초록 ▼

This invention relates to large, ie view-cameras and supplants the fixed conventional viewing screen by using instead a focusing frame partly or totally geometrically congruent with the sheetfilm holder for such a camera, said frame being temporarily inserted into this camera for focusing, the conve

This invention relates to large, ie view-cameras and supplants the fixed conventional viewing screen by using instead a focusing frame partly or totally geometrically congruent with the sheetfilm holder for such a camera, said frame being temporarily inserted into this camera for focusing, the conventional sheetfilm-holder partition being replaced in the focusing frame of the invention by a transparent viewing screen of which the focusing surface faces the lens. In this manner the invention achieves coincidence, within a desired and optionally zero tolerance, of film emulsion plane and focusing surface and eliminates the errors related to uncertain positioning of the conventional viewing screen of a large-format camera.

대표청구항 ▼

[ I claim:] [1.] A method for quickly and reliably focusing a lens-equipped large-format camera from which the conventional viewing screen has been eliminated and fitted with a recess for receiving a conventional partition-fitted sheet film holder optionally loaded with sheetfilm(s) evincing an emul

[ I claim:] [1.] A method for quickly and reliably focusing a lens-equipped large-format camera from which the conventional viewing screen has been eliminated and fitted with a recess for receiving a conventional partition-fitted sheet film holder optionally loaded with sheetfilm(s) evincing an emulsion surface, whereby said recess initially receives a focusing frame congruent as a whole or in part with the conventional sheetfilm holder and containing a transparent focusing screen optionally exactly congruent with the conventional sheetfilm holder partition and having a focusing surface facing the lens, and focusing is carried out at said focusing surface to determine and affix a particular plane of focus in the camera, whereupon said focusing frame with its focusing screen is withdrawn from said recess, and said sheetfilm holder, holding at least one sheetfilm with emulsion to be exposed, is inserted into said recess for picture-taking, the location of said focusing frame's focusing screen relative to said sheetfilm holder's partition having been so designed that, within a predetermined tolerance, including zero tolerance, the emulsion surface of the sheetfilm in the inserted sheetfilm holder shall coincide with said determined and affixed plane of focus.