CHAPTER VI 



THE PHOTO-MICROGRAPHIC CAMERA 



Simple Forms of Vertical Camera. Having considered the opti- 

 cal part of the apparatus in the earlier chapters, reference must 

 now be made to that portion which is more particularly of a 

 photographic character. Essentially this consists only of an 

 ordinary photographic camera, and it will probably happen that 

 the majority of workers who are starting from the beginning 

 will at least make some attempt to obtain photo-micrographs 

 with such a camera used in conjunction with a suitable micro- 

 scope. Under these conditions, all that is required is that the 

 microscope shall be set on some form of firm table or bench, 

 and that the camera, of course with the ordinary photographic 

 lens removed, shall be so placed that the microscopic image 

 is projected directly on to the ground- glass focussing-screen. 



Under such circumstances the only points that require 

 careful attention are, firstly, that the camera should be placed 

 with the centre of the focussing-screen in alignment with 

 the optical centre of the microscope, and, secondly, that the 

 focussing-screen should be exactly at right angles to the optical 

 axis. 



It is evident, however, that such an arrangement is open to 

 considerable objections, since, although it may by its aid be 

 quite possible to obtain good photographs when using low 

 powers, it becomes a matter of considerable difficulty if the 

 magnification exceeds some twenty or thirty diameters ; for 

 there is no arrangement to ensure that the relative position 

 of the microscope and camera is not altered during the 

 process of focussing and exposing. 



Nearly all who take up this work at some time or another 



in 



