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HANDBOOK OF PHOTOGRAPHY 



Figure 7 is a complete iris-diaphragm assembly with 12 leaves to provide openings 

 that are almost complete circles. This drawing shows the number of parts involved 

 and gives an idea of the small space within which they can be fitted. This is an 

 important point because the available space between the lenses in modern photo- 

 graphic objectives is very limited. In small short-focus lenses there is often only 

 3^2 in. of space for diaphragm leaves. 



Multiblade Shutters. — About 1900, single-blade shutters were found to be inade- 

 quate. Photography had to find means of "stopping" faster motion. Double- 

 blade shutters, as shown in Fig. 8, were the first answer to this demand. A, B, and C 



Fig. 8A. — FPK Automatic shutter made by Bausch & Lomb (from W. O. Hammer) 

 1, release lever; 2, pump for bulb release; 5, exposure indicator; 7, diaphragm adjustment 

 and indicating lever; 8, lever operating blades; 9, levers operating for bulb and time 

 exposure. 



1 5 3 



Fig. 8J5. — Automatic shutter made by Bausch & Lomb (from W. O. Hammer). 1, 

 release lever; 2, pump for bulb release; 3, pump for retarding device; 5, diaphragm indicator 

 and adjusting cam; 7, diaphragm lever; 8, diaphragm leaves; 9, blades. 



