Owing to the diversity of the types of vertical. enlargers, we advise that their detailed descrip tions be studied in the leaflets and catalogues issued by the makers.
763. Box Enlargers. Box enlargers, often of tapering shape, are, in fact, small triple-body cameras of very simple construction consisting of a rigid box carrying, at positions suitable for a given degree of enlargement, the negative (covered at some distance by a piece of ground glass), the lens (usually of a cheap, simple type, but greatly stopped down), and a paper holder (which may be a removable dark slide or simply an integral part of the box) in which the paper is pressed flat by a plate against a sheet of glass. These instruments, exclusively designed for use in daylight for enlarging the small negatives made by amateurs, have been manufactured in a variety of patterns, of which only the simplest and lightest have survived. Some of them, made almost entirely of mill-board, give quite satis factory results so long as they are not subjected to rough usage.
The introduction of vertical enlargers, capable of being used at any time, has led to the manu facture of the better types of box enlargers being abandoned. This is especially the case as regards
the patterns permitting of several degrees of enlargement, some of which were of extremely ingenious design.
764. Various Enlargers. From time to time there have been made, for amateur use, attach ments interchangeable with the dark slides of a hand camera. These attachments consist of a negative carrier and of a light-box for illumina tion by diffused light, generally in the form of a matt-white reflector, either plane or parabolic. This is illuminated by one or more lamps placed on the sides in recesses which shield the negative from direct rays. These enlargers are used like a projection lantern, the image being projected on an easel fixed to the wall.
There are also available commercially box enlargers fitted with a light-box for diffused light or with a light-box for directed light ad justed once and for all by the maker.
Finally, many of the photographic cameras taking standard size cinematograph film may be fitted to special attachments, so that the whole forms a vertical enlarger.