234 



HANDBOOK OF PHOTOGRAPHY 



Table X. — Basic Exposures for Black-and-white Still Photography, 



Indoors: Daylight 

 (Weston Ratings— 10 to 20) 



Table X gives the recommended exposure for indoor subjects lighted by daylight. Because indoor 

 photography is subject to widely differing light conditions, some judgment will have to be exercised in 

 using this table. 



1. Light Values. — The table is based on light values of unity (1) as given in Table IX. If other 

 conditions apply, the exposure time given in Table X should be multiplied by the factors in Table IX 

 which are appropriate. Table X applies to conditions where the room being photographed has free 

 access to full daylight. If tall buildings in the immediate surroundings block off much of the daylight, 

 the exposure times given may have to be increased considerably. 



2. Film Speed. — Table X is based on film speeds having a daylight rating of Weston 10 to 20. For 

 other film speeds, exposure time is inversely proportional to the Weston rating. 



3. Time of Day. — The time of day for which Table X applies is to within 1 hr. of sunrise and sunset 

 for panchromatic material or to within 2H hr. of sunrise and sunset for orthochromatic materials if the 

 room has free access to full daylight. If tall buildings cut off available daylight, the exposures may have 

 to be increased considerably during the early morning or late afternoon. 



4. Aperture. — Exposures for four standard apertures are given. For converting to other apertures 

 see Eq. (23). 



