Photographic optics and colour photography [electronic resource] : including the camera, kinematograph, optical lantern, and the theory and practice of image formation (1909)
Johnson, G. Lindsay (George Lindsay), 1853-, Parsons, John Herbert, Sir, 1868-1957, donor, University College, London. Library Services · London : Ward & Co. · leaf 189
1 65 object be brought still nearer the lens the image recedes and becomes larger than the object until the object arrives at F, when the image vanishes, being at infinity. Taking our standard formula F = xy .... [70] F2 _ FJ [71] We find x = — and // = - y J x Example. — The lens is 10 in. in… … Fig. 125. — Graphic demonstration of the formula xy — F3. 5F + F = 6 times F, or 60 in. from the lens ; but O, on the contrary, must be at a distance equal to the reciprocal of 5 or 1/5F from F, or F/5 + F = 2 + 10 in. or 12 in. from the lens. Or the problem may be worked from the above formula…
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