The Optical Magic Lantern Journal (May 1901)

The Optical Magic Lantern Journal and Photographic Enlarger. 55 solution. Of course, if a cold black tone is desired, then a much shorter exposure is needed, and the plate must not be put into the re-strained developer at all; but a cold black tone is seldom needed, and when it is one must risk the exposure, and if it is not correct try again. a Lantern Slide Hints. es) é & TpXwnrw is no more delightful way of ‘pam making positives from the negatives G \ we have called into existence during (ai } the summer than to prepare lantern C<—— transparencies of them, because a photograph looks its best in lanternslide form (the detail and gradation cannot be reproduced so well in any other way). The work may be done at eveningtime, and the evening’s work finished off in an hour, or in several hours, according to the number of slides we can spare leisure to make. Lastly, the slides may be used to entertain our friends as well as ourselves when projected, and are just as good as prints for exhibition to visitors around one’s table. Indeed, the (to ladies especially) novel idea of a photograph on glass adds interest. ‘I cannot think, you know,” exclaims the fair one who is being entertained, ‘‘ how you do them on glass.” There is nothing particularly difficult about slide-making, and the plate-maker’s instruetions, supplemented by one of the excellent manuals on the subject, ought to make smooth the path of the veriest beginner. I am therefore going to give here only a short series of notes touching points which may arise in the reader’s mind before he purchases his first box of Janternplates or after his first attempts. Should they appear fragmentary, I beg the reader’s indulgence. Without repeating much which can be found in every text-book, I want to anticipate what questions or difficulties may arise. A lantern plate is of so much thinner glass than the negative plate that itis easy to make a mistake and put the glass side next the negative. Here is an infallible test: Breathe on the plate on the side you believe to be the glass. If you are right you will see a dew on the glass; if the film side is uppermost there will be none, the gelatine absorbing the moisture of your breath. Waat Puate To Use.—Begin with a slow plate, such as Thomas’s, Mawson & Swan’s, Cadett’s, Edwards’s Special, or England’s Rapid Chloride. The fineness of grain in a slow plate is generally better, there is greater latitude in exposure, and a brighter and more comfortable yellow light can be used. Indeed, Thomas's plates (and the others too, no doubt) may be developed in the shadow of some screen cast by ordinary gas or lamplight, but direct light fogs them. Fix on one plate and stick to that. RepuctTiox or Contact. Unless your negatives are 3 inches square (or less in area) you will not be able to include the whole on the lantern plate; hence the reduction process, in which the negative is virtually copied in the camera on the lantern plate. Reduction means (1) much more trouble, (2) a rapid lantern plate, and (3) very often a less desirable pictorial result, for many hand camera pictures are all the better for being sliced down liberally ; therefore I advise contact. ; : Waicu Drvevorer.—I prefer pyro-ammonia, which gives better colour and_ greater transparency in the image than other more popular developers. Pyro ae oa .. 2 grains 44 gms. Potass meta-bisulphite 6 grains 14 gms. Ammonium bromide .. 2 grains 43 gms. Water ‘ lounce 1,000 c.c. B. Liquid ammonia (880) 8minims 14 c.c. Water 7 -» lounce 1,000 c.c. Use equal volumes of A and B. This gives a very pleasing warm black to brown tone, according to the plate. Care must be taken not to overwork it, or if stains. It is best not to use it twice, and as it is weak in pyro, it is not expensive to do this. ; Strong black tones are obtained with the following hydroquinone formula :— A. Hydroquinone .. 8 grains 18°5 gms. Soda sulphite . 44 grains 100 gms. Potass bromide .. 2 grains 4:5 gms. Citric acid 3 grains 7-0 gms. Water -. lounce 1,000 c.c. B. Caustic soda 8 grains 185 gms. Water é .. Llounce 1,000 c.c. Use A, 1 volume; B, 1 volume; water, 2 volumes. This solution may be used several times. One ounce will develop four to six plates. The colour is a cold bluish-black. Fixinc.—Use an acid bath. The simplest is made by throwing some meta-bisulphite of potassium into the ordinary fixing bath when hypo is being dissolved; or commercial acid baths (e.g., Griffin’s acid-hypo) are very suitable.