International photographer (Jan-Dec 1941)

EXPOSURE METER (Continued from page 19) The coil is held in place by an armature shaft of hardened steel tapered at each end to a point much finer than a needle. The shaft is mounted in sapphire jewel bearings vertically, which minimizes friction. Two small torque springs mounted near each end of the shaft oppose the coil as it tends to turn in the magnetic field created by the strong permanent magnet. Thus, the more light falling on the cell the more current, and the higher the quantity indicated by the pointer. The precision and quality is such that the instrument can be calibrated and guaranteed to have a full scale accuracy of within 2%. The cell and the instrument are mounted in a special case, designed to absorb shocks and sealed against moisture. The scale plate is calibrated in foot-candles, the standard light measuring unit in the United States. This makes it a simple matter to check the accuracy of the instrument with any standard light power. One camera user went so far as to mount five ordinary candles one foot away from his General Electric exposure meter and observe that it indicated five foot-candles. This is not an accurate checking method because the standard candle has certain specifications: It must be of a certain size with a certain size wick, certain length of wick, and burn a certain amount of wax in a certain specified period. (Concluded in July issue) 4000 4400 4800 5200 S600 6000 6400 6800 WAVE LENGTH OF LIGHT (ANGSTROM UNlTSj Fig. 4 curve classifications 1relative density produced by various wave lengths of light. 2 relative proportions (logarithmic a5 seen by film) of various wave lengths in daylight. 3 " effect " " " " on cell. 4 " " " " OH EYE. FlG. 5 Performance of cells exposed to bright daylight (placed directly below a skylight) not protected by hood or multiplier. IO 12 14 MONTHS EXPOSED Fatigue teats on a dozen cells. The steady output shown assures continuous acouracy of ttie exposure meter as any aging of the eleotrloal element Is negligible. 28 GENERAL ELECTRIC MIDGET PHOTOFLASH LAMP, NO. 6 A new tiny focal plane photoflash lamp — same size as GE's mighty midget No. 5 and the recently introduced speed midget I SM ) — has just been announced by General Electric's lamp department at Nela Park, Cleveland. Full name given to this latest midget flash bulb is G-E Mazda Focal Plane Photoflash Lamp, No. C. It has a list price of 15 cents. Outstanding features and essential tech j nical data of the new "No. SIX" are as follows: A Bll bulk filled with shredded foil; a single contact bayonet base; light output rated at 16,000 to 18.000 lumen seconds; and, 500,000 peak lumens. As in the case of the other two G-E midget photoflash lamps, the new No. 6 permits use of smaller and more efficient reflectors than has been possible with the larger Mazda photoflash lamps. Timelight characteristics of the new lamp's flash are such that it may take the place of the present focal plane flash bulb No. 31 in many cases. The flash of the new lamp has an effective duration of approximately 0.030 second. Accordingly, the lamp may be synchronized with the great majority of focal plane cameras in use up to and including the 2Vi x 3^ size. For best results some small focal plane cameras may require the longer flash duration of Photoflash lamp No. 31. Employed in an efficient, well-designed reflector, (the same as used with No. 5 and Type SM photoflash lamps) the new No. 6 lamp gives an : exposure approaching that obtained with larger focal plane photoflash lamps. Development of the focal plane No. 6 permits photographers to "virtually hold in the palm of one hand" a trio of midget G-E flash bulbs, simplified ammunition designed to satisfy the countless needs of the growing army of flash photographers and the wide assortment of equipment used in shooting pictures. CLASSIFIED ~ LARGE QUANTITY OF PROFESSIONAL CAMERAS AVAILABLE. WRITE FOR BARGAIN BOOKLET. BURKE & JAMES, INC., 223 W. MADISON ST., CHICAGO, ILL. WANTED TO BUY FOR CASH CAMERAS AND ACCESSORIES MITCHELL, B. & H., EYEMO, DEBRIE, AKELEY ALSO LABORATORY AND CUTTING ROOM EQUIPMENT CAMERA EQUIPMENT COMPANY 1600 Broadway New York City Tel. Circle 6-5080— Cable : CINEQUIP BELL & HOWELL, 5-WAY SOUND PRINTER. CAMERA EQUIPMENT COMPANY 1600 Broadway New York City Tel. Circle 6-5080— Cable: CINEQUIP ' MITCHELL NC 112. LIKE NEW. Up to the minute. B. B. RAY, 300 W. Durante Road, Arcadia, Calif. FOR SALE: AKELEY CAMERA, like new, No. i 258, with roller pressure plate, new tripod and legs, all new gyro wears, six magazines, 35 mm. F2:3 matched pan astro lenses, 50 mm. F2:3 matched pan astro lenses, 100 mm. F3:5 matched' Carl Zeiss lenses, 12-inch F 5 :6 Dahl Meyer Telephoto lens. All equipment in cases. 230 and 180 degree interchangeable shutters. Ten metal filter holders in case. Sacrifice $900. MERVYN FREEMAN. 12041 ADDISON ST., NORTH HOLLYWOOD, CALIF.