130 SCIENCE OF HOME AND COMMUNITY 



As the size is decreased, the time of exposure must be in- 

 creased. 



In what are called snapshots, the stop is set for a short 

 exposure, from -% to ^ of a second. The largest stop should 

 be in position. This kind of exposure is best made on bright 

 days. One motion of the lever opens and closes the shutter. 

 While making the exposure, the camera should be held level 

 and steady. 



In what are commonly called time exposures, the camera 

 must be placed on some solid support like a tripod. The 

 stop may be set at any desired size and the time of exposure 

 arranged accordingly. The brighter the day, the smaller 

 the stop that may be used and the shorter the time of ex- 

 posure in comparison with the same objects on cloudy days. 

 The shutter is so set that it can be held open for any desired 

 time, as determined by a watch. 



The time of these exposures usually varies from % second 

 to 5 seconds, according to the stop used and the brightness 

 of the day. For exposures outdoors the small stop may be 

 used, but a longer time of exposure must be given. The 

 time required for an exposure depends on the time of day 

 and on the kind of day. Anything that causes a change in 

 the intensity of light affects the time of exposure. 



For interior exposures much more time is needed than for 

 outdoor exposures. The time varies according to the time 

 of day, the number of windows in the room, and the color 

 of the walls and hangings. 



Flashlights. By means of flashlight powders, it is possible 

 to obtain pictures in the evening which are nearly as good 

 as those obtained in the day. The flash powders are now 

 sold in the form of sheets, which can be easily lighted. The 

 sheet is pinned to a piece of cardboard and should be placed 

 two or three feet behind the camera and two or three feet 

 to one side. It should be placed at the same height, or a 

 little higher than the camera. Just before the picture is to 



