#17_kantor_en_0802:#17_kantor_en_0802.qxd 21.05.2009 20:48 Page 143
New data on minerals. M.: 2003. Volume 38 143
UDC 549(084.12)
PHOTOGRAPHING MINERALS
Boris Z. Kantor
For art or technical photographing minerals in non professional conditions, high quality of medium magni- fications can be ensured by means of miniature single lens reflex (SLR) cameras of general use and ordinary photographic materials. To apply long focus macro lenses and avoid diaphragm excessive closing is recom- mended. To reproduce morphological features of a mineral, flexible and multi functional artificial lighting is necessary. For negatives, daylight film in combination with light conversion filter is recommended. Adequate reproducing of mineral complicated color involves accurate matching of color temperatures and selection of light sources, preferably halogen low power cold light lamps, corresponding the given combi- nation of photographic material and color conversion filter. 7 color photos, 2 references.
Photography expands appreciably our tographer’s taste, competence, and miner- no tion of the mineral kingdom. In skillful alogical interests, let us define technical hands, even a plain shatter may be lifted, in preconditions of mineral successful pho- its information and esthetic value, from the tography under these «amateur» condi- waste bin up to the level of museum speci- tions. men. An experienced photographer would A mineral photo should be sufficiently never disregard those fragments, minia- sharp. Viewing, from the usual reading dis- tures, and unpretentious petty crystals that tance (25–30 cm), a picture up to 15 or are usually ignored by museums and col- 20 cm in size, a person with normal eyesight lectors. At the same time, a large specimen discerns not more than 8 or 10 lines per mm attracting general admiration and exposed (400–500 dpi). Accordingly demanded res- in its own separate showcase would hardly olution of a miniature (24 x 36 mm) nega- look equally spectacular on its small or tive is 50–60 lines per mm (2500–3000 medium size photo. Photography also gives dpi) maximum. This is fairly achievable full scope for any kind of interesting with the present time photographic lenses art experiments with minerals. and medium speed films (ISO 100–200). Provided a well tooled up professional Technically perfect pictures can be made, studio is available, the technique of photo- so, with an ordinary miniature SLR camera, graphing minerals differs little from the including any one of the amateur class, and ordinary close up photography (Scovil, ordinary photographic materials of general 1996). However, mineralogist and photog- use. rapher professions combine only seldom in A medium format camera even enables the same person. More often, a mineralo- creating a «reserve» of resolution for an gist – specialist or hob by ist– has no occasion of manufacturing larger magnifi- access to the expensive special cameras as cation. However, popular roll film cameras well as studio lamps and other professional (e.g., Pentacon Six or Exacta 66) have com- equipment. To illustrate a book or a paper parably massive mirrors which entails or simply to picture minerals occasionally harmful vibrations during the process of for his own pleasure, he is obliged to exposure. As a result, the resolution is accommodate to the homely schedule of appreciably diminished and so the medium the so called pop photography: picturing format advantage reduces to nothing. A with a general use camera with succeeding good tripod diminishes vibration but can- processing and printing in a minilab. not eliminate it entirely. It is less noticeable Setting aside purely pictorial problems, on condition of short enough (not more whose solving depends entirely on the pho- than 1/100–1/180 s) or long enough (not #17_kantor_en_0802:#17_kantor_en_0802.qxd 21.05.2009 20:48 Page 144
144 New data on minerals. M.: 2003. Volume 38
