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Image sensor format

Image sensor format

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In digital photography
Digital photography
Digital photography is a form of photography that uses an array of light sensitive sensors to capture the image focused by the lens, as opposed to an exposure on light sensitive film...

, the image sensor format is the shape and size of the image sensor
Image sensor
An image sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices...

.

The image sensor format of a digital camera
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...

 determines the angle of view
Angle of view
In photography, angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view....

 of a particular lens when used with a particular camera. In particular, image sensor
Image sensor
An image sensor is a device that converts an optical image into an electronic signal. It is used mostly in digital cameras and other imaging devices...

s in digital SLR cameras tend to be smaller than the 24 mm x 36 mm image area of full-frame 35 mm cameras, and therefore lead to a narrower angle of view.

Lenses produced for 35 mm film
35 mm film
35 mm film is the film gauge most commonly used for chemical still photography and motion pictures. The name of the gauge refers to the width of the photographic film, which consists of strips 35 millimeters in width...

 cameras
Single-lens reflex camera
A single-lens reflex camera is a camera that typically uses a semi-automatic moving mirror system that permits the photographer to see exactly what will be captured by the film or digital imaging system, as opposed to pre-SLR cameras where the view through the viewfinder could be significantly...

 may mount well on the digital bodies, but the larger image circle
Image circle
The image circle, or circle of illumination, of a lens is the circular area in the image plane formed by the cone of light transmitted by the lens . Within this circle is the smaller circle for which image definition is acceptable, the circle of good definition ; however, some authors make no...

 of the 35 mm system lens allows unwanted light into the camera body, and the smaller size of the image sensor compared to 35 mm format results in cropping of the image compared to the results produced on the film camera. This latter effect is known as field-of-view crop; the format size ratio is known as the field of view crop factor, crop factor
Crop factor
In digital photography, a crop factor is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a...

 for short, or focal-length multiplier.

Sensor size and dynamic range


If all other performance aspects of a sensor's materials and fabrication techniques and amplification electronics are equal, a larger pixel size or pitch (i.e. lower resolution) sensor captures images with greater dynamic range
Dynamic range
Dynamic range, abbreviated DR or DNR, is the ratio between the largest and smallest possible values of a changeable quantity, such as in sound and light. It is measured as a ratio, or as a base-10 or base-2 logarithmic value.-Dynamic range and human perception:The human senses of sight and...

 than a smaller sensor. The larger pixel's area provides a larger collection trap or "well", in which photon
Photon
In physics, a photon is an elementary particle, the quantum of the electromagnetic interaction and the basic unit of light and all other forms of electromagnetic radiation. It is also the force carrier for the electromagnetic force...

-freed electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...

s can accumulate, giving rise to a higher ratio ("dynamic range") between the accurately recorded maximum and accurately recorded minimum number of incident photons striking each pixel area. The ratio between the accurate maximum and accurate minimum number of incident photons, that a sensor pixel can accurately report as having struck it over a given exposure interval, establishes an outer boundary for the theoretical signal to noise ratio (i.e. dynamic range) of the sensor for a given output resolution.

It is true that pixel size or area places an limit on the maximum number of photons that can be recorded by a given pixel. It is also true that various kinds of inherent fluctuations in weak signals limit the minimum number of photons a smaller pixel may accurately record. But one cannot predict the maximum ratio between accurate maximum and accurate minimum photon counts of a sensor, one cannot predict the sensor's dynamic range, merely by noting the "largeness" of a sensor pixel. Because the nature and efficiency of a sensor pixel's materials, and its fabrication technology, and surrounding optically significant overlays and amplification and recording systems, also further restrict the accuracy of both the largest and smallest photon counts.

It is easier for lower-resolution (larger pixel) sensor sites to achieve greater dynamic range, through the ease with which the physically larger sensor sites can accurately record larger maximum photon counts. But higher-resolution, smaller-pixel sensors may still have as good or better dynamic range, if they are fabricated and enhanced with supportive features and microlenses in such a way as to generally record their incident photon counts with greater accuracy.

Particularly significant in extending the dynamic range (ratio of accurate maximum to accurate minimum photon counts incident upon a sensor site) of higher-resolution sensors, are sensor designs and materials that more accurately record and output lower minimum photon counts at each sensor site.

Theoretically the dynamic range of smaller sensor sites could also increased by techniques for extending the maximum photon counts that a site could record during any given exposure interval. An example of such a theoretical technique for increasing the maximum number of photons a small site could record during a 10 millisecond exposure, would be arranging for the photon counts from a pixel to be recorded, and the pixel cleared of photons, at 1 millisecond intervals. At the end of the exposure interval the 10 different 1-millisecond photon counts could be summed, to provide a large photon count for the entire 10-millisecond interval. There are no commercial consumer cameras using this theoretical technique as of tody (2011).

