62 



ELEMENTARY PHOTO-MICROGRAPHY. 



a picture can be obtained, a considerable loss must 

 ensue with wrong adjustments. 



This will be made clear from diagrams (figs. 

 19 and 20). 



When the condenser is stopped down by the iris 

 diaphragm, or otherwise made to correspond with 

 the aperture of objective used, and both condenser 



FIG. 19. FIG. 20. 



Objective and condenser correctly Condenser not focussed 

 focussed and centred. and not centred. 



O G, Objective. S, Slide. C, Condenser. 



and objective are focussed on the object itself, the 

 best possible definition and illumination will be got. 

 But "when the condenser is out of centre and out 

 of focus, the rays of light will be dispersed use- 

 lessly, as seen in fig. 20. 



Some negatives that yield prints on a light 

 ground may also be used for printing with a black 



