The Optical Magic Lantern Journal (March 1893)

48 The Optical Magic Lantern J ournal and Photographic Enlarger. produced ; on development it will, however, be found quite equally exposed. If the light was not kept moving this irregularity would probably cause trouble-—The magnesium being burnt in a room isolated from the operating chamber, no disagreeable effects are produced on the operator or the air of the room, a matter of some consequence if exposures rapidly succeed one another. The easel consists of a frame supported on feet, between the uprights of which a black board of sufficient size can be raised and lowered and kept in position by a clamping screw. The Fig.2. AA, framework to support the board B, which runs in grooves F; ©, ledge to support plates; D, slotted lath to keep plate in position; E, clamping — > screw to keep board Bin place. board is provided with a ledge along the bottom to act as a support for glass plates, and at the top is attached a slotted lath with a bevelled end tightened with a binding screw to press against the upper edge of the plate and keep it in position. With paper a few drawing pins are all that is necessary. When all is in readiness a small piece of the same kind of paper or plate to be used for the enlargement is placed on the easel where the most important part of the image falls and when there is most variety of contrast—a definite quantity of magnesium is burnt, and the small test paper carefully developed, it can then be seen if the exposure is right or what modifications are required. The enlargement proper can now be done with a correct exposure, and with that same negative or transparency, and the same amount of magnesium, the same results may be ensured with the greatest uniformity, If a lantern is used the centreing of the light must be carefully done, so that the dise of light on the paper is perfectly even and free from those dark patches observed when the light is in the wrong position with regard to the condenser. This applies to any illuminant that may be used. The conditions with regard to the position of the sensitive surface to the lens and its distance from it is the same in all enlarging processes, to describe one is to describe all. With the lantern the principal difficulty is the managenent of the light. Daylight enlargements are to be preferred in good weather when dense negatives are dealt with. The requisites are a clear sky-space a small window outside of and below which a reflector is placed at an angle of about 45: degrees made of some white material or an ordinary mirror made waterproof as regards. its back; a sheet of any white material, but. most things save glass or porcelain are easily damaged by exposure to the outside air. There is no condenser required in this case, the camera being fitted to the window with exactly the same: precautions as there were taken when fitting itto the condenser. On a fine day the exposure is much more rapid than with the best artificial light, and it is always advisable to make test exposures. Owing to the varying quality of daylight cousiderable judgment is required for every exposure, no definite number of seconds for, five minutes together, can be relied on toproduce the same result, unless it is an except tionally fine day with a steady light. _ VIGNETTING. A good vignette is a picture shaded off by imperceptible degrees into the margin, or the background is broken up in an artistic manner, so that its lights and shades shall enhance the value of the picture —a print showing a marginal disc of any definite shape is a bad vignette. Unfortunately we see a good many of them. about. As a rule an abrupt edge to the shading of any picture has a disagreeable effect if intended to represent a vignette—to produce a vignetted enlargement a large card with a suitable irregular shaped opening in the centre is moved gently about between the lens and the sensitive surface during exposure, the: effect of the movement can be watched on the paper or plate, and a few attempt will so: show how to manipulate it, the portion protected from the light by the interposition of the card will of course remain of a whiteness proportionate. to the amount of light allowed to fall on it, and the shape of the gradation will be according to: the judgment exercised on its movements. Some operators prefer a mask hung to the. ceiling by a cord, that when at rest will leave the aperture exactly central for the enlargement. This is kept gently moving during the exposure. Better effects are, in my opinion, produced by a moving screen than by a rigid one fixed near the negative that is to be enlarged, a plan sometimes adopted, but whatever the method, the idea is to gradually soften off the edges of the picture into the plain margin. A thoroughly goo vignette either of portrait of landscape will always afford pleasure. One of the effects of vignetting is to increase the apparent size of the picture; a small picture well vignetted will appear larger than another printed solid and mounted on a similar mount, and have more interest by reason of the suggestiveness an indefinite outline is sure to induce. (To be continued.)