The popularity of lantern slides, and especially of colored ones, as a means of illustrating songs, has caused so large a demand for this class of work that almost any amateur may take up slide making at a good profit. The lantern slide is a glass plate, coated with slow and extremely fine-grained emulsion. The size is 3-1/4 by 4 in. A lantern slide is merely a print on a glass plate instead of on paper. Lantern slides can be made in two different ways. One is by contact, exactly the same as a print is made on paper, and the other by reduction in the camera. In making slides by contact, select the negative and place it in the printing frame and put the lantern plate upon it, film to film. Clamp down the back and expose just as in making a print. A good method of exposing is to hold a lighted match about 3 in. from the frame for three or more seconds according to the density. Development is carried on in the same manner as with a negative. The image should appear in. about a minute, and development should be over in three or four minutes. If the exposure has been correct, the high lights will stay white throughout the development and will come out as clear glass after fixing. It is best to use the developers recommended by the manufacturer of the plates used, the formulas being found in each package of plates. It is best, also, to use a plain fixing bath, which must be fresh and kept as cool as possible in hot weather.
The lantern-slide film that is new on the market can be handled in the same manner as the glass-plate slide, except that the binding is different. The results are the same and the slides are not so bulky to handle. Being unbreakable, they are much used by travelers. The manner of binding for use in a lantern is described on the circular enclosed with the film.
The camera as it is arranged in front of the window for reducing the size of a picture, and the method of binding the slides
When the negative is larger than the lantern-slide plate, and it is desirable to reduce the entire view upon the slide, a little extra work will be necessary. Select a room with one window, if possible, and fit a light-proof frame into it to keep out all light with the exception of a hole in which to place the negative, as shown in Fig. 1. Unless this hole is on a line with the sky it will be necessary to place a sheet of white cardboard at an angle of 45 deg. on the outside of the frame to reflect the light through the negative as shown in Fig. 2. Make or secure an inside kit to place in the plate holder of your camera to hold the lantern slide plate as shown in Fig. 3. Draw lines with a pencil, outlining on the ground glass of the camera the size of the lantern slide plate, and in the place where the plate will be in the plate holder when placed in position in the camera. This will enable you to focus to the proper size. Place the camera in front of the hole in the frame, place the negative in the hole and focus the camera for the lantern slide size. Expose with a medium stop for about 20 seconds and treat the plate the same as with the contact exposure.
When dry the lantern slide plate may be tinted any color by means of liquid colors. These can be purchased from any photo material store. In coloring the slide plate it is only necessary to moisten the gelatine film from time to time with a piece of cloth dampened in water. The colors may then be spread evenly with a soft brush, which should be kept in motion to prevent spots.
The slide is put together by placing a mat made of black paper, as shown in Fig. 4, on the gelatine side of the lantern slide, A, Fig. 5, and then a plain glass, B, over the mat, C, and the three bound together with passepartout tape, D. Contrasty negatives make the best slides, but the lantern slide plate should be made without any attempt to gain density.
A great many persons who have magic lanterns do not use them very much, for after the slides have been shown a few times, they become uninteresting, and buying new ones or even making from photographic negatives is expensive. But by the method described in the following paragraph anyone can make new and interesting slides in a few minutes' time and at a very small cost.
Secure a number of glass plates of the size that will fit your lantern and clean on both sides. Dissolve a piece of white rosin in a half-pint of gasoline and flow it over one side of the plates and allow to dry. Place the dried plate over a picture you wish to reproduce and draw the outline upon the thin film. A lead pencil, pen and ink or colored crayons can be used, as the rosin and gasoline give a surface that can be written upon as easily as upon paper. When the slide becomes uninteresting it can be cleaned with a little clear gasoline and used again to make another slide. A slide can be made in this way in five minutes and an interesting outline picture in even less time than that.
This solution also makes an ideal retouching varnish for negatives. --Contributed by J.E. Noble, Toronto, Canada.
It has long been a puzzle to me why round cornered masks are almost invariably used for lantern slides, when most works of art are included within rectangular spaces, says a correspondent of Photo Era. Certainly the present commercial masks are in very poor taste. The worker who wishes to make the most of every slide will do well to cut his own masks, not only because of the fact just mentioned, but also because he can suit the size of the opening to the requirements of each slide. Slides can be works of art just as much as prints; so that masking a slide becomes just as important as trimming a print, and equally worthy of individual treatment. It is folly to give each slide a mask opening of uniform size and shape.
When many slides are to be masked, it becomes tedious work to treat each one separately, unless some special device is used. The accompanying drawing shows a way to mark masks which is simple, practical and costs nothing. The drawing is exactly lantern slide size.
Lay the slide over such a guide and note the size of the opening best suited to the picture. This will be determined by the intersection of the ruled lines, which are numbered for convenience in working. If the size wanted is No. 4 for width and No. 2 for height, place the guide over a piece of black mask paper and prick through the proper intersections with the point of a pin. This outlines the desired opening, which may then be cut out easily with a knife and straight edge.
The black paper from plate boxes and film rolls is excellent for making masks. It should be cut up in pieces 3-1/4 by 4 in. and kept ready for use at any time.
Form for Marking Out Rectangular Lantern Slide Masks
Purchase some lantern slide plates and fix in hypo without exposing, in the usual manner, same as you would an exposed plate, says the Moving Picture World. This leaves a thin, perfectly transparent emulsion film on the glass, which will readily take color. Mix a rather weak solution of clear aniline dye of the desired color and dip the plate in it, wiping the plate side clean. If not dark enough, dip again and again until desired tint is attained, letting it dry between each dipping. A very light blue tint slide will brighten a yellow film considerably, but the tint must be very light, just a bare tint.