Snelling, Henry Hunt, 1816-1897 · [New York : W.B. Smith] · leaf 80
eaperture; but its inteusity and clearnessbecame necessarily feebler in proportion asthe power which received the image, wasdrawn back from the point of emanation.By reason of not being able to enlarge theaperture without giving place immediatelyto a confused image, the necessity wasvery soon… … same time a clearness, which (varying with,the object-glasses) was recognised, at themaximum, at a distance equal to the focaldistance. With lenses formed of a single piece ofglass, the clearness of the picture was notperfect, the very luminous portions appear-ed bordered with light ; the…
Photography · Art and photography
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