whole time the lens is open, and ordin- ates such as ef, e' the areas of the portions of the lens open at corresponding times, o e, o' e', from the commencement of the exposure. In this diagram the line c T), parallel with o a, indicates the time for which the full opening of the lens aperture was… … opening and closing of the lens. The setting out and calculation of the areas of these diagrams is a matter of considerable diffi- culty in most cases. A dmitting that the effects produced during opening and closing of the lens are equal, the total effect is given by — Effect of shutter = 2/, o<^…
Photography
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