The Camera and its Accessories 7 



of this I will speak later in connection with the Graflex 

 camera. I use the Iris Diaphragm Shutter for waiit 

 of a better one. There are others, such as the Sector 

 and Volute. These three are probably among the 

 best shutters; but even these' are not by any means 

 ■perfect. The one with the greatest speed is so deli- 

 cate in its construction that it is not to be depended 

 •upon. The so-called uniform and reliable action of 

 these shutters is not always trustworthy. One of 

 the principal difficulties with the Iris Diaphragm 

 Shutter is that the greatest efficiency of the light can- 

 not be utilized, on account of the mechanical cbnstruc- 

 -tion of the shutter. This . is probably true of most 

 .shutters whose openings are controlled by "leaves." 

 The smaller the opening in the diaphragm, the longer 

 ■ will be the exposure; but to compensate for this, 

 • there is an increase in depth of focus, and greater 

 covering capacity of the lens. Such numbers as 

 F 4, F 8, F 16, and F 32 mean, practically, that if 

 the right exposure with a certain light for.F 8 is one 

 second, F 16 will require two seconds; and F 32 four 

 seconds. In general, the smaller, the' opening in the 

 diaphragin, the sharper will be the negative;, but the 

 really artistic effects can only, be produced by the 

 larger openings which impart to the picture a softness 

 very pleasing to the eye. 



