MOTION-PICTURE PHOTOGRAPHY 



679 



the composition of both of these positive developers being given in Laboratory 

 Practice. 



DupUcating positives for master prints, like the duplicating negatives previously 

 described, are characterized by high resolving power, fine grain, and wide latitude. 



Unexposed 



Fi/m loop , ^ 

 6aie~ 



Lens—> 



Revolving '' 

 shulier 



In lerchangeable 

 film magazine 



Exposed 



-- Take-up 

 roll 



Tension- 



driven 



core 



~ Guide rollers 

 - -Driving sprockel 



Guide rollers 



^In iermlHeni 



Fig. 225. — Schematic diagram of camera mechanism. 



Fig. 23. — Mechanism of Bell & Howell camera. 



Eastman provides two types, the characteristics of which appear in Fig. 20. 

 The former (No. 1355) begins to flatten out at a gamma of about 1.7, while 

 the latter (No. 1362), which does not reach the same point imtil a gamma 

 of about 2.4 is reached, is suitable for use at very high gammas. DuPont also pro- 



