594 IMAGE FORMATION WITH MOVING PICTURES [Cn. XIV 



slide-carrier and is evenly illuminated by the combined effect of 

 spherical aberration and an extended image of the crater. 



826. Image formation with moving pictures. Let us trace 

 the course of the rays from the condenser to the screen assuming 

 a 







- 333- IMAGE FORMATION OF A MOVING PICTURE FILM WITH AN EXTENDED 



SOURCE OF LIGHT. 



a,b Second element of the condenser. 

 L' Image of the source of light. 

 s, t Film. 

 Objective. 



y, x, z Points on the face of the objective. 

 b' Image of the condenser. 

 /' Image of the film on the screen. 







FIG. 334. IMAGE FORMATION OF THE MOVING PICTURE FILM WHEN USING 

 A POINT SOURCE AND A CONDENSER HAVING SPHERICAL ABERRATION. 

 a, b, c, d, e, f, g Points on the condenser face. 

 r, s, t Film. 

 D Diaphragm in front of the objective. 



the crater image to cover the entire opening of the aperture plate. 

 From every point of the condenser as a, fig. 333, light spreads out 

 over the area s t. Light will reach the point 5, on the film from 

 every part of the condenser between a and b. From 5, light 

 spreads out in every direction between the limiting rays b s w, and 

 a s y, and the objective 0, collects all of this light to the point s' on 

 the screen. Light from s, reaches 5', between the limiting rays 