less than 2–3 s) shutter speed, which is, The possibility of the lens aperture to be however, not always accessible. Another closed down at least to f=32 is advisable. way is to expose by switching the light on Ho wever, closing down should not be over- for the metered time after the shutter has used. Sometimes, it contradicts the pictori- been previously opened in darkness. The al task; in addition, it affects adversely ima- latter may entail, however, a shift of color in ge quality. According to our data, the reso- the red side because of the light source lution of Canon EF as well as Sigma EX thermal lag. macro lenses is maximal at f=8 and drops So the balance of advantage should be by 20–25 per cent at f=22, and even by lain with miniature cameras. On condition 40 per cent for the Sigma EX 2,8/50 macro of using a tripod, the vibration in this case lens. is inconspicuous. In addition, some minia- To choose the type of light sources is a ture cameras are provided with the option primary task. In photographic sense, min- of shutter release delay after the mirror has erals are fairly complicated objects. This been lifted, which gives additional assur- implies the use of not less than three or four ance. autonomous light sources supplemented At the same time, the larger format is with reflecting cards of white paper and preferable for slides, as they need, in this aluminium foil. The gleams of faces and the case, no magnification to be viewed. whole light pattern are very much sensitive Minerals are mostly photographed in to the illuminator positions. This implies a close up regime, i.e. with magnifications literally precision setup of light. It can be up to 1:1, sometimes greater. As the camera achieved on condition the illuminators are standard lens cannot be focused from the enough mobile. demanded short distances, one lengthens it By this reason, the «non controlled» su- with an extension tube or bellows or pro- nlight only finds a limited use, and so elec- vides with a close up lens. However, both tronic flash without pilot light. The tung- mentioned entail deterioration in the image sten low powered lamps are mostly used, as quality, since the camera standard lens is they do not provoke photographer’s weari- corrected for «infinite» distance and does ness of too intensive light and heat radia- not, in the mentioned case, answer its pur- tion that is also ruinous for some minerals pose. Essentially better images can be pro- like native sulfur or realgar. Mounted on duced with a macro lens as its optical sys- miniature stands, the lamps may be easily tem is specially corrected for close up dis- moved along the surface of the table, an tances. In particular, not too expensive improvised shooting stage. A miniature lenses of the Sigma EX macro series are remote control station with individual tog- noteworthy; they are put out for all the gle switches for illuminators would enable basic SLR cameras of modern generation photographer to set up lighting not draw- (Canon, Nikon, Minolta, and Pentax) and ing away from the camera viewfinder. produce high quality images. Adequate reproducing of mineral com- For mineral photography, a macro lens plicated and whimsical colors is a most with focal length about 100 mm is the best. urgent problem. It facilitates well the illusion of third In the process of minilab printing, color dimension and perspective, is accommoda- rendition errors of a negative can be cor- tive in operation, and, compared with rected to a small degree only; besides, this short focus lens, less liable to light diffrac- is only possible after the draft copies have tion in the diaphragm hole. been made and studied. As to color slides, Despite of the common opinion, the use they cannot be corrected at all. To correct of a long focus lens does not entail dimin- color completely is not always possible ishing of the depth of field. According to even by means of editing files obtained by calculations, the depth of field at close up scanning original photographs. So it is very photography is proportionate to important to avoid errors when taking pic- tures or, at least, to minimize them. The f(M+1)/M2, pledge of success is the proper choice of film, light filter, and light source types with where f is diaphragm number and M is matched color parameters: image magnification. Therefore the depth 5 5 of field does not depend on the focal 10 /Tl – Мlf=10 /Тf, length. #17_kantor_en_0802:#17_kantor_en_0802.qxd 21.05.2009 20:48 Page 145
Photographing Minerals 145
where Tl, Тf – color temperatures, men, with no pattern, spot, and texture. A Kelvin (K), of light sources and film, Мlf – neutral gray background is universal. A filter conversion degree, decamired. highlight spot on the background behind The film choice is only confined to two the photographed object would «lift» it and types balanced either for day (sun) light or intensify volume illusion. A photo printer tungsten light with color temperatures, file printout of gradual passage from white accordingly, 5500 K and 3400 K. The choice to dark gray color, with the dark side up, is of light conversion filters is also limited. a successful solution. The background Purplish blue filters are usually used with should be