Cloud negatives may be purchased. They are generally on paper rendered transparent with wax, or on films of transparent gelatine. They have the immense advantage that they can be printed from with either side towards the albumenised paper, so that each negative presents two lightings.
We think it is a poor thing for the amateur when he becomes an experienced photographer to depend for his skies on negatives taken by others, but the beginner can do nothing better than purchase a few such nega tives as we have described. He will find them easier to work than negatives on glass, and they will serve to give him a good idea of what he is to aim at when he commences to take sky negatives himself.
Before describing the method of printing from sky negatives we will tell how a simple graduated or shaded sky is produced. This sky has an excellent effect in the case of certain subjects. The effect pro duced is generally that of a low sky, or one such as is seen in early morning or shortly before the sun sets. It is therefore suitable for subjects taken at these times or in winter, the shadows being long. It is also suitable for subjects with comparatively straight horizons.
First as to the landscape negative. Before a sky of any kind is printed in, it is necessary that the place which it is to occupy should be white in the print. If the sky of the negative be so dense as to print quite white, well and good ; if not, it is necessary to block the sky out. This is done in the following manner : Some ordinary water - colour vermilion is mixed, gum-water being used instead of pure water, so that it will take readily on the varnished film, and is used with a fine camel's-hair or sable brush. The out line of the horizon is now very carefully painted along on the varnish. A line of vermilion, about a quarter of an inch wide, is thus put on. On the back of the negative we now block out the whole sky, making our blocking overlap that which has been done with great care on the film side. We may use on the back of the plate either Indian ink mixed with gum-water or Bates' black varnish. Either is applied with a some what large brush.
If, before blocking out, the sky printed just a very light tint it is sufficient to block out on the back of negative only, keeping the colour about a sixteenth of an inch away from the horizon line. In this case the narrow fringe of very light tint will not be notice able.
Having got our print with a white sky we proceed as follows : We take a piece of cardboard, tin, or zinc, somewhat larger than the print, and bend it to the shape shown in the sketch,—that is to say, we simply bend up an inch or two of one of the edges. We
now lay the print on a piece of wood or other convenient rest, the landscape portion being covered with the shade from A to B, the sky portions being under the bent-up portion of the shade. The print is taken into the light, when, as will be understood, the top portion of the sky will rapidly begin to change colour, whilst that under the shade does so more slowly, a gradation being produced. The shade is kept moving slowly backwards and forwards over the print till the desired effect is produced. The very same result can be brought about by the exercise of a little skill, the focussing cloth alone being used. In this latter case there is more necessity to keep the shade (the cloth) in constant motion than in the other, or lines be produced.
Now we come to the use of sky negatives. In the first place a suitable negative is to be selected. When one is got we place the print with white sky in contact with it and look through both, the negative being next to us. We shift the position of the one With regard to the other till it appears to us that we have got the clouds in that position which will produce the best sky. We now lay the negative with the print over it on to a printing frame with plate-glass front, the frame being considerablylarger than the negative, so as to allow for the probable fact that, when the best relative position of the print and negative is obtained, the print will extend far below the negative. The former must not be folded back or the albumen will be cracked. According to the nature of the negative the next proceeding varies. If the negative has a tolerably straight horizon line we may use the same shade as we did for the graduated sky. In this connection we must explain that if there be only dark objects, such as trees, etc., against the sky these may be disregarded and the sky may be printed right across them, as it will not be visible. In the ease which we have imagined the shade is used precisely as in the case before. Even if the horizon be not straight, but if the line of it be not very crooked, it is possible to use the focussing or other cloth ; a little skill and constant attention to the print is all that is necessary.