ADAPTING A KODAK FOR WORK IN THE FIELD 159 



the two additional lenses, one at a time, the focus of the combina- 

 tion is further reduced, as shown in Scales III and IV of Figure i. 

 With the three used successively, the entire range of object-distance 

 from infinity to less than eight inches can be accommodated, using 

 only the two inches adjacent to the bellows-limit for adjustment. 

 After obtaining the lenses, the several combinations were cali- 

 brated for diflerent distances b}" focusing on a ground glass placed in 

 the image-plane and the readings made on a white celluloid metric 





Fig. I. — Diagram showing four focusing scales in relation to the image-plane 

 and beUows-limit as follows: Scale I, with kodak lens of 6.75-inch focus; Scale II, 

 using 52-inch focus auxiliary lens; Scale III, using 16-inch focus auxiliary lens; 

 Scale IV, using 8-inch focus auxiliary lens. The figures at the right show the foci 

 of the several combinations and the diagram shows clearly the increase in scope of 

 the bellows as the auxiliaries of shorter focus are added. 



scale which was attached to the bed, as shown in Figure 2. From 

 these data were constructed the tables I and II which were photo- 

 reduced and pasted in place on the bed of the kodak as shown. 

 Here they are out of the way, but always convenient. Table I 

 shows the setting on the metric scale for different object-distances^ 

 the three parts of the table referring, respectively, to the three aux- 

 iliary lenses, I, II, and HI. Table II gives the object-distances 

 for different ratios of object to image. For example, suppose one 



