SHUTTERS 



103 



are different makes of shutters of this period. The blades are clearly shown — in the 

 closed position in 8A and 8C, in the open position in Fig. 8B. Although these shutters 

 were a great advance over previous models and were used all over the world on 

 American-made cameras, they were merely one step in a long series of development. 

 As increasing speed and accuracy became necessary, a different type of blade action 

 was devised. 



Figure 10 shows a three-blade shutter with blades 2 and 3 removed. In this 

 illustration, 5 is a blade which is operated by rotation of the ring 8 through pressure 



Fig. 145. — Retarding device of the Compur shutter (JuUus Springer). /, shutter 

 set for slowest speeds to 3^{o sec. ; II, shutter set for medium speeds from J-'fo to 3"ioo sec; 

 ///, shutter set for fastest speeds. 



The labeled parts are as follows: a, speed-indicating dial; b, fixed plate support for cam; 

 c, pivot for dial and cam; d, e, speed-control cams working together; /, pin connecting the 

 cams with dial a; g, h, pins regulating positions of two levers by cams; i, pivot of gear sector 

 s; k, pivot or setting lever p; I, pivot of retard lever t; 711,1%, escapement mechanism which 

 is thrown out of action at speeds of I-iq sec. and faster; o, pivot of escapment lever v; 

 p, setting lever; r, gear retard, acting with z and m (these gears do not operate at maximum 

 speed because the gear sector s is depressed to its lowest extent by pin h before lever p 

 is operated); s, gear sector pivoted at i; t, retard lever; z, gear retard. 



on stud 6 which is firmly attached to the blade. Note that only a few degrees of 

 rotation of the ring 8 suffice to open the blade completely and that spring 9 acts to 

 close it by pulling the ring back to position b where it is stopped by stud 10 which is 

 fixed in the case. All this makes for rapid action when the parts are made of light, 

 rigid material. 



These are only typical of the principles of modern shutters because shape and 

 number of blades as well as the method of operating them are all subject to wide 



