Design Concept and Technologies of New High Speed Color Reversal Film

―309― J. Soc. Photogr. Sci. Technol. Japan, Vol. 64, No. 5, 2001

技術レポート Design Concept and Technologies of New High Speed Color Reversal Film

新しい高感度カラーリバーサルフィルムの設計の考え方と技術

Yasushi IRIE*, Tomoyuki NAKAYAMA* and Hiroshi SIMAZAKI*

入江康志*・中山知是*・嶋崎博*

Abstract In February 2001, a new high-speed color reversal film was introduced into the Japanese market. Based on an analysis of the Japanese domestic reversal film market, the design concept of this film was established as an easy-to-use and reliable film for amateur users in nature photography and in casual picture taking. To realize this design concept, special attention was paid to photographic speed and to the stability of color balance because these would have a particular effect on the easy-to-use of amateur users. This reversal film has not only high speed and stable color balance, but also natural color reproduction and crisp gradation in the highlight region. A new silver halide technology, named Precisely Divided Function (PDF) crystal technology, and new yellow coupler technology were developed to achieve these features.

要旨我々は,2001年2月に新しい高感度カラーリバーサルフィルムを国内において発表した。このフィルムは,ネイチャーフォトやカジュアルな写真撮影を楽しむアマチュアユーザーの方を対象に,使い易く,

信頼性の高いフィルムの提供が目的であり,日本国内のリバーサルフィルム市場動向の分析に基づいて設計された。設計においては,アマチュアユーザーの使い易さに大きく影響する感度と色バランスの安定性について,特に注意が払われた。また,このリバーサルフィルムの特徴は,高感度かつ安定な色バランスだけではなく,自然な色再現性とハイライト領域の抜けのよい階調を有していることにもある。これらの特徴を達成するために,Precisely Divided Function crystal technologyと名付けられた新しいハロゲン化銀乳剤技術と新しいイエローカプラー技術が開発された。

Key words: Color reversal film キーワード:カラーリバーサルフィルム

high picture quality characteristic of color rever- 1. Introduction sal films. In addition, throughout the past dec- Since the close of the 1970s, the domestic color ade, reversal films have shown a remarkable reversal film market has grown steadily, increas- improvement in performance. ing at a rate of about 5% per year, as seen in Fig. In appreciation of these trends, Konica 1. This increase stems from the growing num- Chrome SINBI, a new series of color reversal ber of amateur photographers attracted to the films designed to attract reversal film users, was

Received 22th. Julv 2001, Accepted 29th, August 2001平成13年7月22日受付,平成13年8月29日受理 * CM R&D Center, Image Capture Division, Consumer Imaging Company, Konica Corporation No. 1 Sakura-machi, Hino-shi, Tokyo 191-8511 コニカ株式会社コンシューマーイメージングカンパニーイメージキャプチャー事業部CM開発センター〒191-8511東京都日野市さくら町1番地 ―310― Yasushi IRIE et al J. Soc. Photogr. Sci. Technol. Japan

