The Camera and its Accessories 2 
of this I will speak later in connection with the Graflex 
camera. I use the Iris Diaphragm Shutter for want 
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 construc- 
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 
Fos, vo, 210; and F329. 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 
diaphragm, 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. 
