. The book of photography; practical, theoretical and applied. spot lens is simply a plano-convex lens,upon which is painted a circle with blackvarnish, which prevents the central raysreaching the objective. But by far thebest dark-ground illumination is obtainedby means of the paraboloid (Fig. 7lo), alens hollowed in the front, and in whichis fixed a curved piece of blackenedmetal, which may be raised or lowered Iig. 70S.—SwiftsApochromaticCondenser. Fig. 70!).— iiiiipilpiw condenser to the objective. The con-densers are provided with interchangeablediaphragm
. The book of photography; practical, theoretical and applied. spot lens is simply a plano-convex lens,upon which is painted a circle with blackvarnish, which prevents the central raysreaching the objective. But by far thebest dark-ground illumination is obtainedby means of the paraboloid (Fig. 7lo), alens hollowed in the front, and in whichis fixed a curved piece of blackenedmetal, which may be raised or lowered Iig. 70S.—SwiftsApochromaticCondenser. Fig. 70!).— iiiiipilpiw condenser to the objective. The con-densers are provided with interchangeablediaphragms of various sizes for use with
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphotography, bookyear