Many DSLRs have sensor areas around 370 mm2, while many compact camera sensors have one-fifteenth the surface area: a standard 1/2.5" sensor has a surface area of 24.7 mm2. Thus, a typical DSLR will have a signal-to-noise ratio
Signal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...

 that is nearly 4 times higher than a typical compact digital camera, if the compact digital camera's sensor technology had as described at the top of this section identical fabrication technology, accuracy and efficiency:

When discussing output pixels that are displayed at constant magnifications, designing a lower-displayed-noise (higher dynamic range) sensor is easier as sensor size or pitch increases, i.e. as resolution is reduced for a given overall sensor size. In other words, it is easier to design a 6 megapixel sensor that will exhibit a low a signal-to-noise ratio when generating a 15 centimeter width image, as it is to fabricate a 24 megapixel sensor for displaying 30 centimeter wide images with the same apparent signal-to-noise ratio.

There is a natural tendency, on computer monitors, to examine images from both higher and lower pixel density sensors at the same per-pixel magnification. I.e. there is a tendency for image observers to view the output of higher resolution sensors at proportionately larger display sizes.

The casual viewing of higher-resolution images at larger display magnifications than the images from lower-resolution images tends to disproportionately magnify any image imperfections produced by the higher resolution sensors. This can give rise to the mistaken conclusion that any particular technology higher-resolution sensors necessarily has greater noise or less dynamic range than some different-technology lower-resolution sensor--if observers are not careful to ensure that the entire images from both sensors being compared are both displayed at an identical overall size.

Sensor size and diffraction limit


When imaging an infinitely small point in a scene, roughly speaking the "Airy disk" of a lens' image is the smallest circle of light that diffaction effects allow a perfect lens, at a given aperture or "F-stop", to throw onto a sensor to represent that point.

For monochromatic light, the diameter in micrometers of the Airy disk, produced by an aberration-free "perfect" lens, can be calculated as about 2.44 times the lens aperture or F-stop, further multiplied by the wavelength of light in micrometers. Thus when imaging "green" (550nm or 0.55um wavelength) light at F2.8, the Airy disk of a perfect lens is about (F2.8 x 2.44 x 0.55um)=4 micrometers in diameter. A 4-micrometer pixel pitch or spacing translates into a pixel density of 10 million pixels per square centimeter of sensor. Current (2011) DSLR (Digital Single Lens Reflex) and most MILC (Mirroless Interchangeable Lens Camera) sensors, typically with sensors of 2 square centimeters in size or greater, have pixel spacings that are larger than 4 micrometers. Whereas large-megapixel-count smaller sensors, of less than 2 square centimeter size, often have pixel spacings much smaller than the F2.8 green light Airy disk diameter.

At first glance it would seem pointless, in terms of overall increasing image resolution or clarity, to have a pixel spacing of less than 4 micrometers (at least when recording green light images from an F2.8 consumer-quality lens that is not entirely free of optical aberrations). I.e. one might think it pointless, in terms of increasing a sensor's image quality, to have greater sensor resolution than lens resolution.

However, much smaller sensor pixel pitches or spacing than the nominal Airy disk diameter are still useful for increasing image quality, for several reasons. The first is that the total resolution of a complex imaging system always increases whenever there is an increase in the resolution of any part of the chain of components in the system. This holds true even if one part of an imaging system has much greater resolution than another. Thus if we roughly approximated the theoretical resolution of a lens as being 100 lines per millimeter, and it was projecting its image onto a sensor with its own 200 lines per millimeter resolution, then the resolution of the entire system is the reciprocal of (1/lensResolution) plus (1/sensorResolution), or the reciprocal of (1/100)+(1/200), or roughly 66 lines per millimeter. Increasing the sensor resolution to 400 lines per millimeter, even though the sensor is already much higher resolution than the lens, would roughly increase the system's resolution to the reciprocal of (1/100)+(1/400), to 80 lines per millimeter.

A second smaller-pixel advantage, is that to perfectly accurately record red or blue color components of a 4 micrometer Airy disk of light on a sensor, a typical Bayer sensor camera needs to have 2 micrometer or less pixel spacing. That smaller spacing ensures there is at least one red or blue sensor pixel within every given Airy disk region. I.e. there are sensors for all colors underneath the image of every "point" in the scene. Indeed most current (2011) cameras are forced to use sophisticated "demosaicing" algorithms to estimate the full color of individual red, green and blue pixel locations, since each pixel is usually larger than half the diameter of the Airy disk region. This is true in the Bayer sensor color pixel pattern case. In the case of the rather rare Foveon-type cameras, or indeed with any sensor where there are sensors recording all colors at each pixel position, there is no need for pixel spacing less than 4 micrometers to accurately represent all the colors of a 4 micrometer disk of light.

