Boys who have cameras, and who have made good collections of views, portraits, and other interesting pictures, may find a great deal of pleasure in entertaining friends with stereopticon exhibitions of their work. The necessary plates and materials may be purchased at any camera or photographic supply store, and with a little patient practice excellent lantern slides may be made. A good magic lantern or stereopticon is a luxury, but for the ambitious boy there is a way to make one at home with but little outlay of money beyond the cost of the lenses and lamp.
A Home-made Magic Lantern
A box, some thin boards, an ordinary central-draught or duplex-burner lamp, a reflector, some nails and screws, a pair of condensing-lenses, and a projector are the materials necessary.
Make a box of half-inch wood, twelve inches long, eleven inches high, and seven inches wide, outside measure. Cut a round hole four and three-fourths inches in diameter at the front of the box, the middle of the hole being eight inches above the inside bottom. Make a door at the back of the box, and fasten a reflector just opposite this hole.
Cut a hole in the top of the box for a lamp-chimney to come through. Nail a piece of half-inch wood eight inches long to the front of the box three inches from the bottom (see Fig. 1). We will call this the deck. Fasten a piece of wood fourteen inches long and four inches wide on either side of the box and deck-piece (see Fig. 2). Perforate the bottom of the box with holes half an inch in diameter, to afford the necessary draught to the lamp. Elevate the box on two cross-sticks an inch wide (see Fig. 2 B B).
Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7.
From an optician or camera supply house obtain a pair of four-inch condensers mounted in a brass barrel, and a quarter-size projector with a rack and pinion. Mount the condensers in the hole in front of the box, supported by means of a block (Fig. 3), fastened on the inside front of the box (see Fig. 4).
In order to adapt the focus of the lenses according to the distance the lantern is from the screen, a sliding front is necessary (see Fig. 5). Cut a base-block scant seven inches wide and six inches long, fastening to it, three and one-half inches from the front, an upright piece of wood high enough to be even with the top of the lantern-box. When the base is resting on the deck in front of the box two small angle-brackets will steady the upright and make it rigid (see Fig. 5). Cut a hole in this upright board so that the centre of the projector mounted in it lines exactly with the centre of the condensing-lenses. This is an important point; if the lenses are not carefully mounted opposite one another the picture will not be clear. Now fit a piece of wood one-fourth of an inch in front of the main box, fastening it at the top with a strip of tin. There must be a hole three inches square cut in this board, the middle of which must line with the centre of condensing-lens. In the opening between this board and the box slip a thin piece of board for the slides to rest on. Set a double-wick lamp or central-draught burner within the box at the proper height, so that the brightest part of the flame will be in direct line with the centre of the reflector and the condensing-lenses.
The principle of the magic lantern is the reflection of the light through the condensing-lenses, which pick up all the light possible and throw it through the slide, which is located directly in front of it. The light is then taken up by the projector, and the pencils of light are thrown onto the screen, at the same time magnifying the picture. This principle is shown by the dotted lines in Fig. 6, which show also the relative position of the lamp, lenses, and reflector.
To keep in the light that would escape through the top opening in the box, put a piece of common stove-pipe (small) over the lamp-chimney. Cut a cap from a piece of tin (Fig. 7 A), the ears extending down inside the chimney to hold the cap in place, when the cap-piece is bent in a half circle as shown at Fig. 7 B.
To cover the space between the lantern-top and the moving front board a piece of black cloth can be used. Or if you have an old camera-bellows it may be made fast to the back of the projector-lens board and to the front of the slide-board located close to the box. It is not necessary to have an absolutely light-tight bellows; indeed, a very good one can be made from some wire hoops with black cloth sewed to them.
In Fig. 8 the wire hoops are shown, and in Fig. 9 the finished bellows, with the cloth stitched in place, is ready to be attached to the boards with small tacks or staples.
When all the parts are assembled, and the lantern is complete (except the bellows, which has been omitted so that the working parts may be more clearly shown), the lantern will appear as in Fig. 10.
A Stereopticon
The cost of a good stereopticon will range from twenty-five to seventy-five dollars, and that sum places it beyond reach of the average boy. The following instructions and illustrations will enable any smart boy, who is handy with tools and light materials, to make a high-grade stereopticon with lamp and mechanism that is capable of doing really good work.
Fig. 8. Fig. 9. Fig. 10.
The materials needed for its construction will be some sheet Russia iron, thin mahogany or cherry boards three-eighths of an inch in thickness and six inches wide, some round-headed brass screws, small hinges, a camera-bellows, and the necessary lenses and lamp. The tools include a light pair of metal shears, a fine-tooth saw and a compass-saw, a small hammer, plane, and screw-driver, and a light cold-chisel.
