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White Paper3 V5 Image Sensor Resolution vs. Pixel Size, Optical Format 13 defined as the ratio of the 12 4/3-type Imager signal from the sensor for a 4/3-type Image Sensors Four Thirds 2/3 inch Imager 11 System 1/2 inch Imager given illumination condition 10 and exposure time relative to in Digital Still Camera 4/3-type 9 the measured noise pro- duced from the sensor’s dark 8 Applications 4/3 Lens current and read-out circuit- 7 Resolving ry. While many photogra- Consumer Power Kodak KAF-5101CE 6 Market 5M pixel FF-CCD phers seem satisfied with the Resolution (M pixels) 5 image quality of today’s dig- Silicon Image Sensors - In the Digital Still Camera Marketplace 2/3" 4 ital cameras, Kodak’s 4/3- 1/2" ilicon image sensors have been paramount seeking higher performance and versatility , as well 3 Increasing Dynamic Range type image sensor , based on in establishing the wide market acceptance as improved value relative to traditional 35-mm dig- advanced full-frame CCD 2 Sof digital still photography. Kodak’s Image ital SLR cameras and lenses. 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 9.5 technology, delivers notice- Sensor Solutions division offers a broad array Pixel Size (µm) ably better images and estab- of image sensors (see Fig. 1) for a variety of Figure 6: Image sensor resolution vs. pixel size for various optical formats lishes a higher standard for digital imaging applications. Now a next- digital pictorial quality for generation format is being introduced that ding charge capacity, the Four Thirds System cam- professional photographers. will dramatically alter the market landscape. eras achieve 11 to 12 bits of dynamic range, equiv- Referred to as the “4/3-type” format, this 4:3 alent to the best digital SLR cameras in the profes- Kodak KAF-5101CE – A 5 Mega-pixel, aspect ratio format with a 22-mm photo- sional market today. 4/3-type Image Sensor graphic diagonal is targeted for the profes- The Kodak KAF-5101CE is a full-frame color CCD sional digital camera market segment. It will Photo-Sensitivity (charge-coupled-device) that has been specifically enable a revolutionary new generation of Many of today’s digital cameras are deficient in designed for Four Thirds System digital SLR cameras. high-quality, highly portable digital still cam- photo-sensitivity (effective ISO), performing relative- The KAF-5101CE incorporates 6.8-µm pixels with an eras for professional and advanced amateur ly poorly when capturing action photography in integral pigment color filter array and micro-lenses photographers. Figure 1: Kodak’s image sensors for performance poorly illuminated environments. To achieve a high- for superb color rendition and high photo-sensitivity. imaging applications. er effective ISO, the digital gain in these cameras is It delivers high image quality with low noise at frame Digital from the ground up, the Four Thirds System often increased and, with this, a commensurate rates of up to four (4) frames per second and an ISO unburdens camera makers from compatibility with level of noise is introduced into the images. Many range from ISO 100 to ISO 800. The KAF-5101CE is the traditional camera and lens formats from film- Common Optical Formats amateur photographers have been disappointed available with a companion timing generator chip based imaging, allowing them to optimize all the Digital still camera formats vary widely across the with the performance of their consumer digital that is specifically designed to optimize its perform- elements of digital camera design to achieve excel- different market segments. At the high end of the cameras in dimly lit gymnasiums, auditoriums or ance for digital still cameras. Together, these chips lent quality and high functionality with a more com- professional market segment, for example, digital other venues where lighting is insufficient or where augment Kodak’s broad line of image sensor solu- pact camera system. The power of the 4/3-type cameras based on so-called ‘645’ medium format motion is involved such as in sporting events. tions for performance imaging applications. imager comes from the synergies of its optimally focal plane use image sensors that are larger than However, with a Four Thirds System digital camera, matched Four Thirds System cameras and lenses. the 35-mm optical format (See Fig. 2); while 35- the effective ISO range is now 100 to 800 and can The Bottom Line Relative to today’s consumer cameras, the sensors mm and APS format imager sensors serve the pro- produce quality images in this diffi- Digital from the ground up, the Four Thirds System are large, high resolution devices with excellent fessional and advanced amateur markets, which uti- cult photographic space. It’s funda- creates a new category of digital still cameras