Amateur Photographer & Cinematographer (1936)

Ih[ amateur photographer a A CINEMATOGRAPHER o screen at the last meeting of the Royal Photographic Society, thought to be very helpful by suggesting that ordinary light was like rounded poles, whereas polarised light was like a lath, and a lath could go through the bars of a gate, and a rounded pole could not. It rather reminds us of the explanation given in one of Mr. H. G. Wells’s mystery stories as to how a man was able to see things which were happening on the other side of the earth. “ Nothing,” said the materialistic common-sense person, “ nothing can alter the fact that the other side of the earth is so many thousands of miles away.” “ Ah,” said the scien¬ tist, “ but you have forgotten ; two points on a sheet of paper may be a yard apart, but they may be in close contact by the simple ex¬ pedient of bending the paper over.” That is how the Einsteinists always get us. But, whatever the theory of polarisation, the pola screen seems destined to make its mark on photography. Mr. Davies exhibited a number of pictures taken with and without the screen. With crossed pola screens, for example, unwanted texture of surfaces can be completely removed. This is particularly useful in making a photographic copy of oil paintings. It removes the oblique reflections from glass and water, showing the detail beyond. The screen can bring about a darkening of the sky when required, a thing already possible, of course, in mono¬ chrome work by the interposition of a colour filter, but in colour work March qth, 1936 such a thing would be out of the question, and here the screen may prove very valuable. The range of transmission of the screen, we are told, is from 4,000 to 7,000 Angstrom units. The increase of exposure if the screen is used over the camera lens is about three times. If the screen were a perfect polariser it would pass half the incident light, but it is only about 67 per cent perfect, and therefore the light ia reduced to about one-third. On the important question of price, Mr. Davies said it would be comparable with ordinary photographic filters — perhaps three or four times more, but not as excessively high asany one having regard to its remark¬ able properties and possibilities might imagine. The A mateur Photographer” E XPOSURE T ABLE — March EVERY MONTH a brief exposure table will be provided for the assistance of our readers in their practical work. A glance at the current approximate exposures as here given will serve as a reliable guide for most purposes. The subjects will be varied to suit the time of year. The following exposures will serve as a working guide for any fine day during the month, between the hours of 10 in the morning and 2 in the afternoon, with the sun shining, but not necessarily on the subject. Stop used, f/8. The exposure should be doubled if the sun is obscured, or if stop f/11 is used. For f/16 give four times the exposure. For f/5.6 give half. From 9 to 10 a.m. or from 2 to 3 p.m., double these exposures. From 7 to 9 a.m. or from 3 to 5 p.m., treble them. Subject. Ordinary. Medium. Rapid. Extra Rapid. Ultra Rapid. Open seascapes and cloud studies . . 1/20 sec. 1/30 sec. 1/60 sec. 1/80 sec. 1/100 sec. Open landscapes with no very heavy shadows in foreground, shipping studies or seascapes with rocks, beach scenes, snow scenes with no heavy foreground . . 1/12 * * 1/18 y y 1/35 y y 1/50 y y 1/60 yy Ordinary landscapes and landscapes with snow, open river scenery, figure studies in the open, light buildings, wet street scenes 1/5 y y 1/8 y y 1/15 y * 1/20 y y 1/25 yy Landscapes in fog or mist, or with strong foreground, well-lighted street scenes . . 1/4 * * 1/6 y y 1/12 y y 1/15 y y 1/20 yy Buildings or trees occupying greater portion of picture . . 1/2 y y 1/4 y y 1/5 y y 1/6 y y 1/-' y y Portraits or groups taken out of doors, not too much shut in by buildings . . 11 y y 1 y y 1/2 y y 1/3 y y 1/4 y y Portraits in well-lighted room, light sur¬ roundings, big window, white reflector . . 5 secs. 4 secs. 2 secs. 11 y y 1 y y As a further guide we append a list of some of the best-known makes of plates and films on the indicate the speeds referred to above. The hypersensitive panchromatic plates and Ultra Rapid. Agfa, Special Portrait. „ Isopan ISS Film. „ Super-speed Film. „ Isochrom Film. „ Ultra Special. Barnet, Press and Super Press. „ XL Super-speed Ortho. „ Soft Panchromatic. „ Studio Fast. „ Ultra Rapid. Eastman, Par Speed Cut Film. „ S.S. Cut Film. ,, S.S. Pan. Film. Gevaert, Super Sensima. „ Sensima Fast. „ Sensima Ortho. „ Super Chromosa. „ Roll Films and Packs. Ilford, Golden Iso-Zenith. Ilford, Iso-Zenith. Kodak, Verichrome Film. Agfa Iso Rapid Chromo. „ Hypersensitive Pan. „ Super Sensitive Pan. „ Roll Film. Plates and Films. Film. Barnet, S.R. Pan. „ Portrait Film (Ortho „ Panatomic. Marion, Record. „ Studio Ortho. Fast). Ensign, Roll Film. ,, Monarch. „ Iso Record. Gevaert, Filtered Ortho. „ Press. Selo, Selochrome Roll Film and „ Chromosa. „ S.S. Ex. Sens. Film Pack. „ S.R. „ Zenith Ex. Sens. „ Selo. Pan. Roll Film. „ Regular Cut Film. „ S.G. Pan. Voigtlander, IUustra Film. Ilford, Auto. Filter. Illingworth, Fleet. Wellington, Anti-screen. „ S.R. Pan. „ Super Fleet. ,, X Press. Zeiss Ikon, Pemox Roll Film ,, Pan. Film. „ Super Fleet Ortho. „ Rapid Chromatic. Imperial, Non-filter (new series). „ Pan. Fleet. and Packs. Imperial, S.S.S. Press Ortho. Extra Rapid. „ Eclipse Pan. B. „ S.S. Ortho. „ Eclipse. Agfa, Chromo. Kodak, Roll Film and Film Pack. „ Eclipse Ortho Soft. „ „ Isolar. Pathe, Roll Film. „ Eclipse Soft. „ Extra Rapid. Selo, Roll Film. „ Eclipse Ortho. „ Isolar. Zeiss Ikon, Roll Film and Film „ Eclipse Pan. Soft. „ Iso Rapid. 190 Pack. market. They have been divided into groups, which approximately films require less exposure than the ultra-rapid. Rapid. BaRnet, S.R. ,, Self-screen Ortho. Ilford, Screen Chromatic. „ S.R. „ Commercial Ortho Film. Imperial, Non-Filter. „ S.R. „ S.R. Ortho. Kodak, Cut Film. Medium. Ilford, Empress. „ Chromatic. Ordinary. Barnet, Ordinary. Gevaert, Ordinary. Ilford, Ordinary. „ Rapid Process Pan. Imperial, Ordinary. Pan. Process. 6