This being so, we need not for the present concern our selves with " rules of composition," " balance," " light and shade," and the thousand and one artistic considerations which at a later period of our photographic career will pro bably engage our attention.
Very little time, therefore, need be spent in selecting a suitable subject for our first exposure, although, in order that we may derive as much instruction as possible in the proper use of our apparatus, it would be well to include in the view a house or a building of some kind. We will assume, therefore, that some such subject es this is chosen —a country house, with a background of trees and distant hills, the foreground being composed of a garden with a fence in the immediate front. Probably, if we were to allow artistic considerations to weigh, we should prefer to exclude the uninteresting fence, but for our special object, namely, learning the proper use of our apparatus, it will prove helpful rather than otherwise.
The point of view having been selected, we proceed to erect the tripod, taking care, in doing so, to tightly clamp all the screws, and to extend the legs sufficiently apart to give steadiness. The camera may then be taken from tho case, the baseboard let down, and secured by tightening the brass struts at the side, it being finally firmly fixed to the tripod head by means of the brass screw which is provided for the purpose. When the lens has been attached, by screwing it into the flange which should have been fixed to the rising front of the camera, WO shall be ready to make our first exposure. Having removed the lens cap, the reader may throw the focussing cloth over the camera, taking care, of course, not to obscure the lens, and proceed to arrange the picture upon the plate. He will at first probably be able to distinguish nothing but a hazy outline of the subject ; but if he will place his hand upon the focus sing screw, or pinion, at the side of the camera and gently turn it, first towards him, and then away from him, he will find that the image on the ground-glass screen gradually becomes more distinct. Let him now carefully watch one portion of the picture—for instance, the house, which oc cupies what would be called in technical language the middle distance, and carefully turn the pinion until it appears sharply defined and clear. It is assumed that the index on
the ring which adjusts the diameter of iris diaphra,gm has been in the first instance placed opposite the denominator marked f/8, which is the largest opening of the lens. Having focussed the house sharply, he will also observe that both the fence in the foreground and the trees behind the house are, more or less, indistinct and fuzzy. This experiment will show him that a photographic lens is only capable, when used with large stops, of giving sha.rp definition in one plane, for if he readjusts the pinion, and so gets the fence sharp, he will find that the house in turn becomes as fuzzy ELS the fence was previously. If, however, he revolves the ring on the lens mount until the index points to f/9.2, and again examines the image, he will find that each plane of the picture, the fence, the house, the trees, and the distant hills all appear crisply defined, or, in photographic language, in sharp focus. He will also note, that although the definition has been improved, the brightness of the image has considerably diminished. It will thus be easily seen that the function of a stop or diaphragm is twofold, namely, to improve definition, but the same ratio to increase the duration of exposure. The reader will do well to keep to the use of one sized stop in making his exposures until he can with some accuracy de termine the correct time to allow. There is no magic in f/22, or in any other particular sized stop ; but that number will be found to give good general definition without being so small as to necessitate an unduly long exposure.
The cap should now be replaced upon the lens, and the ground-glass frame being folded back upon the top of the camera, the double-back marked " 1 " and " 2 " may be removed from the case (the focussing cloth having been previously wrapped round it), and slid into the groove pro vided for the purpose at the back of the camera, the focus sing cloth being still kept over all, in order to prevent the slightest chance of the plates being affected by light. This having been done, the hand may be placed underneath the cloth, and the shutter of the dark-slide carefully drawn out to its full extent. The plate will then be ready for exposure.