Thursday, 10 April 2008
Wednesday, 9 April 2008
Tuesday, 8 April 2008
Monday, 17 March 2008
Saturday, 19 January 2008
full-frame
A full-frame digital SLR is a digital single-lens reflex camera fitted with an image sensor that is the same size as a 35 mm negative.[1][2] This is in contrast to cameras with smaller sensors, typically of a size equivalent to APS-C-size film, much smaller than a full 35 mm frame. As of 2007 the majority of digital cameras, both compact and SLR models, use a smaller-than-35 mm frame, as it is easier and cheaper to manufacture imaging sensors at a smaller size. Historically, the earliest digital SLR models, such as the Kodak DCS-100, also used a smaller sensor.
When a lens designed for a full frame is mounted on a smaller-than-full-frame camera, only the center of the imaging area is captured. The edges are cropped off, which has the effect of zooming in on the center section of the imaging area. The ratio of the size of the captured image to the size of the full-frame 35-mm format is known as the "crop factor" or "focal-length multiplier", and is typically in the range 1.3–2.0 for non-full-frame digital SLRs.
Nikon, which introduced their first full frame camera, the D3, in 2007, refers to the format as the FX format, as opposed to the APS-C format, which they refer to as the DX format.SLR is a digital single-lens reflex camera fitted with an image sensor that is the same size as a 35 mm negative.[1][2] This is in contrast to cameras with smaller sensors, typically of a size equivalent to APS-C-size film, much smaller than a full 35 mm frame. As of 2007 the majority of digital cameras, both compact and SLR models, use a smaller-than-35 mm frame, as it is easier and cheaper to manufacture imaging sensors at a smaller size. Historically, the earliest digital SLR models, such as the Kodak DCS-100, also used a smaller sensor.
When a lens designed for a full frame is mounted on a smaller-than-full-frame camera, only the center of the imaging area is captured. The edges are cropped off, which has the effect of zooming in on the center section of the imaging area. The ratio of the size of the captured image to the size of the full-frame 35-mm format is known as the "crop factor" or "focal-length multiplier", and is typically in the range 1.3–2.0 for non-full-frame digital SLRs.
Nikon, which introduced their first full frame camera, the D3, in 2007, refers to the format as the FX format, as opposed to the APS-C format, which they refer to as the DX format.
When a lens designed for a full frame is mounted on a smaller-than-full-frame camera, only the center of the imaging area is captured. The edges are cropped off, which has the effect of zooming in on the center section of the imaging area. The ratio of the size of the captured image to the size of the full-frame 35-mm format is known as the "crop factor" or "focal-length multiplier", and is typically in the range 1.3–2.0 for non-full-frame digital SLRs.
Nikon, which introduced their first full frame camera, the D3, in 2007, refers to the format as the FX format, as opposed to the APS-C format, which they refer to as the DX format.SLR is a digital single-lens reflex camera fitted with an image sensor that is the same size as a 35 mm negative.[1][2] This is in contrast to cameras with smaller sensors, typically of a size equivalent to APS-C-size film, much smaller than a full 35 mm frame. As of 2007 the majority of digital cameras, both compact and SLR models, use a smaller-than-35 mm frame, as it is easier and cheaper to manufacture imaging sensors at a smaller size. Historically, the earliest digital SLR models, such as the Kodak DCS-100, also used a smaller sensor.
When a lens designed for a full frame is mounted on a smaller-than-full-frame camera, only the center of the imaging area is captured. The edges are cropped off, which has the effect of zooming in on the center section of the imaging area. The ratio of the size of the captured image to the size of the full-frame 35-mm format is known as the "crop factor" or "focal-length multiplier", and is typically in the range 1.3–2.0 for non-full-frame digital SLRs.
Nikon, which introduced their first full frame camera, the D3, in 2007, refers to the format as the FX format, as opposed to the APS-C format, which they refer to as the DX format.
Canon 30D (1.6 crop) image overlayed on a 5D (full frame) image. showing the difference between a full-frame and an APS-C sensor
Sunday, 13 January 2008
Polaroid FOR RB
There are three types of Polaroid available: -
667 - 3000 ISO Black and White - http://www.polaroid.com/service/filmdatasheets/3_4/667fds.pdf
669 - 80 ISO Colour
http://www.polaroid.com/service/filmdatasheets/3_4/669fds.pdf
690 - 125 ISO Colour
http://www.polaroid.com/service/filmdatasheets/3_4/690fds.pdf
Polaroid is the name of a type of synthetic plastic sheet which is used to polarise light.
