50. Ascertaining The Exposure

Ascertaining The Exposure. Cover your head and camera with the focusing cloth, to exclude all light from the ground-glass excepting that which comes through the lens. Open the lens to the largest aperture and then remain under the cloth until the eyes become accustomed to the darkness, so you can see the image distinctly over the whole of the ground-glass screen. It is important that the eyes become perfectly accustomed to this light before making any attempt at judging the exposure. Therefore, without uncovering the head, with one hand placed upon the stops or diaphragm, stop down the lens by degrees until the plate is sharply focused. At this stage observe the strength of illumination on the ground-glass, as this will serve as a guide to determine the exposure necessary. Better over than under-expose. In fact one should aim to expose fully. Bear in mind that where a long exposure is required, 40 seconds is only twice as much exposure as 20 seconds, and the giving of 30 seconds exposure would not materially cause over-exposure, if 20 seconds was the correct time to give.

Exposure Table for Interiors.

51. This table is based upon the use of a stop not smaller than f. 16 or U. S. 16. Where the next size smaller stop is used, two times the exposure must be given, so calculate accordingly. The plate used is the ordinary fast plate.

52. White Walls And More Than One Window

White Walls And More Than One Window. Bright sunlight outside, 8 seconds; hazy sun, 20 seconds; cloudy bright, 40 seconds; cloudy dull, 1 minute and 20 seconds.

53. White Walls And Only One Window

White Walls And Only One Window. Bright sun outside, 12 seconds; hazy sun, 32 seconds; cloudy bright, 60 seconds; cloudy dull, 2 minutes.

54. Medium Color Walls And Hangings And More Than One Window

Medium Color Walls And Hangings And More Than One Window. Bright sun outside, 16 seconds; hazy sun, 40 seconds; cloudy bright, 80 seconds; cloudy dull, 2 minutes and 40 seconds.

55. Medium Color Walls And Hangings And Only One Window

Medium Color Walls And Hangings And Only One Window. Bright sun outside, 24 seconds; hazy sun, 60 seconds; cloudy bright, 2 minutes; cloudy dull, 4 minutes.

56. Dark Colored Walls And Hangings And More Than One Window

Dark Colored Walls And Hangings And More Than One Window. Bright sun outside, 40 seconds; hazy sun, 1 minute and 20 seconds; cloudy bright, 2 minutes and 40 seconds; cloudy dull, 5 minutes and 20 seconds.

57. Dark Colored Walls And Hangings With But One Window

Dark Colored Walls And Hangings With But One Window. Bright sun outside, 1 minute and 20 seconds; hazy sun, 2 minutes and 40 seconds; cloudy bright, 5 minutes and 20 seconds; cloudy dull, 10 minutes and 40 seconds.

58. This table is intended for rooms with windows receiving the direct light from the sky, but not with the sun shining on the windows. Time of day, from three hours after sunrise until three hours before sunset. If earlier or later the time required will be longer.