To begin with, obtain a board twenty inches long, six inches wide, and three-eighths of an inch in thickness to serve as the base-board. Treat this board to several successive thin coats of shellac, and rub down the last coat with fine sand-paper to give it a smooth surface. Cut another piece six inches wide, eight and one-eighth inches long, and in it make a round hole about four and a half inches in diameter, through which the case that contains the condenser-lenses may pass and fit snugly. This board is to be placed nine inches from one end of the base-board, and fastened to it in a standing position with long, slim screws driven into the lower end through the underside of the base-board. Fig. 11 shows the arrangement of these boards, also the runners and sheet-iron hood.
From a sheet of Russia iron cut a piece nine and a half inches wide and twenty-three inches long, and have a tinsmith roll one edge over a piece of wire so as to stiffen it. With a rule and piece of chalk divide and mark off the sheet into three divisions, the end ones measuring eight and a half by nine inches and the middle one six by nine inches.
CONSTRUCTION OF THE STEREOPTICON
Fig. 11. Fig. 12. Fig. 13. Fig. 14 A. Fig. 14 B.
Lay the sheet on a board at the edge of a table so that a chalked line is directly over the sharp edge, and, holding it down firmly with one hand, bend the iron down with the other, forming a right angle. Bend the iron on the remaining line in a similar manner, and the hood is formed.
In the top of this hood, at the middle, mark off an oblong two inches wide and six inches long; then cut out the piece of iron with a cold-chisel and a hammer, laying the sheet-iron on the upturned surface of an old flat-iron. File or emery-paper the edges of the opening to render them smooth, then cut an opening in one side, three and a half inches high by four inches long, for a door.
Through the top hole a lamp-chimney may project that the surplus heat may be carried upward. For the side opening a sheet-iron door should be made and hung in place with small brass hinges, and a brass lever catch to keep it closed.
This catch is a simple little affair, and consists of a thin piece of spring brass, in one end of which a hole has been made, while at the other a little knob handle is riveted. One end is attached to the door, and to the hood beside the door a catch of thin brass is riveted fast, into which the lever catch can drop.
To stiffen the door, the edges should be bound with narrow brass strips, securely fastened with small rivets, or escutcheon pins, that can be adapted as rivets by cutting them to the required length.
Two runners half an inch wide and three-eighths of an inch in thickness are to be screwed fast to the uncovered top of the base-board, four and a half inches apart, as shown in Fig. 11. From sheet-iron cut two strips half an inch in width and ten inches long, and fasten a piece to the top of each runner, using the same screens to hold them in place that secure the runners to the base-board. One-eighth of an inch of each strip will project over the inner edges of the runners, as shown in Fig. 12, and this edge will serve to hold the wooden slide-holder and objective-lens board in the proper position on the base-board.
Make a sheet-iron door six inches wide and seven inches high, with the edges rolled over a wire to stiffen them, and in the bottom of the door, at the centre, cut an opening half an inch wide and two inches high. This will allow the door to be closed over a gas-pipe that may project for a short distance from the rear of the enclosure. Attach this door to the back of the hood with two small hinges riveted at the top, as shown in Fig. 13, and across the under side of the base-board, and two inches from either end, screw battens of wood in which pins have been set. These battens will raise the lantern up from a table or box on which it may rest, and allow a draught to pass up through holes made in the base-board inside the enclosure formed by the iron hood. These draught-holes will be necessary for either oil or gas light, and they can be bored about as shown in Fig. 13.
Two small wooden runners must be fastened to the base inside the enclosure, a distance of four and a half inches apart, and between them a lamp or gas-jet tray will slide.
From the thin mahogany cut three pieces four and a half inches wide and seven inches long. In the middle of these, and four inches from one end, make a centre dot, and with a compass-saw cut a hole in one of them three and a half inches in diameter, and in another cut a hole three and a half inches square.
In the third board make a hole the diameter of the objective lens; then with screws and glue fasten the first two boards together, as shown in Fig. 14 A, so that a space of three-quarters of an inch will remain between them. The height of this opening should be four and a quarter inches, and the holes in the middle of the boards should be centred. These two boards and separation blocks are to be fastened in an upright position to a narrow piece of three-eighth-inch board the same length as the width of the upright boards, as shown in Fig. 14 A; and at the outer edges a saw-cut at the joint will allow this frame to slide back and forth between the runners, so that the iron edge may fit in the saw-cut.
To the inside of the front board two springs should be attached with screws at one end of each; these springs may be shaped from corset steels, and they should be bent in a curved position, as shown at the lower end of the opening in Fig. 14 A. Their use is to hold the slide-carrier back against the rear board and firmly in place. Slide-carriers may be purchased at an optical supply house, and they are made in several shapes; the most convenient ones, however, are the sliding wooden holders that accommodate two slides.