placed at a sufficient distance to conversion degree either 12 or 15 de ca - avoid shadow falling from the specimen. mired (marked as B12, B15 or Wratten 80B, All the modern miniature SLR cameras Wratten 80A). On the other hand, the mar- are provided with automatic exposure me- ket assortment of lamps is fairly rich, and, tering. Having chosen the aperture priority furthermore, they are much cheaper than function and set up the proper diaphragm light conversion filters. So it is reasonable number, one lets the camera to set up the to select lamp type matching one or two proper shutter speed. On the condition of film — filter type fixed combinations. light shadow contrast being sufficiently Slides are usually taken on a reversible evened, the option of integral (polyseg- film for the light of incandescent lamps ment) metering should be selected. (tungsten light). As to negative films for When viewing a specimen, one turns it tungsten light, they belong to the category absent mindedly with various sides to him- of relatively expensive materials of narrow self, lingering at some details of especial assortment and are intended mainly for interest, and thereby a cumulative portrait studio photography. At the same three dimensional visual image is being time, color correct rendition can be also formed in one’s consciousness. The pho- achieved with daylight film on condition tographer’s task is to imitate this image on that the lamps are selected correctly and the picture plane emphasizing, at the same the light is conversed with the proper filter. time, either detail important for the given Unfortunately, lamp manufacturers do object, e.g., etching form, twinning seam, not indicate, as a rule, their color tempera- or face striation. For all this, only two picto- tures. According to our data, they are di- rial means are actually available: specimen verse within fairly wide bounds. The light orientation and lighting setup. It is useful tem peratures of the majority of miniature to study the specimen previously under the halogen lamps are at the level of 2700– desk lamp in order to outline pictorial solu- 2800 K, like domestic low powered lamps. tion and select the object pole position and More promising are the halogen lamps of directions of main and accessory lighting. «cold light». In particular, «Radium» Co- In the process of this procedure, it is better mpa ny (Germany) produces miniature ha - to view the specimen by single eye only, logen lamps for 12 V and 50 W that can be likewise camera does. On the shooting matched satisfactorily with daylight film stage, the illuminators and reflecting and 12B or 15B conversion filter. So do, as screens should be set up one after another well, home produced mirror photolamps of to light up, successively, the entire shape, the ZK 220–250 type for 220 V and 250 W. brilliance and sculpture of faces etc. A To diminish fatiguing radiation, the latter’s reflecting screen of sufficiently large size voltage can be reduced for the period of can partly imitate the source of diffused light setup (which is inadmissible for halo- light, which may be problematic for the gen lamps). home studio. At the final stage, the general For the lack of a special light—shadow contrast should be regulat- light colorimeter, color temperature of a ed. A powerful tubular halogen lamp light source may be estimated even in directed a sufficient distance from the front domestic conditions (Ka n tor, 1999). Of would do for this aim. course, obtained data should be verified by It is very important to check the speci- means of control picturing of chromatic men cleanness. Being left on its surface, scale and colored and color free objects dirt, dust, fingerprints will inevitably be (malachite, crocoite, quartz, etc.). visible on the picture. The background – a sheet of paper, ca r - dboard, cloth – should be even, of subdu- All the illustrations have been taken with ed color, congruous with that of the speci- Canon EOS 50E camera with Sigma EX #17_kantor_en_0802:#17_kantor_en_0802.qxd 21.05.2009 20:48 Page 146
146 New data on minerals. M.: 2003. Volume 38
2.8/105 mm macro lens and References light conversion filter Schneider 80B, using the mirror two second blocking option, on 1. Scovil, J.A.Photographing Minerals, Fos- Kodak ProFoto 100 and Fuji Superia 200 sils, and Lapidary Materials. 1996. Tu- films; the lighting with «Radium» miniature cson: Geoscience Press. halogen lamps 12 V 50 W. 2. Kantor, B.Z. What is the Color of Your Light? //Khimiya i zhizn’ – XXI vek, Author’s specimens and photos. July, 1999. pp. 62—63.