The Optical Magic Lantern Journal (May 1894)

100 The Optical Magic Lantern Journal and Photographic Enlarger. Opening on that side; the next thing is a table, which should be about eight feet in length, and a little wider than the largest picture which may This table should be of such a be required. height that the centre of the negative, when placed in position in the window, and the axis of the lens of the camera on the table, are ina line. The table should have at its end furthest from the window an easel attached, to which is fixed the sensitive paper on which the enlargement is to be made. The table used by me is in two pieces, and the focussing is first performed by sliding in, or pulling out, the front part of the table, and finally by the milled headed screw of the lens. But should the table be in one piece, it should have at its end furthest from the window, and for a |; length of two feet or so, a slot cut in its middle, to enable the easel to traverse backwards or forwards ; to the easel a clamping screw should be attached, so that when the required adjustment has been made, it may be clamped tight and kept in that position; as a further precaution, two strips of wood should be fixed at either side of the table, which will prevent any movement of the easel. The sketch above shows the table both as a sliding one, and, in the event of its being in one piece, the slot and slide pieces as recommended. The focussing should be first done on a sheet of white paper fixed to the easel, a sheet of ‘bromide paper being afterwards substituted for it. As the negative to be evlarged should be well and equally lighted, it is necessary to have for this purpose a reflector on the outside large enough to illuminate the negative thoroughly, and which can be of white cardboard or a mirror glass fixed at an angle of 45°, and controlled from the inside by a string. As no light but that which passes through the negative should enter the dark room, it is necessary to close the whole of the window effectually except a portion ‘which should contain a frame. This frame should have on the outer side a groove for a ground-glass 12in. by 10in. in size, and on the inner side, leaving a space of.four or five inches from the ground-glass, an arrangement for carriers to fit from the largest to the smallest size negative to be used. The negative to be enlarged should be well defined and full of detail, with sharp definition, aod with a slight tendency to thinness; fix this in the carrier in the window with the film side towards the lens and upside down. Then take your camera (I use the one with which the negative: was taken), and taking out the focussing glass, push it up as near as possible to the negative, the lens pointing to the easel, and shut out carefully all light at the junction of the camera back and window; and having decided on the size of the enlargement, tix your lens and easel in position in accordance with the following formule, viz., multiply focus of lens by one more than the number of times of enlargement required. This will give the distance from lens to enlargement ; then divide the product by the number of times the negative is to be enlarged ; this will give the distance from lens to negative. For instance, suppose you are working with a lens of 12in. focus and wish to enlarge your negative four times, then 12 x 50 -: 60, or 60 in. is the distance of lens from enlargement or easel, and 60 + 4-=15, that is, 15 in. is the distance from the lens to negative. Now focus sharply and accurately the imagé thrown first on a sheet of white paper pinned to the easel and see that it is evenly and well illuminated ; then cap your lens, insert the necessary stop, substitute a sheet of bromide paper for the white, uncap and expose. To ascertain the correct exposure, expose and develop a small strip of bromide paper on that part of the picture containing the greatest contrasts ; do this a few times, +ill correct exposure has been attained, and regulate subsequent exposures from that negative by the result. Should it be desired to vignette an enlargement, cut a suitable aperture in cardboard and allow the rays to pass through it, moving the card to and fro between the easel and lens dttring the exposure. Alpha paper may also be used for enlarging, and yields prints of very pleasing tones, either with or without toning, to develop which the instructions sent out with the paper, if followed, will give excellent results. Several developing formule are given at the end of this paper, all of which are well and highly recommended. The paper after exposure and before development should be soaked in water till quite limp ; the water is then thrown off, and the developer poured over it. Should the exposure have been