The remaining board is to be mounted on a block and held in place by two angle strips, as shown in Fig. 14 B; and to enable it to slide between the runners it should receive saw-cuts also. Procure a camera-bellows four inches square, or in its absence employ a piece of black silk or gossamer cloth, and attach it to the frames, as shown in Fig. 16, with small curtain tacks and glue. Having mounted these boards on the base-board between the runners, the box is then ready to receive the lenses and lamp.
From a manufacturer of optical goods purchase a pair of four-and-a-half-inch diameter condensing-lenses mounted in a tube, and a quarter-size four-inch back-focus double-objective lens mounted in a tube with rack and pinion adjustment.
Fig. 15. Fig. 16.
The condenser-lenses should occupy the hole in the front of the box, where the tube can be firmly held in place by the inside edge of the hole. The objective lenses are to be attached to the face of the front board in the position shown in Fig. 16; and by means of the sliding-board and bellows the lenses can be adjusted to meet any short-focus range—that is, a distance of fifteen or twenty feet from the sheet on which the picture is thrown.
For use in small rooms a duplex-burner, or central-draught lamp, can be used, and a plan showing the position of lamp, reflector, and lenses is shown in Fig. 15.
A represents the reflector placed behind a lamp having duplex wicks. The centre of the reflector should be directly in line with the centre of the lenses, and the lamp must be placed so that a portion of the flame, three-quarters of an inch above the top of the wicks, will line with centre of reflector and lenses. The light is brightest in oil-lamps, from three-quarters to an inch above the wicks, and, as only a small portion of the light is of use, the most brilliant part of the flame should be employed for projection through the slide and lenses.
B B are the wicks of the lamp, and the fount should be placed so that an imaginary line drawn through the centre of reflector and lenses would pass through the forward edge of one wick and the rear edge of the other. By arranging the wicks at the angle shown on the plan, the greatest advantage can be had from the light.
The positions of the condensing-lenses are shown at C C, and D represents a slide in position at the front of them. E E gives the position of the objective lenses, and the dotted lines F, G, and H, drawn from the reflector edges crossing at the light, passing through the condensers and slides, and out through the objective lenses, show the manner in which the rays of light are collected and thrown through the transparent picture and lenses, and so on through space, until it rests against the large sheet.
To complete the stereopticon an oval chimney is to be made, and fitted with a flange so that it may be held to the top of the iron hood with four little iron buttons or lap-hooks riveted to the top of the hood. This chimney should be four inches long by two inches wide at the bottom, and one and a half inches square at the top, and eight or ten inches high. At the top arrange a light-cap about as shown in Fig. 16, so that the light from the lamp or gas-jet will not throw rays up against the wall and weaken the picture on the sheet.
Precaution must be taken to stop out all surplus light other than that projected through the lenses, since the useless rays tend to weaken the round disk of light on the screen, and render the picture weak and neutral in tone, instead of sharp and vigorous. The wood-work should be given two or three coats of shellac, and the iron parts should be blackened.
Dissolving views cannot be shown in a single lantern, but if two lanterns are fitted with the same kind of lenses, and placed side by side, so that the disks on the sheet are uniform in diameter, it will then be possible to obtain some very beautiful dissolving effects.
Lantern Slides by Contact-printing
Many amateurs have an idea that it requires a great deal of skill to make lantern slides, but any one who can produce a good negative can soon learn how to make a good lantern slide. The simplest way is by contact-printing.
Select a negative free from spots, scratches, or pinholes. It must have fine detail in the shadows, and no harsh contrasts of light and shade. The regulation size of a lantern slide is 3¼ × 4 inches, so choose a negative which will still make a good picture if all but the portion included in these dimensions is blocked out. Cover the part of the negative which is to be blocked out with black needle-paper, or paint it with non-actinic paint, applying it to the glass side of the negative. The negative is placed in a printing-frame, and then by means of a red light the slide-plate is placed over the part to be printed from, the film side towards the negative.
If one has a lantern, the light of which is suitable for printing slides, cover the negative, open the door of the lantern, and then, holding the printing-frame about fifteen inches from the light, expose from five to twenty seconds, according to the density of the plate. A plate that prints quickly will need but five or eight seconds, but a denser plate will require a much longer exposure, often as long as thirty seconds. Cover the plate as soon as it is printed, close the lantern, remove the slide from the frame, and place it face up in the developing-tray. Turn the developer over it quickly, taking care that the whole surface of the plate is covered immediately. Any developer that makes good negatives will make good lantern slides. A weak developer is to be preferred to one which brings out the image quickly. Develop till the detail is well out; wash and fix same as a negative.