The original material, patented in 1929 (U.S. Patent 1,918,848 ) and further developed in 1932 by Edwin H. Land, consists of many microscopic crystals of iodoquinine sulphate (herapathite) embedded in a transparent nitrocellulose polymer film. The needle-like crystals are aligned during manufacture of the film by stretching or by applying electric or magnetic fields. With the crystals aligned, the sheet is dichroic: it tends to absorb light which is polarised parallel to the direction of the crystal alignment, but transmits light which is polarised perpendicular to it. The resultant electric field of an electromagnetic wave (such as light) determines its polarisation. If the wave interacts with a line of crystals as in a sheet of polaroid, any varying electric field in the direction parallel to the line of the crystals will cause a current to flow along this line. The electrons moving in this current will collide with other particles and re-emit the light backwards and forwards. This will cancel the incident wave causing little or no transmission through the sheet. The component of the electric field perpendicular to the line of crystals however can cause only small movements in the electrons as they can't move very much from side to side. This means there will be little change in the perpendicular component of the field leading to transmission of the part of the light wave polarized perpendicular to the crystals only, hence allowing the material to be used as a light polariser.
A building seen through polaroid sunglassesThis material, known as J-sheet, was later replaced by the improved H-sheet Polaroid, invented in 1938 by Land. H-sheet is a polyvinyl alcohol (PVA) polymer impregnated with iodine. During manufacture, the PVA polymer chains are stretched such that they form an array of aligned, linear molecules in the material. The iodine dopant attaches to the PVA molecules and makes them conducting along the length of the chains. Light polarised parallel to the chains is absorbed, and light polarised perpendicular to the chains is transmitted.
Another type of Polaroid is the K-sheet polariser, which consists of aligned polyvinylene chains. This polariser material is particularly resistant to humidity and heat.
Polaroid sheets are used in liquid crystal displays, optical microscopes and sunglasses.
The intensity of light passing through a Polaroid polariser is described by Malus's law.
Polaroid is also used as a trade name for a variety of products sold by licensees of the Polaroid Corporation, including consumer electronics, sunglasses based on Polaroid polarisers, and instant-print photographic film and cameras.
667 - 3000 ISO Black and White - http://www.polaroid.com/service/filmdatasheets/3_4/667fds.pdf
669 - 80 ISO Colour
http://www.polaroid.com/service/filmdatasheets/3_4/669fds.pdf
690 - 125 ISO Colour
http://www.polaroid.com/service/filmdatasheets/3_4/690fds.pdf
Polaroid is the name of a type of synthetic plastic sheet which is used to polarise light.
The original material, patented in 1929 (U.S. Patent 1,918,848 ) and further developed in 1932 by Edwin H. Land, consists of many microscopic crystals of iodoquinine sulphate (herapathite) embedded in a transparent nitrocellulose polymer film. The needle-like crystals are aligned during manufacture of the film by stretching or by applying electric or magnetic fields. With the crystals aligned, the sheet is dichroic: it tends to absorb light which is polarised parallel to the direction of the crystal alignment, but transmits light which is polarised perpendicular to it. The resultant electric field of an electromagnetic wave (such as light) determines its polarisation. If the wave interacts with a line of crystals as in a sheet of polaroid, any varying electric field in the direction parallel to the line of the crystals will cause a current to flow along this line. The electrons moving in this current will collide with other particles and re-emit the light backwards and forwards. This will cancel the incident wave causing little or no transmission through the sheet. The component of the electric field perpendicular to the line of crystals however can cause only small movements in the electrons as they can't move very much from side to side. This means there will be little change in the perpendicular component of the field leading to transmission of the part of the light wave polarized perpendicular to the crystals only, hence allowing the material to be used as a light polariser.
A building seen through polaroid sunglassesThis material, known as J-sheet, was later replaced by the improved H-sheet Polaroid, invented in 1938 by Land. H-sheet is a polyvinyl alcohol (PVA) polymer impregnated with iodine. During manufacture, the PVA polymer chains are stretched such that they form an array of aligned, linear molecules in the material. The iodine dopant attaches to the PVA molecules and makes them conducting along the length of the chains. Light polarised parallel to the chains is absorbed, and light polarised perpendicular to the chains is transmitted.
Another type of Polaroid is the K-sheet polariser, which consists of aligned polyvinylene chains. This polariser material is particularly resistant to humidity and heat.
Polaroid sheets are used in liquid crystal displays, optical microscopes and sunglasses.
The intensity of light passing through a Polaroid polariser is described by Malus's law.
Polaroid is also used as a trade name for a variety of products sold by licensees of the Polaroid Corporation, including consumer electronics, sunglasses based on Polaroid polarisers, and instant-print photographic film and cameras.
Tuesday, 8 January 2008
Effective film speed/Exposure/Development
Effective film speed
The ISO standard for black and white negative film, ISO 6:1993, uses chemistry, development technique, and development criteria that often have little relation to those used in practical photography (the same was true for previous standards). Consequently, the Zone System practitioner often must determine the speed for a particular combination of film and developer; the speed determination is commonly based on Zone I. Although the method for determining speed for the Zone System is conceptually similar to the ISO method for determining speed, the Zone System speed is an effective speed rather than an ISO speed
Exposure
A dark surface under a bright light can reflect the same amount of light as a light surface under dim light. The human eye would perceive the two as being very different but a light meter would measure only the amount of light reflected, and its recommended exposure would render either as Zone V. The Zone System provides a straightforward method for rendering these objects as the photographer desires. The key element in the scene is identified, and that element is placed on the desired zone; the other elements in the scene then fall where they may. With negative film, exposure often favors shadow detail; the procedure then is to
Visualize the darkest area of the subject in which detail is required, and place it on Zone III. The exposure for Zone III is important, because if the exposure is insufficient, the image may not have satisfactory shadow detail. If the shadow detail is not recorded at the time of exposure, nothing can be done to add it later. Carefully meter the area visualized as Zone III and note the meter’s recommended exposure. Adjust the recommended exposure so that the area is placed on Zone III rather than Zone V. To do this, use an exposure two stops less than the meter’s recommendation.
