International photographer (Jan-Dec 1934)

April, 1934 The INTERNATIONAL PHOTOGRAPHE \< Twenty three is made, development, etc. There is no uniformity in this matter, each laboratory employing its own method. There is, however, an aid which compensates for all these inaccuracies, and that is the latitude of the emulsion. Every emulsion can stand a definite amount of deviation from the correct exposure, either under, or over, and still produce a correctly exposed negative. Panchromatic films seem to have wider latitudes than orthochromatic emulsions. H. & 1). numbers for a film may be available and the meter employed utilizes Scheiner degrees or vice versa. For convenience I am listing below two tables, the first containing various films and their speeds in Scheiner decrees, and the second a comparison between Scheiner degrees and H. & I), numbers: Table of Film Speeds Daylight Mazda Agfa Fine-Grain Plenachrome 21 Agfa Superpan ----- 23 25 DuPont Orthochromatic 17 DuPont Panchromatic 18 DuPont Superior .24 DuPont Special Panchromatic 23 DuPont Micropan ---- 16 Eastman Kodak Orthochromatic 17 Eastman Panatomic 19 Eastman Kodak Panchromatic 17 Eastman Kodak Type 2 18 Eastman Kodak Supersensitive Panchromatic ---- 23 Eastman Kodak Verichrome 19 Gavaert Superchrome Express 21 Savaert Superchrome Express 21 Mimosa Extrema ---- 21 Perutz Orthochromatic 17 Perutz Persenso ---- 21 Selo Orthochromatic 19 Selo Panchromatic ---- 21 23 Voigtlander ------ 23 Scheiner Degrees and H. & D. Numbers Scheiner No. H. & D. No 10 56 11 72 12 91 13 117 14 150 15 190 16 240 1 7 308 18 390 19 500 20 27 25 18 22 21 22 26 20 21 22 23 24 25 26 27 28 29 30 31 32 636 800 1,050 1,300 1,700 2,100 2.700 3,500 4,400 5,600 7,200 'Moo 11,600 Despite the accuracy of exposure meters there is still a factor left to personal judgment — the color of the light. In the above table of emulsion speed provision is made for the speed of panchromatic films to mazda light. Daylight, however, varies in its chromatic characteristics. During noon it is what we may term normal. In the early morning or late afternoon it usually exhibits large quantities of red and yellow. Exposure meters measure the actinic strength of light in relation to its quantity, and not as to its color. A panchromatic and an orthochromatic film which have the same speed at noon will differ in speed at the mentioned times, when daylight contains large amounts of yellow and red. In this case the panchromatic emulsion will be of greater speed, due to its greater sensitivity to the longer wavelengths of light. With the use of a reliable meter the photographer should experience no difficulty in obtaining correct exposures. He should, however, guard against overexposure. Candid Photography: Of the types of photography to which the miniature camera has been a great stimulus, candid photography is perhaps the most outstanding. Since miniature cameras have gained popularity candid photography has also come into vogue. When considering newspapers candid photographs of celebrities engaged in certain activities always were prize catches. It was, however, difficult to obtain such photographs with large cameras. Many large newspapers now provide their staff men with miniature cameras and many of the candid "shots" seen in newspapers are made with baby cameras. Cameras like the Leica, Contax and Foth Derby which allow lenses to be interchanged, are best suited to this type of work. Besides the universal f:3.5 lens usually supplied with miniature cameras, a telephoto and speed lens are great helps in candid photography. ( Turn to Page 28) "ArtReeVes" Presents NEW TYPE Recording Lamp The EQUA-LITE More Light — Less Current Equalized Glow Bar J-[oll\wood Motion PicTure/^uipmenT0. |Td. 6A 5 NORTH MARTEL AVE CABLE ADDRESS ARTREEVES HOLLYWOOD, CALIFORNIA. USA Cables: ArtReeves Francais Espanol Deutsch Svenska PHONE: WYOMING 4501 Please mention The International Photographer when corresponding with advertisers.