Fig. 2 Change of amount of color reversal films by usage from 1993 to 1997 in Japan. The source is "Weekly Photographic Report Fig. 1 Trend of amount of 35 mm color reversal films (Japan)". Reversal film usage could be classified shipped in Japan". to three types, namely "Medical and business use", "Professional use" and "Amateur use" . Only "Amateur use" was increased from 1993 to 1997 introduced. The concept of our approach can , be seen in one of those films, Konica Chrome and this accounted for a half in 1997. SINBI200 High Quality color reversal film, with an ISO speed of 200, described here. 2. Market trends Sales of reversal film in Japan have risen continuously over many years, even during the recent and remarkable spread of digital photography. Reversal film use is of three types: medical and business use, professional use, and amateur use. Actually, the medical and business use, as well as the professional consumption, of reversal film in fact decreased from 1993 to 1997, as seen in Fig. 2, probably due to the Fig. 3 Change of reversal film users' ratio from 1993 to spread of digital photography. In contrast, 1997 in Japan. growth in the amateur sector has more than The source is "Weekly Photographic Report made up for this, and total consumption has (Japan)". "Amateur users' ratio has grown to account for half in 1997. increased. As seen in Fig. 2 and Fig. 3, both amateur use and amateur users' ratio accounted for only about one third of the totals for 1993, but by 1997 they had grown to account for half. Today, amateur use dominates reversal films. According to our market research, reflected in Fig. 4 (a), the ratio of people of over 60 years of age, the so-called 'active-age' users, is very high among amateur users, accounting for roughly half, a conclusion supported by official research reports1). The proportional size of this genera- (a) Ratio of users by age (b) Ratio of subjectsof picturetaking tion in Japan will increase continuously in the Fig. 4 Segmentation of amateur users by age (a) and of near future, and we can assume that how these subject of picture taking (b) according to our market research. The ratio of people of over 60 people spend their significant number of leisure years of age accounts for roughly half of whole hours will be of central concern to them. users. And nature is dominant subject of picture Assuming that social circumstances continue as taking. Design Concept and Technologies of New High Speed Vol.64, No.5, 2001 Color Reversal Film ― 311― they have, this generation well may contribute to a further increase in reversal film users. As seen in Fig. 4 (b), nature is the major subject area of photography for amateur users. We believe that these photographers seek attrac- tive, high quality pictures in nature photography, and we know that such photos can be provided by color reversal film. Color reversal film is characterized by the superior features for which * silver halide photography has historically been Exchange rate: ••115/US $ known in comparison with other picture taking Fig. 5 An example of "heavy and expensive equipment is materials, characteristics such as superior needed". Lower speed film needs higher sensitiv- graininess and sharpness, and excellent stereo- ity of picture taking system if pictures must be graphic impression. taken at the same exposure time. High speed To summarize these market trends, 1) the lens, which has smaller F number (left side in the figure), is generally weight and expensive as domestic reversal film market exhibits a continu- compared with larger F number lenses (right side ous growth unhampered even by the advent of in the figure). The prices are based on our digital photography, 2) amateurs, especially research in 2000. those over 60, already dominate color reversal film use, and continue to increase, and 3) nature photography is their preferred photographic sub- A second comment often heard from this ject. group is that picture-taking results are often unintended. For example, many amateur users 3. The design concept are familiar with a phenomenon such as taking Color reversal film use enjoys both familiarity picture using a blue filter in shady or cloudy and popularity among many amateur users. conditions. The color balance of gray shifts Still, not all aspects of reversal film photography toward blue and results in a lack of the yellow have proven advantageous to these users. component under these conditions, because a For example, some comment that heavy, fluctuation of color balance against color tem- expensive equipment is sometimes needed in perature occurs. Grays and greens then look order to use color reversal film. It is generally unnatural, and the stereographic impression of more difficult to obtain satisfactory picture qual- such photos is wanting. Another example is ity with higher speed of film, so the amateur yellow color reproduction. Some current rever- color reversal film user has mainly used ISO100 sal films have reproduce yellow poorly, so that, or slower speed films when doing nature photog- for example, the yellow of flowers such as chry- raphy. Unfortunately, lower speed restricts the santhemum and rape blossoms are reproduced time, location, and situation under which such with an unnatural orange cast. Again, the photography can be done, unless a high speed answer to these problems would be a reversal lens and/or a tripod are used in compensation, as film with stable color balance and faithful color seen in Fig. 5, and this makes physical and eco- reproduction. nomic demands on the users to which they are To respond to complaints such as these, it was particularly sensitive. Adding to this problem adopted that the design concept of a color rever- is the fact that, for many amateur users, part of sal film for amateur users, especially 'active-age' photography's attraction is the variety of equip- amateur users, was easy-to-use and reliable qual- ment such as lenses and filters that can be em- ity. ployed to achieve particular effects. These 4. The features of Konica Chrome SINBI200 items benefit many users, but they also bring a High Quality color reversal film decrease in system sensitivity that must be dealt with. The answer to these problems would be a In keeping with the research we had done, the high-speed color reversal film with excellent features we sought in Konica Chrome SINBI200 picture quality. High Quality color reversal film were high speed ―312― Yasushi TRW et al J. Soc. Photogr. Sci. Technol. Japan