A third benefit of pixels that are 2 micrometers apart or less, when imaging a 4 micrometer Airy disk, is that such densely packed pixels will not give rise to "aliasing" or sampling artifacts. Aliasing artifacts are false colors or false patterns that appear whenever a sensor is imaging features that are less than twice as large as the pixel spacing. Information theory predicts that there is no aliasing, hence no need for relatively expensive "anti aliasing filters", when the pixel spacing is less than half the diameter of the smallest disk of light hitting a sensor.

Another benefit of sensors having pixel spacings ever smaller than the Airy disk lens diffraction limit, is that there is ever smaller consequence in a consumer camera to having a quite large number of widely-scattered "bad" pixels. The camera manufacturer can supply a "map" of bad pixels with each camera, cost-effectively making use of slightly flawed sensors without noticeably harming their images.

The drive to ever-smaller pixels, i.e. ever-higher-megapixel sensors at a given sensor size, is often said to be largely based on marketing high pixel counts ("the pixel race"). However such broad dismissals of higher pixel density cameras are only considering nominal diffraction limits to sensor resolution, and do not account for the slightly increased resolution, increased color accuracy and reduced aliasing artifacts, and bad-pixel tolerance advantages of highest-pixel-density cameras.

Sensor size vs. lens size and depth of field


An important side effect of sensor size is to inevitably increase the size of the lens elements needed to produce an image of the larger size. Larger sensors require lenses with a larger angle of view, and/or need lenses with longer focal length, to produce a given image. The diameter of the exit pupil of a lens, which can be calculated as the focal length of the lens divided by its effective aperture number (such as F2.8), is a major determinant of depth of field. A 100 millimeter focal length lens set to aperture number "F10" will be working with a 10 millimeter diameter exit pupil. Depth of field is inversely proportional to lens exit pupil diameter.

At any given aperture, the inevitably longer focal length lenses required to produce an image of a given angle of view, on larger sensors, requires lenses with larger-diameter elements, which thus reduces the depth of field of that imaging system. See Depth of field vs. format size.

Smaller sensors necessitate shorter focal-length lenses to produce the same fields of view as lenses for larger sensor formats. The small-sensor shorter focal lengths work out to smaller lens exit pupil diameters (for the same aperture number or f-stop), so cameras with smaller sensors usually have deeper depth of field, for a given angle of view
Angle of view
In photography, angle of view describes the angular extent of a given scene that is imaged by a camera. It is used interchangeably with the more general term field of view....

 and F-stop.

Sensor size and telecentricity


Images incident on image sensors should be made up of rays hitting photoreceptors fairly close to perpendicular, for best detection efficiency and low pixel crosstalk. Lenses that produce such near-perpendicular incident angles, i.e. with rear elements farther away from the sensor for a given focal length, are said to be "image-side telecentric". As the lens designer moves a lens' rear elements farther away from the sensor, to achieve a more telecentric lens, they must package the lens elements in increasingly long and bulky housings.

Smaller pixel size, smaller sensors tend to be affected more noticeably by the non-perpendicularity of light coming from less-telecentric lenses. The result of this relatively high telecentricity sensitivity is that lenses for sensors that are half the size of a larger format, cannot always be designed with rear elements twice as close to the sensor. Consider a 40mm focal length lens for a 36mm width sensor, that might function without corner smearing or corner color shifts with a rear lens element that is 30mm away from the sensor. One might think that the rear element of 4mm focal length lens working with a 3.6mm width sensor could similarly be designed with a rear element that is just 3mm from the sensor.

However the net result of the increased telecentricity sensitivity of smaller sensors, is that the lenses that work well with them must have rear elements that are relatively farther away from the sensor than their smaller focal length suggests. Thus small-sensor lenses are housed in packages that are physically longer than one would predict from looking at the housings of lenses for larger sensors.

Film cameras did not have such sensitivity to the angle of light striking the film surface, since film is sensitive to light regardless of its direction or incident angle. That is possibly the main reason why 24x36 mm (full-frame) compact-zoom film cameras existed whose lenses (see here for an example), were much smaller (i.e. with closer rear elements) than typical digital zoom lenses for 24x36mm sensors.

