vbl. sb. [f. as prec. + -ING1.]
1. The action of the vb. FOCUS (gerundially).
1851. Ruskin, Mod. Paint., II. III. i. v. § 18. On the right gradation or focusing of light and colour depends, in great measure, the value of both.
1881. Mivart, Cat, 295. Such movement is the focussing of rays coming from points varying in remoteness.
1883. A. Barratt, Phys. Metempiric, 217. The objective universe is the product of the thinking monad, yet apart from phenomena which constitute that universe there can be no thought, no thinking monad, and the thinking monad is made of that which it makes into the universe; the universe is phenomena focussed by a thinking monad, thought is the focussing of phenomena into a universe.
2. attrib. and Comb., chiefly in names of appliances used by photographers, as focusing screen, tube; focusing cloth (see quot. 1890); focusing-glass (see quot. 1858).
1853. Jrnl. Photogr. Soc., I. No. 3. 39/2. The hood is made of india-rubber cloth, and also answers the purpose of a *focusing-cloth, without the necessity of removing it during the day.
1890. Woodbury, Encycl. Photogr., Focusing Cloth. A black cloth used for covering over the head and back portion of the camera to exclude all extraneous light, and to allow of the examination of the image thrown by the lens upon the focusing screen.
1853. Jrnl. Photogr. Soc., I. No. 3. 39/2. The *focusing-glass is arranged so that it will work into the camera.
1858. T. Sutton, Dict. Photogr., Focussing Glass. This is a magnifier used for the purpose of magnifying the image on the ground glass, and enabling the operator to get it into better focus. Ibid. Camera Obsucra.… A dark box, in which the real image formed by a convex lens is received on a *focussing screen.
