Enlarging can also be carried out without condensers by col lecting the rays of an illuminant in a reflector of ellipsoid form from which a parallel beam of sufficient size is passed through the negative. The latter may be held in the dark slide of an ordinary camera which, with its lens, is thus made to take the place of the front portion of an ordinary enlarging lantern.
The Photostat, an American invention introduced about 1907 and since greatly developed, is a combined camera and stand with fully automatic mechanism for the reproduction of various kinds of official and commercial documents by unskilled operators in any ordinary well-lighted office. Any scale of enlargement or reduction can be adopted, and copies developed and fixed in not many seconds. A very rapid colour-sensitive paper is used, render ing the system valuable for copying engineers' and architects' plans, etc. See B..1 .A. for 1928, p. 180. (See LITHOGRAPHY.) Stands.—For studio cameras (q.v.) as previously noted, stands of substantial "pillar" construction are usually provided. With copying and other large cameras the stand is more often in the form of a table, but also provided with raising, lowering and tilting movements. For enlarging purposes the stand and easel are
sometimes combined, runners enabling the conjugate distances to be readily varied. But for all general photographic purposes the tripod form of stand is the most practical, and almost innu merable patterns in wood and metal have been evolved. For very small cameras tripods with telescoping legs of an aluminium alloy and a top of harder metal meet the demand for extreme port ability, but for serious work a substantial wooden pattern is greatly to be preferred. The legs should telescope to make them not only more portable but also adjustable to uneven ground. For special work a revolving or tilting head may be desirable, and in some patterns provision is made for increasing the height of the camera from the ground by means of a second raised head. An important new device is a tripod with a universal ball and socket which compensates for weight and tilt of camera.
For the incidental snapshot work to supplement the ordi nary tripod, a "unipod" is employed as a support for a tele photo or other heavy lens affixed to a camera which is of frail construction.