with dynamic range, photo-sensitivity and signal-to-noise lize 35-mm digital SLR cameras. Consumer point mental physics: a larger imaging its combination of professional qual- performance. And, relative to the professional 35- and shoot cameras, in contrast, use much smaller area, combined with larger pixels ity and versatility at affordable mm format cameras, the new Four Thirds System silicon sensors such as 2/3 inch, 1/2 inch, 1/3 inch and new lenses specifically prices. Kodak offers a 5 mega-pixel digital SLR (single lens reflex) cameras offer a set of format and even smaller. Camera makers must designed for silicon sensors, 4/3-type image sensor solution that interchangeable lenses that will be inherently lighter choose an imager format based on the price target results in improved image quality lies at the heart of this exciting new weight, more compact and highly portable while for their camera, since the imager cost increases expected in professional digital digital SLR camera format for profes- providing professional quality images. with its size. While the precise geometries vary from SLR cameras. sionals and advanced amateurs. chip maker to chip maker, the most common for- The new 4/3-type image sensor offers professional mats are categorized in the table on the following Signal to Noise Ratio Figure 7: Kodak KAF-5101CE, 5 Mega- image quality with a smaller optical format, creating page. The 4/3-type image sensor, with new lenses pixel Full-Frame Color CCD Image Sensor A classical measure of image quality in digital pho- an exciting advantage for professional and designed to match the optical format, provides pho- tography is the signal-to-noise ratio of the image Image Sensor Solutions • (585) 722-4385 advanced amateur photographers. This new cate- tographers with the digital still camera performance sensor and camera system. This factor can be www.kodak.com/go/imagers gory of digital SLR cameras will appeal to those expected by professionals and advanced amateurs. imagers@kodak.com 35-mm Format Frame Imager Aspect Width Height Diagonal example, introduces an undesirable focal length Format Ratio H (mm) V (mm) (mm) magnification error, which effectively reduces the APS Format Imager Resulting Image 1/4” 4:3 3.2 2.4 4 photographic field of view for a given focal length 1/3” 4:3 4.8 3.6 6 (See Fig. 4). This creates a barrier to achieving wide 1/2” 4:3 6.4 4.8 8 angle photography with short focal length lenses 2/3” 4:3 8.8 6.6 11 that are designed for a full 35-mm format frame. 1” 4:3 12.8 9.6 16 While full 35-mm format image sensors can be used 1 4/3-type 4:3 17.8 13.4 22.3 to alleviate this problem, their higher cost results in APS 2 3:2 25.1 16.7 30.1 a camera price that may be prohibitive for advanced 35 mm 3:2 36.0 24.0 43.3 amateurs and even many professionals. Since 4/3- Figure 4: Photographic effect of an APS format imager used with 35-mm format camera with an f/3.0, 36x36 1:1 36.0 36.0 51.9 type image sensors and lenses are precisely 38-mm effective focal length lens 645 4:3 56.0 41.5 69.7 matched, there’s no magnification error introduced. The problem is confounded because the incident ISO, dynamic range and signal-to-noise perform- As such, no matter what type of lens is being used- angle is a strong function of the focal length and f- ance. It is a high resolution format from the first Footnotes: -wide angle, variable zoom or telephoto--the full 1. 4/3-type imager as described by Kodak KAF-5101CE image stop of traditional 35-mm lenses and, as such, generation on, with significant “head room” for sensor field of view presented to the user is usable photo- peripheral fading is dependent on each lens being going to much higher pixel counts and well beyond 2. Common ‘APS’ digital format: 23.7 mm (H) x 15.6 mm (V), graphic area. This provides professional and used. While large incident angles are not a problem the practical limitations of smaller format sensors. 28.4 mm diagonal advanced amateur photographers with wide angle for film-based photography (because silver-halide Kodak’s first 4/3-type image sensor, the KAF- photographic capability that is only commercially photo-sensitivity is relatively independent of inci- 5101CE, has 5-million 6.8 µm x 6.8 µm pixels and The 4/3-type Optical Format available in more expensive camera systems. dent light angle), it is highly desirable that the inci- renders exceptional detail while maintaining high The new 4/3-type format defines an optimal sensor dent angles be more normal (perpendicular) for sili- image quality; and 8 million, 10 million or even 12 size for its target market, Four Thirds System digital con image sensors, whose semiconductor architec- million pixels are not unrealistic in the years to come SLR cameras for the professional segment.
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