Common image sensor formats



DSLR/MILC formats


Some professional DSLRs use full-frame sensors, equal to the size of a frame of 35 mm film.

Most consumer-level DSLRs and MILCs/EVILs use relatively large sensors, either around the size of a frame of APS
Advanced Photo System
Advanced Photo System is a film format for still photography first produced in 1996. It was marketed by Eastman Kodak under the brand name Advantix, by FujiFilm under the name Nexia, by AgfaPhoto under the name Futura and by Konica as Centuria.- Design :The film is 24 mm wide, and has three...

-C film, with a crop factor
Crop factor
In digital photography, a crop factor is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a...

 of 1.5-1.6; or 30% smaller than that, with a crop factor of 2.0 (this is the Four Thirds System
Four Thirds System
The Four Thirds system is a standard created by Olympus and Kodak for digital single-lens reflex camera design and development.The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different...

, adopted by Olympus and Panasonic).

On September 21st 2011, Nikon announced a new format, which they named CX. It will be adopted for the Nikon 1 camera system (Nikon J1 and V1 models). The sensor size of the CX format is 1" (2.7 crop factor).

As of September 2011 there is only one MILC model equipped with a very small sensor: it is Pentax Q. Its 1/2.3" sensor (5.62 crop factor) size is more typical of compact digital cameras. See Compact digital camera formats section below.

Many different terms are used in marketing and describing these sensor formats, including the following:
  • Full-frame digital SLR format, with sensor dimensions nearly equal to those of 35 mm
    135 film
    The term 135 was introduced by Kodak in 1934 as a designation for cartridge film wide, specifically for still photography. It quickly grew in popularity, surpassing 120 film by the late 1960s to become the most popular photographic film format...

     film (36 × 24 mm)
  • Canon's APS-H format for high-speed pro-level DSLRs (crop factor 1.3)
  • Leica's M8 and M8.2
    Leica M8
    The Leica M8 is the first digital camera in the rangefinder M series introduced by Leica Camera AG on 14 September 2006. It uses a 10.3-megapixel Kodak KAF-10500 CCD image sensor.As of 15/07/2011, the most recent firmware version is 2.014.-Features:...

     sensor (crop factor 1.33).
  • APS-C
    APS-C
    Advanced Photo System type-C is an image sensor format approximately equivalent in size to the Advanced Photo System "classic" size negatives...

     refers to a range of similarly-sized formats, including
    • Nikon DX format
      Nikon DX format
      The Nikon DX format is an alternative name used by Nikon corporation for APS-C image sensor format being approximately 24×16 mm. Its dimensions are about 2/3 those of the 35mm film format . The format was created by Nikon for its digital SLR cameras, many of which are equipped with DX-sized...

      , Pentax
      Pentax
      Pentax is a brand name used by Hoya Corporation for its medical-related products & services and Pentax Ricoh Imaging Company for cameras, sport optics , etc. Hoya purchased and merged with the Japanese optics company on March 31, 2008. Hoya's Pentax imaging business was sold to Ricoh Company, Ltd...

      , Konica Minolta
      Konica Minolta
      is a Japanese manufacturer of office equipment, medical imaging, graphic imaging, optical devices, and measuring instruments. It is headquartered in the Marunouchi Center Building in Marunouchi, Chiyoda, Tokyo, with a Kansai office in Nishi-ku, Osaka, Osaka Prefecture...

      /Sony α, Fuji (crop factor 1.5)
    • Canon entry-level DSLR formats (crop factor 1.6)
  • Foveon X3 format used in Sigma
    Sigma Corporation
    is a Japanese company founded in 1961, manufacturing cameras, lenses, flashes and other photographic accessories. All Sigma products are produced in the company's own Aizu factory in Bandai, Fukushima, Japan...

     SD-series DSLRs (crop factor 1.7)
  • Four Thirds System
    Four Thirds System
    The Four Thirds system is a standard created by Olympus and Kodak for digital single-lens reflex camera design and development.The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different...

     format (crop factor 2.0)
  • Nikon CX format used in Nikon 1 series
    Nikon 1 series
    The Nikon 1 series are high-speed mirrorless interchangeable-lens cameras. Announced on 21 September 2011, Nikon claims that it is "Nikon's most significant announcement since we introduced our first digital camera 14 years ago"...

