258 Cvicintiati Society of Natural Histoiy. 



much as a print, which is examined for a longer time. In fact, 

 too many details detract from the appearance of an nnage on a 

 screen, the principal features of which are alone ot interest. 



Detective cameras using quarter size plates are only good for 

 studies, instantaneous views, and lantern slides. Prints made on 

 such a small size are insignificant; objects and details are .so 

 minute as to be ahnost microsco])ic: furthermore, the perspective 

 suffers very much. Any one can be convinced of this fact by 

 looking through a slide and comparing its perspective with that 

 shown when its image is thrown upon a screen. In fact, a 4x5 

 picture is the smallest admissable that will give details and perspec- 

 tive without tiring the eyesight. .Amateurs making that size exclu 

 sively will find it quite convenient and at the same time quite a 

 luxury, when looking over their pictures, to use a graphoscope 

 magnifying about two diameters. By being magnified a ])icture 

 gains in depth and perspective; shadows be ome trans])arent, and 

 details are observed which otherwise escape the naked eye. 



Concluding, therefore, that 4x5 is the minimum size plate 

 which will produce anything like a fair picture, the maximum size 

 need not exceed 6^x8^, unless the amateur is very ambitious, and 

 if so, after having acquired all the jiaraphernalia accompanying 

 photographic work, he may regret his enthusiasm, and soon have 

 a camera and lens for sale. 



I have said nothing pertaining to portrait work, as it is not 

 within the province of an amateur, who is not prepared for that 

 class of work, and therefore can not do it as well as professionals, 

 who devote a lifetime to it. When portraits are wanted, however, 

 any size plate can be used. By portrait work I refer to such work 

 as done in photograph galleries. 



SELECTION OF LENSES. 



Though there is a great variety of lenses used in photography, 

 the amateur limits himself to two kinds — the single view lens and 

 the rectilinear doublet. The single view lens is corrected for 

 everything except what is called barrel distortion. This distortion 

 is very apparent when long, straight lines are brought into view. 

 .Any straight line not passing through the center of the field of the 

 lens will be carried more or less toward the center of the picture, 

 and this distortion is greatest at the edge of the field. This lens is 

 therefore not good for architectural subjects, or any view in which 

 appear near buildings of large dimensions. It is said, hovvever, 



