Ordinarily the appended table is a good one to follow in the use of the stops with a rapid reCtilinear lens, but there are some exceptions : No. 4.—For instantaneous exposures in sh,Vhily cloudy weather and for portraits. Do not attempt instantaneous exposures on dark, cloudy days.
No. all instantaneous exposures when the sun shines.
No. t6.—For instantaneous exposures when the sunlight is unusually strong and there are no heavy shadows ; such as views on the seashore or on the water, or in tropical or semi-tropical climates ; also for interior time exposures.
Nos. 32 and 64.—For interiors. /Vez,er for instantaneous exposures.
No. t2S.—For time exposures outdoors in cloudy weather. Nezier for instantaneous exposures. The time required for time exposures on cloudy days with smallest stop will range from Y, second to 5 seconds, according to the light. The smaller the stop the sharper the pitaure.
To get " depth of focus ", e., have all objects, both near and far, needle sharp, use the smallest stop.
The No. 4 stop is not to be used when absolute sharpness is desired, as the opening is so large that few lenses will have a good " depth of focus " with it—i. e., only the objeCts at the exael distance focused will be sharp, those nearer by or farther away being more or less " out of focus." We find in the instruCtion books for the fixed focus Kodaks having rapid reelilinear lenses that we are told to use the No. 16 stop for ordinary snap shots, while the above table says to use No. S. The reason for this
exception is easily explained, and to avoid confusion and apparent contra dielion, should be given : You have, no doubt, often noticed that many photographs are more fully timed in the center than at the edges and, for instance, that you could mark out a place, say, 31,<, x 3% inches in the middle of a 5 x 7 photograph that would be fully dined, while the outer edges were considerably under-timed. Now the lenses on the 3=,< x Bulls-Eye Kodaks will in reality cover a 5 x 7 plate with the No. 16 opening, and so by using only the central portion where the greatest illumination occurs, we find it practical to make snap shots with this small opening.
Sharpness is extremely desirable in a picture, but 1,vhat we call "round ness " and " atmosphere " is perhaps fully as important. \Vhat is meant by these rather vague terms is sometimes puzzling to the beginner and they are, perhaps, best explained as referring to that quality in a picture which gives the proper idea of both distance and perspe6tive—that quality which is the opposite of the silhouette ; which makes every objeCt appear in proper relation to every other objea and gives life and chara6ter to the piCture. "Atmosphere " and " roundness " we find by pra6tical experience are somewhat lost by using too small a stop. We should, therefore, use the largest opening which will give us a sharp pielure.