As every imperfection in a plate is magnified many times when thrown upon the screen, great care must be taken in the developing, fixing, washing, and drying. When the slides are washed, take a piece of clean surgeon’s cotton and wipe the film very gently, then place to dry where no dust will settle on the surface.
If there are any spots on the plate after washing and before drying, they may be removed with ferricyanide of potassium in solution. Tie a small piece of surgeon’s cotton to the end of a glass rod, dip it into the solution, and touch the spot very lightly. Rinse the plate at once, and if the spot has not entirely disappeared repeat the operation. The ferricyanide works very quickly, and must be rinsed off as soon as applied.
Lantern Slides by Reduction
If your negatives are larger than 3½ × 3½, and it is desired to get the entire picture on the slide, then the reduction process will have to be resorted to. For this work you can use your camera if it has a long bellows, and the work should be done in a room where a window is towards the north.
Obtain a piece of board five feet long and ten or twelve inches wide, and at one end of it erect the negative-board, as shown at Fig. 17. The negative-board or holder should be twelve or fifteen inches square, with an 8 × 10 rabbeted hole at the middle of it, and supported with two brackets, as shown at Fig. 17 B. Kits can be made or purchased to fit in the opening reducing to 6½ × 8½, 5 × 8, 5 × 7, 4¼ × 6½, 4 × 5, and 3¼ × 4¼. With this range of sizes any negative from 3¼ × 4¼ to 8 × 10 can be held in the board. Now arrange two strips of wood at each edge of the long base-board, so that the camera can slide forward and backward on a platform built to support it, as shown at Fig. 17 D.
The camera should be made fast to this moving platform with wood cleats and screws, and it should be mounted high enough so that the centre of the lens will be exactly on a line with the centre of the opening in the upright board, as shown by the dotted line in Fig. 17. At the upper corners of the plate-board arrange slim, steel-wire nails with the heads cut off, and bore holes near the ends of sticks three-quarters of an inch square so that they will fit down over the nails, as shown at Fig. 17 E. The other ends of the sticks should rest on the top of the camera. Over these sticks a dark cloth should be thrown when making photographs of negatives, to keep out light and prevent the high light from the window affecting the action of the lens.
To make a reduction of a large negative, fill the plate-holders with 3¼ × 4 lantern-slide plates, having obtained kits to fit your holders; then clamp a negative upside down on the board, as shown at A. Mark the lantern-slide size with a lead-pencil on the ground glass of your camera, taking care to centre it; then move your camera forward or backward and operate the bellows until the correct size has been obtained. Focus as sharp as you can; then stop down your lens with the smallest diaphragm. Experience will dictate the proper length of time for exposures. No definite rule can be laid down, for the varying conditions of light, rapidity of plate, and state of the weather—all will have to be taken into consideration.
Fig. 17. Fig. 18. Fig. 19. Fig. 20. Fig. 21. Fig. 22. Fig. 23.
Lantern slides made by reduction are always sharper and better than contact slides, and whenever possible they should be made after this fashion, even from films which may be held flat between two plates of clear glass. A piece of white tissue-paper should be pinned against the window towards which the camera points, so that a blank white light will be beyond the negative, thereby avoiding the possibility of picking up any false lights or shadows.
Lantern slides should always be masked, so that the actual sight-opening through which the lantern-light is projected will be two and three-quarters inches wide and two and a half inches high. A mask form can be purchased or made from sheet-brass. The opening and the other dimensions should be of the same size as the lantern-slide plate, or 3¼ × 4 inches. The masks should be cut from black needle-paper with a rotary cutter, having first prepared a number of the blanks of the proper size; then the openings can be cut as shown in Fig. 18. A smaller mask for the central part of slides can be made two inches wide and two and a half inches high, as shown in Fig. 19, and for portraits an oval mask is the best (see Fig. 20). Covering-glasses or crystals are necessary in making slides. Old lantern slides can be cleaned and used for this purpose, or some very thin, white glass may be cut into 3¼ × 4-inch plates.
To mount slides lay a mask against the film-side of the plate, or positive, and over this place a clean, clear covering-glass, as shown at Fig. 21. With binding-tape (which comes in white and black) first bind one edge, as shown at Fig. 22, arranging the paper tape so that an equal margin will be visible on both sides. Bind the opposite edge, and then cut away the projecting ends of the binding. Proceed to close the short ends in a similar manner, and as a result you will have a finished slide, as shown in Fig. 23. Some slide-makers begin at one corner and run a strip of binding all around the edge without cutting it. This is a little difficult to do at first, but if you have a clamp that has a compression-screw and will turn on its axle, it simplifies matters greatly. Some amateurs prefer black binding-tape, others white. The white tape with black masks makes a neat-looking slide, and if the margin is wide enough the title of the picture may be written on it.