     (crop factor 2.7)


Production costs for a full frame
Full frame
In cinematography, full frame refers to the use of the full film gate at maximum width and height for 35 mm film cameras. It is sometimes also referred to as silent aperture, full gate, or a number of other similar word combinations. It is the original gate size pioneered by William Dickson and...

 sensor can exceed twenty times the costs of an APS-C sensor. Only about thirty full-frame sensors can be produced on an 8 inches (20.3 cm) silicon wafer that would fit 112 APS-C sensors, and there is a significant reduction in yield due to the large area for contaminants per component. Additionally, the full frame sensor requires three separate exposures during the photolithography
Photolithography
Photolithography is a process used in microfabrication to selectively remove parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photomask to a light-sensitive chemical "photoresist", or simply "resist," on the substrate...

 stage, which requires separate masks and quality control steps. The APS-H size was selected since it is the largest that can be imaged with a single mask to help control production costs and manage yields.

Due to the ever-changing constraints of semiconductor fabrication
Semiconductor fabrication
Semiconductor device fabrication is the process used to create the integrated circuits that are present in everyday electrical and electronic devices. It is a multiple-step sequence of photolithographic and chemical processing steps during which electronic circuits are gradually created on a wafer...

 and processing, and because camera manufacturers often source sensors from third-party foundries, it is common for sensor dimensions to vary slightly within the same nominal format. For example, the Nikon
Nikon
, also known as just Nikon, is a multinational corporation headquartered in Tokyo, Japan, specializing in optics and imaging. Its products include cameras, binoculars, microscopes, measurement instruments, and the steppers used in the photolithography steps of semiconductor fabrication, of which...

 D3
Nikon D3
The Nikon D3 is a 12.1 megapixel professional grade full frame digital single lens reflex camera announced by the Nikon Corporation on 23 August 2007 along with the Nikon D300 DX format camera. The D3, along with the Nikon D3X, was a flagship model in Nikon's line of DSLRs, superseding the D2Hs...

 and D700
Nikon D700
The Nikon D700 is a professional grade full-frame digital single-lens reflex camera introduced by the Nikon Corporation in July 2008 and manufactured in Japan. It uses the same 12.1 megapixel "FX" CMOS image sensor as the Nikon D3, and is Nikon's second full-frame digital SLR camera...

 cameras' nominally full-frame sensors actually measure 36 × 23.9 mm, slightly smaller than a frame of 35 mm film. As another example, the Pentax
Pentax
Pentax is a brand name used by Hoya Corporation for its medical-related products & services and Pentax Ricoh Imaging Company for cameras, sport optics , etc. Hoya purchased and merged with the Japanese optics company on March 31, 2008. Hoya's Pentax imaging business was sold to Ricoh Company, Ltd...

 K200D
Pentax K200D
The Pentax K200D is a 10.2 megapixel digital single-lens reflex camera, announced on January 24, 2008 along with the higher-end K20D. It was discontinued in December 2008, giving it the distinction of being one of the shortest-lived DSLR cameras....

's sensor (made by Sony
Sony
, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

) measures 23.5 × 15.7 mm, while the contemporaneous K20D
Pentax K20D
The Pentax K20D and its clone, the Samsung GX-20, were 14.6 megapixel digital single-lens reflex cameras manufactured by Pentax that were announced on January 23, 2008. The K20D was available in the U.S...

's sensor (made by Samsung
Samsung Techwin
Samsung Techwin is a surveillance, aeronautics, optoelectronics, automations and defense company. It is a subsidiary of Samsung Group. The company employs 4720 employees and is headquartered in South Korea. Its totals sales in 2010 was 3,198 billion won....

) measures 23.4 × 15.6 mm.

Most DSLR image sensor formats approximate the 3:2 aspect ratio
Aspect ratio
The aspect ratio of a shape is the ratio of its longer dimension to its shorter dimension. It may be applied to two characteristic dimensions of a three-dimensional shape, such as the ratio of the longest and shortest axis, or for symmetrical objects that are described by just two measurements,...

 of 35 mm film. Again, the Four Thirds System
Four Thirds System
The Four Thirds system is a standard created by Olympus and Kodak for digital single-lens reflex camera design and development.The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different...

 is a notable exception, with an aspect ratio of 4:3 as seen in most compact digital cameras (see below).

Medium-format DSLR


The most common sensor size for medium-format digital cameras is approximately 48 millimetre, due to the widespread use of Kodak's 22-megapixel KAF-22000 and 39-megapixel KAF-39000
CCDs in that format. Phase one offers the P65+ digital back with Dalsa
Dalsa
Teledyne DALSA is a Canadian company specializing in the design and manufacture of specialized electronic cameras.The company was founded in Waterloo, Ontario, Canada in 1980 by imaging pioneer Dr. Savvas Chamberlain, a former Professor in Electrical Engineering at the University of Waterloo...