(IS0200) and low fluctuation against color tem- seen schematically in the change of gray color perature. balance against color temperature in Fig. 6, High speed makes picture taking easier, and SINBI200 offered a smaller fluctuation when low fluctuation against color temperature pre- compared with our former film, SINRA. vents unintended picture-taking results. Both But beyond these concerns, another factor is features give users more chances and fields of important in the design of a color reversal film, picture taking. Our new film not only achieved namely color emphasis. Fig. 7 is a map of pic- high speed with its ISO200 rating, but also, as ture quality regarding gradation and color emphasis, and it indicates film usage at each position. In recent years, loud color emphasis, in the upper right corner of Fig. 7, has become common in color reversal films. Nature photos taken with a color emphasis in this region are very striking and perhaps even beautiful, but they can also be somewhat unnatural. Princi- pally, loud color emphasis brings instability of gray balance and a large fluctuation of color balance against color temperature. We thought it would be better to avoid this and to bring stability to gray balance because this would widen the range of natural picture- taking situations under which amateur users Fig. 6 Change of color balance at density =1 against could rely upon their film to give them good color temperature change relative to the balance results. Therefore, a medium color emphasis in about 5500K. Upper figure is a color triangular diagram having axes of blue (B), green (G), red was designed into SINBI200. At the same time, (R), yellow (Y), magenta (M), cyan (C) color crisp gradation in the highlight region was directions. Lower figure indicates color tempera- designed to make pictures clear without the need ture. The sun near 5500K means that this color for loud color emphasis. temperature corresponds to sunny condition. Natural color reproduction gives an impres- Cloud near 6700K corresponds to cloudy condition, and tree near 7500K corresponds to shadow condi- sion which users truly see and can almost feel, as tion. The circles indicate the positions of reflected in Fig. 7. For many years, high-speed SINBI200, and the triangles SINRA, which is color reversal film was regarded as having poor Konica's former film. As the color temperature color reproduction when compared with lower becomes higher, the color balance shifts to blue. speed films. But even with a muted color emphasis, the color reproduction of SINBI200 is nearly identical to our former IS0100 color reversal film, SINRA, as seen in Fig. 8. We also gave close attention to faithful color reproduction. Fig. 9 is the sum of differences in hue between original colors and reproduced colors for blue, green, red, yellow, magenta, and cyan, and SINBI200 can be seen to have more faithful color reproduction as compared with our former films. But Fig. 10, which is a magnified yellow region of a chromatically diagram, shows Fig. 7 Map of picture qualities from points of view of that the lemon yellow reproduced by SINBI200 gradation and color saturation (color emphasis). lies directly on the line of lemon yellow color The region enclosed by broken line would be used reproduction. by many amateur users for nature photos. SINBI200 could be in the region of "natural repro- Finally, high speed color reversal films have duction", and Konica's former films, SINRA and been typically known for their soft gradation in R-200 are also located for comparison. highlight regions, which often resulted in a lack Design Concept and Technologies of New High Speed Vol.64, No.5, 2001 Color Reversal Film ―313―

Fig. 10 Magnified chromatically diagram for yellow region. Broken line shows the line of lemon yellow hue, and therefore lemon yellow color reproduction on this line means faithful lemon

Fig. 8 Chromatically diagram. Solid line indicates yellow color reproduction. Color reproduction color reproduction area of SINBI200. Dotted line of lemon yellow by SINBI200 is on this line. is of Konica's former ISO100 reversal film, SINRA. Broken line is of Konica's former IS0200 reversal film, R-200. The color reproduction area of SINBI200 is as the same as that of ISO100 speed film, SINRA and is fairly larger than that of R-200.

Fig. 11 Characteristic curves of green sensitive layers. Dark line is for SINBI200, and thin line is for Konica's former film SINRA. Two curves were shifted to have same relative log H position at density= 1. SINBI200 has crispy gradation in highlight region indicated by dotted circle line as compared with SINRA.

Fig. 9 Comparison of sum of differences in hue between original colors and reproduced colors for blue, green, red, yellow, magenta and cyan in pares the characteristic curve of the green sensi- chromatically diagram. Larger the sum tive layers of SINBI200 with those of our former becomes, larger the differences between original film, SINRA, emphasizing the importance we color and reproduced color become. The sum of attach to the clearness of nature photos. SINBI200 is small compared with Konica's former To summarize, the major features of reversal film, SINRA and R-100. SINBI200 are 1) high speed (IS0200), 2) low fluctuation against color temperature, 3) natural of clarity and images unsuitable for nature color reproduction, 4) crisp gradation in the photos. But SINBI200's crisp gradation in the highlight region, and 5) special attention to the highlight region makes for clear images despite faithful reproduction of lemon yellow. Bal- the film's muted color emphasis. Fig. 11 com- ances were optimized among three important ―314― Yasushi IRIE et al J. Soc. Photogr. Sci. Technol. Japan

