumination. The table is calculated for the following conditions: 



1. Film Speeds. — Based on films having a tungsten rating of Weston 10 to 20. For conversion for 

 films having other speed ratings, 



multiply /-number by 0.35 for Weston speeds between 0.6 and 1.2 



2. Lamps. — It is assumed that only one lamp is used in each reflector. If n lamps are used at the 

 same distance from the subject, divide the apertures (/-numbers) given by y/n- 



condition for which the exposure is to be made, are usually more convenient and 

 flexible than tables. The use of such slide-rule or circular calculators requires, as do 

 also the tables which have been given, that the photographer estimate the light condi- 

 tions for each particular case. This necessity, of course, introduces possible errors 

 due to mistakes or errors of judgment. But tests indicate that the errors from this 

 cause are smaller than might be expected and that the proper use of calculators enables 

 even inexperienced persons to obtain well-exposed negatives. 



Many types of exposure calculators are on the market and may usually be pur- 

 chased for about 10 to 50 cents. Some of the calculators are quite elaborate and com- 

 pUcated; the simpler types are, perhaps, more useful for the beginner. 



