PHOTOGRAPHY AND PHOTOMICROGRAPHY. 



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obtained from Bausch & Loinb, who are under contract to manufacture them 

 according- to the Zeiss formuke. In buying a photographic outfit it is economy to 

 get one of the high-priced lenses. It is frequently stated, by those who do not 

 know, that "just as good results" can be obtained with cheap lenses, but one may 

 easily satisfy himself that such is not the case by photographing buildings on a 



Fig. 121.* 



street or any object having many vertical parallel lines and other lines crossino- at 

 right angles. The pictures made by the cheap lenses generally show serious distor- 

 tions. In buying a lens one should know in advance exactly what he wishes to do 

 with it, otherwise he may be greatly disappointed. If he wishes to photograph only 



*FiG. 121. — Newer form of Zeiss-Abbe drawing- camera. The camera is clamped at K by means 

 of S. The prism within R is centered over the eye-piece by screw movements of L and Z. When 

 not in use the prism is swung to the right, as indicated by the dotted lines. The mirror A throws 

 down the prismatic image to the drawing paper. The amount of light is governed by the substage 

 iris-diaphragm and by rotating B and R, which contain smoky glasses of graded densities. P is 

 an extra prism. The image on the paper will also be clearer if it is placed in shadow by means of 

 a screen of some sort. 



