382 



PHOTOGRAPHY AND PROJECTION 



[CM. X 



A Set screw holding the rod (5) in any de- 

 sired position. 



P Q Set screws by which the bellows are 

 held in place. 



B Stand with tripod base in which the sup- 

 porting rod (S) is held. This rod is now grad- 

 uated in centimeters and is a ready means of de- 

 termining the length of the camera. 



M Mirror of the microscope. 



L The sleeve serving to make a light-tight 

 connection between the camera and microscope. 



O The lower end of the camera. 



R The upper end of the camera where the 

 focusing screen and plate holder are situated. 



The plate holder is then put in po- 

 sition, and the dark slide removed. 

 The red glass is then removed for the 

 short time necessary for the exposure 

 O/i oth sec., more or less) and then re- 

 placed. The dark slide is put back in 

 the holder. The plate is developed and 

 printed as usual. 



When working with dry plates in this 

 way great care is required to avoid stray 

 light. Stray light which would not in- 

 jure printing papers will fog a dry plate. 



544. Using a camera and plate 

 holder. When exact results are required 

 or much photo-micrography is to be undertaken, it is better to use 

 a camera in connection with the projection apparatus (fig. 219). 



The camera and projection apparatus are put on a long labora- 

 tory table, or the camera may be put on a second table and adjusted 

 to the height of the projection microscope. The camera is con- 

 nected with the projection microscope by means of a light-excluding 

 sleeve such as that used by Zeiss with his photo-micrographic 

 outfit (fig. 217-218). 



The camera serves to exclude all stray light and to hold the 

 plate holder in the correct position. The camera is supplied with a 

 focusing screen which occupies exactly the same position as doe& 

 the plate during exposure. 



FIG. 217. VERTICAL PHOTO- 

 MICROGRAPHIC CAMERA. 

 (From Zeiss' Photo-micro- 

 graphic Catalogue). 



