The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Table of Exposures for Enlarging. By E. Ferrero.
As an illustration of the use of the above table, let it be supposed that the lens is stopped down to The actinometer is placed
close to the negative, and the time required for the registration of the standard tint is noted. Let it be supposed that the time is fifty seconds. The number 50 must be found in the first column of the table, and by running the eye along the horizontal row of numbers until we come to the column headedit will be found that the
exposure is three minutes.
The table shows the exposures to be given to Eastman's and Britannia slow bromide papers, according to the actual intensity ratio of the lens, and to the actinic power of light as measured by Stanley's actinometer. Britannia rapid bromide paper requires one-fiftieth of the exposure indicated, and gelatino-bromide plates of ordinary rapidity one-fifteenth to one-twentieth.
Full directions for developing, clearing, fixing, etc., will be found included under Bromide Paper (g.v.).
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