's 53.9 millimetre 16-bit sensor containing 60.5 megapixels
and Leica offers an "S-System" DSLR with a 45 millimetre sensor containing 37-megapixels. In 2010, Pentax
Pentax
Pentax is a brand name used by Hoya Corporation for its medical-related products & services and Pentax Ricoh Imaging Company for cameras, sport optics , etc. Hoya purchased and merged with the Japanese optics company on March 31, 2008. Hoya's Pentax imaging business was sold to Ricoh Company, Ltd...

 released the 40MP 645D medium format DSLR with a 44 millimetre sensor.

Compact digital camera formats


The sensor sizes of many compact digital cameras are expressed in terms of the non-standardized "inch" system, as approximately 1.5 times the length of the diagonal of the sensor. This goes back to the way image sizes of early video cameras were expressed in terms of the outside diameter of the glass envelope of the video camera tube
Video camera tube
In older video cameras, before the mid to late 1980s, a video camera tube or pickup tube was used instead of a charge-coupled device for converting an optical image into an electrical signal. Several types were in use from the 1930s to the 1980s...

. David Pogue
David Pogue
David Welch Pogue is an American technology writer, technology columnist and commentator. He is a personal technology columnist for the New York Times, an Emmy-winning tech correspondent for CBS News Sunday Morning, weekly tech correspondent for CNBC, and a columnist for Scientific American...

 of the New York Times states that "the actual sensor size is much smaller than what the camera companies publish — about one-third smaller." For example, a camera advertising a 1/2.7" sensor does not have a sensor with a diagonal of 0.37"; instead, the diagonal is closer to 0.26". Instead of "formats", these sensor sizes are often called types, as in "1/2-inch-type CCD." Most compact image sensors have an aspect ratio
Aspect ratio
The aspect ratio of a shape is the ratio of its longer dimension to its shorter dimension. It may be applied to two characteristic dimensions of a three-dimensional shape, such as the ratio of the longest and shortest axis, or for symmetrical objects that are described by just two measurements,...

 of 4:3. This matches the aspect ratio of the popular VGA, SVGA, and XGA display resolutions, allowing images to be displayed on most computer monitors without cropping.

, most compact digital cameras use 1/2.5" or 1/2.3" size sensors. Digicam
Digital camera
A digital camera is a camera that takes video or still photographs, or both, digitally by recording images via an electronic image sensor. It is the main device used in the field of digital photography...

s with the 1/2.5" sensor size include the Panasonic Lumix DMC-FZ18, Canon PowerShot A570 IS, Canon SD870 IS Digital ELPH (IXUS 860 IS), Canon Powershot SX210-IS, Sony Cyber-shot DSC-W80, Canon Powershot S5is, Sony Cyber-shot DSC-H7, Canon PowerShot TX1, Sony Cyber-shot DSC-H9, and Casio Exilim EX-V7. 1/2.3"-sensor digicams include the Kodak Easyshare M530, the Canon Powershot SX130 IS, the Fuji Finepix Z70, and the Nikon Coolpix S8100.

Many megazoom digicams use 1/2.33" sensors, including the Pentax Optio X90, the Olympus SP600uz, and the Kodak Z981. Additionally, some Sony digicams use a 1/2.4" sensor size, including the Sony Cyber-shot HX5V.

Compact cameras using sensors of nearly twice the area include Fujifilm Finepix s6000fd/ s6500fd (1/1.7"), Fuji Finepix F50fd (1/1.6") and Finepix F31fd (1/1.7"), Canon PowerShot G12 (1/1.7") and Powershot SD950 IS and S90/S95
Canon PowerShot S95
The Canon PowerShot S95 is a high-end 10.0 megapixel compact digital camera announced and released in 2010. It was designed as the successor to the Canon PowerShot S90 in the S series of the Canon PowerShot line of cameras....

(1/1.7"), Ricoh Caplio GX100 (1/1.75"), Nikon Coolpix P5000 (1/1.8") and Coolpix P7000 (1/1.7"), some Panasonic Lumix
Lumix
Lumix is Panasonic's brand of digital cameras, ranging from pocket point-and-shoot models to digital SLRs.Compact digital camera DMC-LC5 and DMC-F7 were the first products of the Lumix series released in 2001. They are equipped with Leica lenses....

 cameras like the DMC-LX3 and LX5 and the Olympus camera XZ-1(1/1.63"). The largest sensor currently equipping a compact camera should be the one (2/3") on board of Fuji's X-10 (announced on September 1, 2011).

