File:The American annual of photography (1922) (14758718026).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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n of the developer, andthe time of appearance noticed in each case. The results wereas follows: 1st Sheet loth Sheet 20th Sheet Time of Time of Time of Appearance Pensity Appearance Density Appearance DensityElon ... 5 seconds 2.5 12 seconds 1.5 40 seconds 0.98Sample X 5 seconds 2.2 16 seconds 1.4 56 seconds 0.90 From the above tests it is seen that the sample X comparesfavorably with Elon as regards its photographic behavior al-though the color of the silver image produced was decidedlybluer than that given by Elon. REPORTS ON DEVELOPING FORMULA For practical purposes developing solutions may be dividedinto five classes as follows: 1. Developers for average work. a. Negative developers (tray and tank). b. Paper developers. Tests on these developers should include developing power,life, color of image, fog, etc. 2. Developers for under-exposed negatives. These developers should be tested against the followingformula, which is the best present known formula for under-exposure work: 208
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AUTUMN ASPENS. EDGAR A. COHEN. 209 Metric Avoirdupois Sodium sulphite 60 gms. 2 oz. Elon 16 gms. 250 gr. Hydroquinone 16 gms. 250 gr.. Caustic soda 10 gms. 150 gr. Potassium Bromide 10 gms. 150 gr. Water to i liter 32 oz. Then add Wood or Denatured Alcohol 50 cc. If this developer gives too much contrast, reduce the nega-tive with ammonium persulphate. Preliminary tests should be made on flashed film, giving suchan exposure that a just visible deposit is given by the abovedeveloper, in, say, 3 minutes. If the formula to be tested com-pares favorably with the above, a final test should be givenby cutting a camera exposed film in two and developing one-half in each developer. 3. Contrast Dez^elopers. a. Short life type. b. Long fife type. The best contrast developer known to date is the following i^ Solution A. Metric Avoirdupois Sodium Bisulphite 25 gms. 375 gr. Hydroquinone 25 gms. 375 gr. Potassium Bromide 25 gms. 375 gr. Water to make i liter 32 oz. Solution B. Caustic Soda 45 gms.

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