The American annual of photography . E H4min. 4min. Figure 3. Developed Graded Strips Showing the Difference in Behaviour Between Elon and Hydroquinone. ible on the hydroquinone strip, but at the end of 4 minutesboth strips looked almost alike. When using developers of the Elon type, if the image isexamined by inspection, the photographer is apt to remove thefilm from the developer too soon, because he is misled by therapid appearance of the image, though from the above it isseen that to secure the same density contrast, it is necessaryto develop for almost the same time. We say, therefore, th
The American annual of photography . E H4min. 4min. Figure 3. Developed Graded Strips Showing the Difference in Behaviour Between Elon and Hydroquinone. ible on the hydroquinone strip, but at the end of 4 minutesboth strips looked almost alike. When using developers of the Elon type, if the image isexamined by inspection, the photographer is apt to remove thefilm from the developer too soon, because he is misled by therapid appearance of the image, though from the above it isseen that to secure the same density contrast, it is necessaryto develop for almost the same time. We say, therefore, thatElon has a high development factor and hydroquinone a low 194. HH 195 one, the development factor, or Watkins factor, being equalto the total time of development divided by the time of ap-pearance of the image. When comparing two developer samples, say hydroquinone,by testing developers prepared from them according to thesame formula, the time of appearance of the image is inverselyproportional to the percentage of pure developing agent in thesamples. With other developers it is a rough measure of thedetail rendering power; that is, if the image flashes up quicklyand the negative is not over-exposed, then we are reasonablysure that all the shadow tones will be developed out. (b). The Rate of Development after the Image Appears. Development consists in reducing the exposed grains ofsilver bromide contained in the emulsion to metallic silver. Allthe grains do not commence to develop at the same time, be-cause they are distributed throughout a more or less thicklayer of gelatine, but the rate at which the grains developas a whole depends on the numb
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishernewyo, bookyear1922