Conversely, the sensors of camera phone
Camera phone
A camera phone is a mobile phone which is able to capture still photographs . Since early in the 21st century the majority of mobile phones in use are camera phones....

s are smaller than those of typical compact cameras, allowing greater miniaturization of the electrical and optical components. Sensor sizes of around 1/6" are common in camera phones, as well as in webcam
Webcam
A webcam is a video camera that feeds its images in real time to a computer or computer network, often via USB, ethernet, or Wi-Fi.Their most popular use is the establishment of video links, permitting computers to act as videophones or videoconference stations. This common use as a video camera...

s and digital camcorders. The recent Nokia N8
Nokia N8
The Nokia N8 is a Symbian^3 smartphone of the Nokia Nseries and Nokia's flagship device of 2010. It was released on 23 September 2010 at the Nokia Online Store before being released in markets around the world on 1 October 2010. The N8 features a 12 megapixel camera, a pentaband 3.5G radio and...

 has a sensor size of 1/1.83", however, having the largest sensor in a phone currently.

Table of sensor sizes


Inch-based sensor formats are not standardized. Originally, they were the outer diameters of the image tubes used in television cameras until the late 1980s. Exact dimensions may vary, but those listed are typical. The listed sensor areas span more than a factor of 1000 and are proportional
Proportionality (mathematics)
In mathematics, two variable quantities are proportional if one of them is always the product of the other and a constant quantity, called the coefficient of proportionality or proportionality constant. In other words, are proportional if the ratio \tfrac yx is constant. We also say that one...

 to the maximum possible collection of light and image resolution
Image resolution
Image resolution is an umbrella term that describes the detail an image holds. The term applies to raster digital images, film images, and other types of images. Higher resolution means more image detail....

 (same lens speed
Lens speed
Lens speed refers to the maximum aperture diameter, or minimum f-number, of a photographic lens. A lens with a larger maximum aperture is a fast lens because it delivers more light intensity to the focal plane, allowing a faster shutter speed...

 or aperture
Aperture
In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture of an optical system is the opening that determines the cone angle of a bundle of rays that come to a focus in the image plane. The aperture determines how collimated the admitted rays are,...

), but in practice are not directly proportional to image noise
Image noise
Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the sensor and circuitry of a scanner or digital camera...

 or resolution due to other limitations. See comparisons.

Type Diagonal (mm) Width (mm) Height (mm) Area (mm2) Stops
F-number
In optics, the f-number of an optical system expresses the diameter of the entrance pupil in terms of the focal length of the lens; in simpler terms, the f-number is the focal length divided by the "effective" aperture diameter...

 (Area)
Crop factor
Crop factor
In digital photography, a crop factor is related to the ratio of the dimensions of a camera's imaging area compared to a reference format; most often, this term is applied to digital cameras, relative to 35 mm film format as a reference. In the case of digital cameras, the imaging device would be a...

1/8" 2.00 1.60 1.20 1.92 -8.81 21.65
1/6" 3.00 2.40 1.80 4.32 -7.64 14.14
1/4" 4.00 3.20 2.4 7.68 -6.81 10.83
1/3.6" 5.00 4.00 3.00 12.0 -6.16 8.65
1/3.2" 5.68 4.54 3.42 15.50 -5.80 7.61
1/3" 6.00 4.80 3.60 17.30 -5.64 7.21
1/2.7" 6.72 5.37 4.04 21.70 -5.31 6.44
1/2.5" 7.18 5.76 4.29 24.70 -5.12 6.02
1/2.3" 7.70 6.16 4.62 28.50 -4.92 5.62
1/2" 8.00 6.40 4.80 30.70 -4.81 5.41
1/1.8" 8.93 7.18 5.32 38.20 -4.50 4.84
1/1.7" 9.50 7.60 5.70 43.30 -4.32 4.55
1/1.6" 10.07 8.08 6.01 48.56 -4.15 4.3
2/3" 11.00 8.80 6.60 58.10 -3.89 3.93
Super 16mm 14.54 12.52 7.41 92.80 -3.22 2.97
Nikon CX 15.86 13.20 8.80 116 -2.90 2.70
1" 16.00 12.80 9.60 123 -2.81 2.70
m4/3 · 4/3" (Four Thirds
Four Thirds System
The Four Thirds system is a standard created by Olympus and Kodak for digital single-lens reflex camera design and development.The system provides a standard that, with digital cameras and lenses available from multiple manufacturers, allows for the interchange of lenses and bodies from different...

)
21.60 17.30 13 225 -1.94 2.00
Sigma Foveon X3
Foveon X3 sensor
The Foveon X3 sensor is a CMOSimage sensor for digital cameras, designed by Foveon, Inc. and manufactured by National Semiconductorand Dongbu Electronics....

