In the center of the material cut a hole, the full aperture of the lens, for exposures. ‘Whilst setting this shutter by so winding it, the hole in the front lid of the camera is, of course, closed with its slide. When an exposure is made, this slide is with-drawn, and the pall released by a trigger. This can be effected with a string attached to the pall, passing through a small hole in the bottom of the camera, or by a spring trigger. A shutter that may be preferred is the revolving shutter, used in all the cameras by Lancaster and Son, of Birmingham. It has the advantage of being get-at-able, as it would be attached to the hood of the lens, the firm would supply one to any measurement and its speed can be adjusted at will. Its trigger can be easily released by passing a wooden peg through a hole in the top of the camera, letting it simply rest on the trigger, which can then be depressed by pushing down the peg with the finger.
The peg would only just protrude sufficiently. Even the common drop-shutter could be adapted by allowing the drop to pass through slits in the top and bottom of the camera, immediately in front of the lens. These slits need not be light-tight. The finder, which is absolutely necessary, consists of a diminutive camera obscure attached to the hand-camera, by looking down into which the objects can be seen that are directly in front of the lens, and will appear on the negative. Briefly it is made by reflecting upon a piece of mirror, placed exactly at an angle of 45 degrees, the picture through any very short focused single lens, a common No. 10 sight spectacle lens will do fixed vertically, and directly towards the center of the mirror. The picture being thus reflected upwards, vertically, the finder must have a piece of finely-ground glass fixed horizontally, and by looking upon this the proper moment for making an exposure is ascertained. The finder is attached inside the front of the camera in one corner. A finder such as described can be purchased for two or three shillings. The first and only adjustment of the finder consists of fixing upon an object which is in focus in the camera, as already described for the adjustment of the camera-lens, care being taken that the object is exactly in the center of the ground-glass. Then, without moving the camera, the finder must be adjusted and affixed so that the object on the ground-glass is exactly in the center of the ground-glass of the finder.
Make a piece of small rubber maid tubing which can be obtained from a chemist about tie one end of it firmly with a piece of fine string about fin. from the end, so that no air can escape at that end. Procure from the chemist a small india rubber ball, fitted with a nozzle, and push the other end of the tube over the nozzle to form an air tight joint. If the joint is not air-tight it can be made so with which is melted over it by heating the glue in the flame of a candle or spirit-lamp, just as sealing-wax is melted. When cold it will be firmly glued to the nozzle. This forms the Pneumatic Release, and has to be fitted to the shutter.