From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Guide to the external supply adaptor lamp, illuminator lamp, mounting, and calibration for a photometer.
| Identifier | ExFiles\Box 168a\3\ img518 | |
| Date | 1st May 1950 | |
| LAMP FOR THE EXTERNAL SUPPLY ADAPTOR (Photometer Lamp) The external supply adaptor and lamp (Figs. 8 and 9) take the place of the normal battery container and lamp used for exposure estimation. The adaptor consists of a machined metal barrel, closed at its upper end by a disc fitted with an aperture carrying a diffusing screen. Its lower end is threaded to carry the photometer lamp holder which in turn is mounted in an auxiliary base ring to fit the body of the photometer itself. This auxiliary base ring screws into the position on the photometer body normally taken by the 'operating ring' when the photometer is used for exposure estimation, and indeed the operating ring, with its push button switch screws into an outer cavity of the auxiliary base ring in which are situated the insulated contact and other terminal for the lamp circuit. The leads to the lamp are brought in from two plugs through a hole in the auxiliary base ring, the lamp being operated by the push-button switch in the normal way. The plugs for the photometer lamp circuit are used to connect the lamp and button switch with a two socket connector on the top of the transformer box. The sockets are themselves connected inside the transformer with the 6-volt output terminals of the transformer. THE ILLUMINATOR LAMP AND ITS MOUNTING The illuminator lamp is carried on a swivelling arm inside the illuminator. Its purpose is to illuminate the opal window in the top of the illuminator which is used as the platform of the densitometer. A lead screw terminating in a knob on the upper side of the transformer box, enables the distance of the densitometer lamp from the opal window to be adjusted so that the brightness of the opal window can be fixed at a convenient level and so that the zero of the relative density scale can be made to correspond with absolute zero density. The illuminator lamp is connected in parallel with the external supply adaptor (photometer) lamp. A switch on the top of the illuminator enables this lamp to be switched off. The lamps employed are 6-volt, 6-watt, two-pole motor car side lamp bulbs with small bayonet cap fittings, Osram Reference No. 80. Calibration The S.E.I. exposure photometer is sufficiently accurate for most ordinary densitometry. If, however, density values are required to be compared with those obtained on different instruments to an accuracy of better than ±0.04, the instrument should be calibrated against densities of known values. Strips of film carrying about 15 measured densities between 0 and 4 may be purchased from Ilford Limited. ILFORD LIMITED ・ ILFORD ・ LONDON SE/A/L.50/5 10 Printed in England | ||