Table 1 The features and the related technologies of SINBI200

Fig. 13 Schematic figure of Precisely Divided Functions Fig. 12 Schematic triangle of color reversal film prop- Crystal. The grain has cubic shape and mostly erties of color saturation, faithful color reproduc- (100) surface. The portion of the front corner is tion and stability of color balance. Faithful cut off in parallel with (111) surface in order to color reproduction and stability of color balance show the internal structure of the grain. are made much in the design of SINBI200, because the concept of SINBI200 is easy-to-use film for nature and casual photos. coupler were introduced which contribute to natural color reproduction and faithful yellow color reproduction. elements of color reversal film, namely color High-performance color reproduction was emphasis, stability of color balance, and color achieved mainly through the design of gradation reproduction, so that excellent nature photos can and through spectral sensitivity controlled by be taken easily, as seen in Fig. 12. filter dyes and coupler dyes, while the interimage effect by iodide was effectively suppressed. 5. The technologies Combined, these technologies brought color bal- The features discussed above were achieved ance that is stable against fluctuation in picture by the new technologies seen in Table 1. taking and/or processing condition, as, for High speed was achieved by two silver halide example, color temperature. technologies. One is tabular grain technology PDF crystal technology and new yellow cou- with excellent grain size distribution; these pler technology deserve a bit more detail in their grains are mainly used in the highest sensitive description. emulsion layer of the blue, green, and red sensi- 5.1 Precisely Divided Function crystal tech- tive units. The second silver halide technology nology Precisely Divided Function (PDF) crystal tech- PDF crystals are cubic silver iodobromide nology; these grains are mainly used in the crystals containing at least three phases, as seen middle and lower sensitive emulsion layers. in Fig. 13. The outer layer functions to control This technology also contributed to the crisp the development speed of the grain. By optim- gradation. izing the silver iodide content in the layer, crisp A new magenta filter dye and new yellow gradation is obtained, and controlling the outer Design Concept and Technologies of New High Speed Vol.64, No.5, 2001 Color Reversal Film ―315―

achieve crisp gradation and high sensitivity. 5.2 New yellow coupler technology A new yellow coupler was developed and introduced into blue sensitive emulsion layers in order to achieve more natural yellow color reproduction5). The yellow dye from this new yellow coupler has an absorption spectrum which is slightly blue-shifted when compared with the dye from our former coupler, as seen in Fig. 14. This has achieved better reproduction of lemon yellow. 6. Summary While these technologies were also applied to

Fig. 14 Absorption spectra of new coupler dye used in Konica Chrome SINBI100 High Quality color SINBI200 and Konica's former coupler dye. reversal film, SINBI200 perhaps saliently pres- The new dye has blue shifted absorption spec- ents these technologies. SINBI200 is well- trum compared with the former dye. suited to nature and to casual picture taking due to its high speed, natural color reproduction, layer helps obtain picture clarity when the grains crisp highlight gradation, and stability of color are used in lower sensitive emulsion layer. balance. These features combine to bring ama- The second layer from the crystal surface teur users easy use and dependable results under functions to increase the sensitivity of the crys- wide-ranging conditions. PDF crystals, and a tal. This layer usually has the highest iodide new yellow coupler are especially responsible content in the grain and is positioned near the for the advances found in SINBI200. surface in order to obtain high sensitivity. The References mechanism of sensitization is speculated as fol- lows: this layer may produce and have many 1) Photo market, 21-265 (2000) shallow electron traps which store photoexcited 2) T. Nakayama et al., Paper C19 in The International East-West Symposium on the Factors Influencing electrons and prevent recombination of these The Efficiencyof Photographic Imaging (1988) electrons and the holes in spectral sensitizing 3) F. Granzer, ibid., Paper Cl dyes. Some models of the shallow electron trap 4) Y. Suga, Fujifilm Research & Development, 44, 7 formation have been proposed2-4). Generally (1999) high iodide content on the crystal surface leads 5) S. Ikesu et al., Paper P15 in Annual Meeting of Society of Photographic Science and Technology of to soft gradation, so it is important to control Japan (2001) each layer distincty in order to simultaneously