In times past, some fault has been found with flash-light pictures on account of the so lions expression of the subject, caused by the expected explosion of the powder, or the closed eyes, which are characteristic of pictures secured by flash lights that are not practically instantaneous.
It follows that a flash light must do its work "quicker than a wink," and that it must be ignited by some device other than a fuse or atrip of paper, either of which gives warning, and thus puts the subject on guard. Flash-light lamps are undoubtedly good, but they are all limited in certain ways. In the first place, it is necessary to compress a bulb to force air through a greater or less length of tube. This requires some effort on the part of the operator, and practically prohibits him from including himself among his subjects. If he does attempt to do this, the rubber tube leading from the bulb to the lamp must necessarily form an unsightly addition to the picture; and, furthermore, the tube is limited as to its length, on account of the air friction, which so reduces the blast in a tube of considerable length as to entirely defeat the operation of the light.
After enumerating these objections to the ordinary flash-light lamp, it is perhaps unnecessary to allude to the matter of expense.
In Figs. 72 and 73, is shown flash light apparatus, the cost of which is practically nothing, as the needed materials may be purchased for a few pence, and the labour involved is a matter of only a few minutes. A description is hardly necessary, the engravings tell the whole story.
Two loops soldered to the bottom of a small tin pan receive a wire, which is bent at one end, forming a spiral, into which is inserted a little roll of asbestos. A fish-line sinker is placed on the wire previous to bending, and near the pan the wire is bent to form a shoulder, which holds the wire in a stable position when raised, as shown in Fig. 72. The other extremity of the wire is bent at nearly a right angle and formed into a loop, then returned to form a practically T shaped arm with an open eye at its extremity. A stout black thread of sufficient length to reach as far as may be required is tied in the loop.
At the point in the surface of the pan where the asbestos strikes when pulled over, a shallow cavity is formed by burnishing the tin with a rounded instrument like a tool handle, the tin being placed over a cup, a box cover, or something of that kind, which will support the metal around the cavity during the operation of burnishing.
The pan is secured to a heavy wooden block, or to any fixed support, by means of two or three tacks driven through its rim. One or two boxes of Blitzpulver should be placed in the cavity in the tin; a few drops of alcohol are poured on the asbestos; the apparatus is placed on a step-ladder or other high support, which is located at the side of the camera in such a position as to prevent the light of the flash from entering the camera tube. A large piece of white paper is suspended at the back of the apparatus, and 18-24 in. distant. If the operator is not included among the subjects, the black thread is simply connected with the lower loop, so that a rearward pull of the thread will tilt the wire arm forward. If the operator desires to include himself in the picture, the thread is slipped into the eye at the end of the wire, so that pulling the thread from the front will tilt the wire arm forward. Now, everything being ready, the alcohol is lit, the operator takes his position, pulls the thread, and the thing is done.
When the subjects are so posed with reference to the source of light as to produce undesirable dark shadows, this trouble may be avoided by arranging newspapers so as to reflect more or less light on the shaded side.
To secure good flash-light pictures, two things in addition to a good instrument are required: one is an instantaneous light of sufficient intensity, the other is an instantaneous plate of the kind known as isochroroatic or orthochromatic.