Development
For every combination of film, developer, and paper there is a “normal” development time that will allow a properly exposed a negative to give a reasonable print. In many cases, this means that values in the print will display as recorded (e.g., Zone V as Zone V, Zone VI as Zone VI, and so on). In general, optimal negative development will be different for every type and grade of paper.It often is desirable for a print to exhibit a full range of tonal values; this may not be possible for a low-contrast scene if the negative is given normal development. However, the development can be increased to increase the negative contrast so that the full range of tones is available. This technique is known as expansion, and the development usually referred to as “plus” or “N+”. Criteria for plus development vary among different photographers; Adams used it to raise a Zone VII placement to Zone VIII in the print, and referred to it as “N + 1” development.Conversely, if the negative for a high-contrast scene is given normal development, desired detail may be lost in either shadow or highlight areas, and the result may appear harsh. However, development can be reduced so that a scene element placed on Zone IX is rendered as Zone VIII in the print; this technique is known as contraction, and the development usually referred to as “minus” or “N-”. When the resulting change is one zone, it is usually called “N - 1” development.It sometimes is possible to make greater adjustments, using “N + 2” or “N - 2” development, and occasionally even beyond.Development has the greatest effect on dense areas of the negative, so that the high values can be adjusted with minimal effect on the low values. The effect of expansion or contraction gradually decreases with tones darker than Zone VIII (or whatever value is used for control of high values).Specific times for N+ or N- developments are determined either from systematic tests, or from development tables provided by certain Zone System books
The ISO standard for black and white negative film, ISO 6:1993, uses chemistry, development technique, and development criteria that often have little relation to those used in practical photography (the same was true for previous standards). Consequently, the Zone System practitioner often must determine the speed for a particular combination of film and developer; the speed determination is commonly based on Zone I. Although the method for determining speed for the Zone System is conceptually similar to the ISO method for determining speed, the Zone System speed is an effective speed rather than an ISO speed
Exposure
A dark surface under a bright light can reflect the same amount of light as a light surface under dim light. The human eye would perceive the two as being very different but a light meter would measure only the amount of light reflected, and its recommended exposure would render either as Zone V. The Zone System provides a straightforward method for rendering these objects as the photographer desires. The key element in the scene is identified, and that element is placed on the desired zone; the other elements in the scene then fall where they may. With negative film, exposure often favors shadow detail; the procedure then is to
Visualize the darkest area of the subject in which detail is required, and place it on Zone III. The exposure for Zone III is important, because if the exposure is insufficient, the image may not have satisfactory shadow detail. If the shadow detail is not recorded at the time of exposure, nothing can be done to add it later. Carefully meter the area visualized as Zone III and note the meter’s recommended exposure. Adjust the recommended exposure so that the area is placed on Zone III rather than Zone V. To do this, use an exposure two stops less than the meter’s recommendation.
Development
For every combination of film, developer, and paper there is a “normal” development time that will allow a properly exposed a negative to give a reasonable print. In many cases, this means that values in the print will display as recorded (e.g., Zone V as Zone V, Zone VI as Zone VI, and so on). In general, optimal negative development will be different for every type and grade of paper.It often is desirable for a print to exhibit a full range of tonal values; this may not be possible for a low-contrast scene if the negative is given normal development. However, the development can be increased to increase the negative contrast so that the full range of tones is available. This technique is known as expansion, and the development usually referred to as “plus” or “N+”. Criteria for plus development vary among different photographers; Adams used it to raise a Zone VII placement to Zone VIII in the print, and referred to it as “N + 1” development.Conversely, if the negative for a high-contrast scene is given normal development, desired detail may be lost in either shadow or highlight areas, and the result may appear harsh. However, development can be reduced so that a scene element placed on Zone IX is rendered as Zone VIII in the print; this technique is known as contraction, and the development usually referred to as “minus” or “N-”. When the resulting change is one zone, it is usually called “N - 1” development.It sometimes is possible to make greater adjustments, using “N + 2” or “N - 2” development, and occasionally even beyond.Development has the greatest effect on dense areas of the negative, so that the high values can be adjusted with minimal effect on the low values. The effect of expansion or contraction gradually decreases with tones darker than Zone VIII (or whatever value is used for control of high values).Specific times for N+ or N- developments are determined either from systematic tests, or from development tables provided by certain Zone System books
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