File:The American annual of photography (1922) (14758695156).jpg

Identifier: americanannualof36newy (find matches)
Title: The American annual of photography
Year: 1922 (1920s)
Authors:
Subjects: Photography
Publisher: New York : Tennant and Ward
Contributing Library: Harold B. Lee Library
Digitizing Sponsor: Brigham Young University

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o to 3 c u ■M a> & < o oo When the window faces the sky, or has an open expanse infront, it is often better to cover the aperture with fine ground-glass or tracing paper, omitting the reflector. The negativeshould not be too close to the diffusing medium, or the grainmay be focused. With an enlarging lantern having a compound plano-convex condenser it is a much more complicated matter toget even lighting. The brightest part of the arc, incandescentfilament, mantle, or lamp flame, as the case may be, has tobe brought on to the common axis of the condenser and
Text Appearing After Image:
Figure i. objective, and adjusted at just the right distance from thecondenser, which varies with the amount of enlargement.Theoretically, the conditions are as illustrated by Figure 2,where it will be seen that the illuminant A is placed at sucha distance from the condenser BC as to converge the beamof light into the center of the objective D; while, at the sametime, the objective itself is in such a position with respect tothe negative E as to project a sharply-focused image of thedesired size on to the easel F. Ignoring, for simplicity, the exact nodal points, this meansthat the distances AB and CD are conjugate foci of the 160 condenser, while the distances ED and DF are conjugate fociof the objective. In practice, however, such an adjustmenthas to be deviated from, owing largely to the condenser beingpoorly corrected and having no precise focus. The bestlighting is found to be obtained when, the negative havingbeen removed, an image of the light-source is formed on awhite card te

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