24.90 20.70 13.80 286 -1.60 1.74
Canon APS-C
APS-C
Advanced Photo System type-C is an image sensor format approximately equivalent in size to the Advanced Photo System "classic" size negatives...

26.70 22.20 14.80 329 -1.39 1.62
General APS-C
APS-C
Advanced Photo System type-C is an image sensor format approximately equivalent in size to the Advanced Photo System "classic" size negatives...

 / Nikon DX
Nikon DX format
The Nikon DX format is an alternative name used by Nikon corporation for APS-C image sensor format being approximately 24×16 mm. Its dimensions are about 2/3 those of the 35mm film format . The format was created by Nikon for its digital SLR cameras, many of which are equipped with DX-sized...

28.2-28.4 23.6-23.7 15.60 368-370 -1.23 1.52-1.54
Canon APS-H 33.50 27.90 18.60 519 -0.73 1.29
35mm Full-frame, Nikon FX 43.2-43.3 36 23.9-24.3 860-864 0 1.0
Leica S2 54 45 30 1350 +0.64 0.80
Pentax 645D 55 44 33 1452 +0.75 0.78
Kodak KAF 39000 CCD 61.30 49 36.80 1803 +1.06 0.71
Leaf AFi 10 66.57 56 36 2016 +1.22 0.65
Phase One P 65+, IQ160, IQ180 67.40 53.90 40.40 2178 +1.33 0.64

Bridging the gap in sensor sizes


Since 2005, there has been an increasing interest in producing medium-sized cameras with large sensors but without the mirror systems, and consequently the bulk, typical of DSLR camera bodies.

Manufacturers gradually responded to this interest. Epson, an early entrant, introduced the R-D1
Epson R-D1
The R-D1, announced by Epson in March 2004 and discontinued in 2007, was the first digital rangefinder camera. Manufactured by Cosina, which also builds the current Voigtländer and Zeiss Ikon cameras, the R-D1 and its successor, the Epson R-D1s , use Leica M-mount lenses or earlier Leica screw...

, a digital rangefinder using the Leica M mount. Other companies followed suit, by introducing similar cameras that focus electronically rather than manually (such as Olympus, with its PEN series; Panasonic, with its G and GF series; Sony, with its Nex series; Samsung, with its NX series). Such cameras might overall look like compact digital ones, with at least two notable differences: a sensor in most cases of the size found in digital SLRs, and interchangeable lenses.
The latter feature, though, is now to be found in at least one small-sensor compact camera as well (Pentax Q, announced on June 2011).


Until recently, a large gap existed in sensor size between digital compact cameras on one side and DSLRs/MILCs on the other. Compact cameras were all equipped with sensors smaller than 1/1.6" (48.5 mm2), whereas 4/3" (225 mm2) was the smallest sensor to be found on DSLRs/MILCs. One noticeable exception was – long ago – Olympus E-10 (a large, semi-professional hybrid camera announced in the year 2000 and equipped with a comparably tiny 2/3" sensor).
The main reason for such a gap was portability: large sensors imply the need of bulky lenses (see previous chapter). That's why MILC cameras equipped with large sensors tend to show a marked disproportion between their tiny bodies and their imposing lens systems (their zoom objectives especially).


The size gap was at last bridged by camera models announced in September 2011. On the compact side of the gap, a very large (for a compact) 2/3" (58.1 mm2) sensor equips the high-end compact announced by Fuji on Sep. 1st 2011 (Fuji X10). At the same time, on the other (DSLR/MILC) side of the collapsed chasm, Nikon announced (in September 2011 as well) the Nikon 1 system, built around a new sensor format they named 'CX' (13.2mm x 8.8mm, that is roughly 1" in the inch system).

How much this new breed of MILCs will, in addressing the lens-bulk issue, compromise the typical advantages associated with larger sensors (such as high-ISO performance) has yet to be seen. In any case, such format additions (the 'CX' especially) have now eliminated the previous gap in sensor sizes: the crop-factor difference now existing between the largest compact camera sensor (2/3", 3.9 crop factor) and the smallest MILC sensor (1", 2.7 crop factor) is about half the one previously existing between 1/1.6" and 4/3" sensors.

See also

  • Full-frame digital SLR
  • Sensor size and angle of view
  • 35 mm equivalent focal length
    35 mm equivalent focal length
    In photography, the 35 mm equivalent focal length is a measure that indicates the angle of view of a particular combination of a camera lens and film or sensor size...

  • Film format
    Film format
    A film format is a technical definition of a set of standard characteristics regarding image capture on photographic film, for either stills or movies. It can also apply to projected film, either slides or movies. The primary characteristic of a film format is its size and shape.In the case of...


External links