CH. 



PHO TO-M1 CROC R API! > 



229 



For a horizontal camera it is frequently better to swing the 

 mirror entirely out of the way and allow the light to enter the con- 

 denser directly or after traversing the bull's eye (Fig. 174). 

 If the object is small an achromatic combination like a Steinheil 

 magnifier or an engraving glass is excellent (Fig. 175). When the 

 light is satisfactory as seen through an ordinary ocular, remove the 

 ocular. 



(A) Photographing without an Ocular. After the removal of 

 the ocular put in the end of the tube a lining of black velvet to 

 avoid reflections. Connect the microscope with the camera, making 

 a light-tight joint and focus the image on the focusing screen. One 

 may make a light-tight connection by the use of black velveteen or 

 more conveniently by the Zeiss' double metal hood which slips over 

 the end of the tube of the microscope, and into which fits a metal 

 cylinder on the lower end of the camera (Figs. 170, 176). In 

 the first figure the connection has been made. 



FIG. 177. Zeiss' Achromatic Con- 

 denser, c. s. c. s. Centering screwsfor 

 changing the position of the condenser 

 and making its axis continuous with 

 that of the microscope. A segment 

 of the condenser is cut away to show 

 the combinations of lenses. For very 

 low powers the upper lens is some- 

 times screened off. There is an iris 

 diaphragm between the middle and 

 lower combinations. (Zeiss' Catalog.} 



,Ex c 



Exc 



A B F G 



FIG. 178. A. Shows that the condenser is not centered. B. That it is 

 centered. {D-D} Image of diaphragm formed by condenser, 



F. G. Shows that the flame (F I) illuminating the condenser is not cen- 

 tral. In that case the lamp or the mirror must be changed in position until 

 the image of the flame is exactly central. (See also \ 92-93.} 



