Snelling, Henry Hunt, 1816-1897 · [New York : W.B. Smith] · leaf 355
will be seen from the accompanying wood-cut, consists merely of segments of a cir- cle, numbered and placed at fixed distancesapart, upon a moveable axis. This is co-pied by the camera on a plate or paper,and the result is shown in the annexed fig-ure (50), in which it will be seen different … 50 degrees of effect are supposed to have beenproduced. These determine the best focalpoint for any lens very readily, and it is 1852. The Photographic Art-Journal. 347 really a most useful piece of apparatus inthe hands of the photographer. THE DYNACTINOMETER. The dynactinometer is thus described…
Photography · Art and photography
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![An illustration from [Electric engineering.] (1902)](https://img.insideoutlibrary.com/img/200/ia-electricengineer01inte-169-69.webp)
