196 



PHO TO-MICROCRAPHY. 



[CM. VIII. 



should be used. The focusing screen as thus prepared with a clear 

 center, serves both for the general focusing and the finest focusing, and 



the fewer the 



avoids the danger of using a double screen. 

 processes the less the liability to error. 



That 



is, 



Fio. 151. Periqraphic Objective of about go millimeters equivalent focus. foi 

 making photo-micrographs at a magnification 0/2 to / 5 diameters. It was found 

 to give the best results when used right end to as in ordinary photography. (From 

 the Gundlach Optical Co. ) 



Fig. 152. Zeiss' Anas- 

 tiginat Objective of about 

 &5 millimeters equivalent 

 focus for photo-micro- 

 graphs at a magnification 

 of 2 to 75 diameters Ex- 

 cellent results were ob- 

 tained with this, and the 

 other short focused anas- 

 ligmats. On the whole 

 the results were more sat- 

 isfactory when the tens 

 was used right end to as 

 in ordinary photography. 

 {From the Bausch and 

 r.omb Optical Co.) 



§ 337. Development of the Negative.- After the exposure, comes 

 the development ; tins in photo-micrography requires more judgment 



