The f-number of an optical system such as a camera lens is the ratio of the systems focal length to the diameter of the entrance pupil. It is a number that is a quantitative measure of lens speed. It is known as the ratio, f-ratio, f-stop. The f-number is commonly indicated using a hooked f with the format f/N, the f-number N or f# is given by, N = f D where f is the focal length, and D is the diameter of the entrance pupil. It is customary to write f-numbers preceded by f/, which forms a mathematical expression of the pupil diameter in terms of f and N. Ignoring differences in light transmission efficiency, a lens with a greater f-number projects darker images, the brightness of the projected image relative to the brightness of the scene in the lenss field of view decreases with the square of the f-number. Doubling the f-number decreases the brightness by a factor of four. To maintain the same photographic exposure when doubling the f-number, the time would need to be four times as long. Most lenses have a diaphragm, which changes the size of the aperture stop.
The entrance pupil diameter is not necessarily equal to the aperture stop diameter, a 100 mm focal length f/4 lens has an entrance pupil diameter of 25 mm. A200 mm focal length f/4 lens has a pupil diameter of 50 mm. The 200 mm lenss entrance pupil has four times the area of the 100 mm lenss entrance pupil, a T-stop is an f-number adjusted to account for light transmission efficiency. The word stop is sometimes confusing due to its multiple meanings, a stop can be a physical object, an opaque part of an optical system that blocks certain rays. In photography, stops are a used to quantify ratios of light or exposure. The one-stop unit is known as the EV unit. On a camera, the setting is traditionally adjusted in discrete steps. Each stop is marked with its corresponding f-number, and represents a halving of the light intensity from the previous stop. This corresponds to a decrease of the pupil and aperture diameters by a factor of 1/2 or about 0.7071, each element in the sequence is one stop lower than the element to its left, and one stop higher than the element to its right
Digital zoom is a method of decreasing the apparent angle of view of a digital photographic or video image. It is accomplished electronically, with no adjustment of the cameras optics, in the former case, digital zoom tends to be superior to enlargement in post-processing, because the camera may apply its interpolation before detail is lost to compression. In the latter case, resizing in post-production yields results equal or superior to digital zoom, modest camera phones use only digital zoom and have no optical zoom at all. Usually cameras have an optical lens, but apply digital zoom automatically once its longest optical focal length has been reached. Professional cameras generally do not feature digital zoom, Digital zoom use the center area of the optical image to enlarge the image. By reducing the MP image size, using digital zoom can be done without image deterioration and some cameras has Undeteriorated image mode or at least has Image deterioration indicator. The table below give Undeteriorated zoom limit for some MP image size of a camera with Optical zoom 24x and Digital zoom 4x for its maximum capability, Note.
The table above has shown that from 3MP jumps directly too much too VGA and this camera has no option of 2MP and 1. 3MP, but other cameras have it. When using digital zoom for video, the camera can take up to 382. 6x magnification in VGA with Deteriorated image quality, but because video take multiframes per second, so between Deteriorated image quality and Undeteriorated image quality will be not much different. Nowadays cameras usually have iZoom with usually additional magnification 2x of its optical zoom, the iZoom use only center of the lens and not make any interpolation to original full resolution, so it save its good images quality in reduced resolution. The terms among camera manufacturers are “Smart Zoom”, “Safe Zoom”, there is camera with digital zoom 7. 2x and smartzoom with approximately 30x total zoom for 7MP from 16MP total resolution and 144x total zoom for VGA 640x480. Some photographers purposefully employ digital zoom for the low fidelity appearance of the images it produces.
This community thinks that poor quality photographs imply the carelessness of the photographer and thus, the notion that it is possible to achieve authenticity through pre-meditated carelessness inspires Lo-fi music. Image scaling Teleside converter - a secondary lens made for fixed lenses that increases the focal length, uses as a filter Zoom lens
Factors considered may include unusual lighting distribution, variations within a camera system, non-standard processing, or intended underexposure or overexposure. Cinematographers may apply exposure compensation for changes in angle or film speed. Most DSLR cameras have a display whereby the photographer can set the camera to either over or under expose the subject by up to three f-stops in 1/3rd stop intervals. Each number on the scale represents one f-stop, decreasing the exposure by one f-stop will halve the amount of light reaching the sensor, the dots in between the numbers represent 1/3rd of an f-stop. In photography, some cameras include exposure compensation as a feature to allow the user to adjust the automatically calculated exposure, camera exposure compensation is commonly stated in terms of EV units,1 EV is equal to one exposure step, corresponding to a doubling of exposure. Exposure can be adjusted by changing either the lens f-number or the exposure time, if the mode is aperture priority, exposure compensation changes the exposure time, if the mode is shutter priority, the f-number is changed.
If a flash is being used, some cameras will adjust it as well, the earliest reflected-light exposure meters were wide-angle, averaging types, measuring the average scene luminance. When measuring a scene with atypical distribution of light and dark elements, or an element that is lighter or darker than a middle tone. For example, a scene with predominantly light tones often will be underexposed and that both scenes require the same exposure, regardless of the meter indication, becomes obvious from a scene that includes both a white horse and a black horse. A photographer usually can recognize the difference between a horse and a black horse, a meter usually cannot. When metering a white horse, a photographer can apply exposure compensation so that the horse is rendered as white. Many modern cameras incorporate metering systems that measure scene contrast as well as average luminance, in scenes with very unusual lighting, these metering systems sometimes cannot match the judgment of a skilled photographer, so exposure compensation still may be needed.
An early application of compensation was the Zone System developed by Ansel Adams. Developed for black-and-white film, the Zone System divided luminance into 11 zones, with Zone 0 representing pure black, the meter indication would place whatever was metered on Zone V, a medium gray. The meter indication, remains Zone V, the Zone System is a very specialized form of exposure compensation, and is used most effectively when metering individual scene elements, such as a sunlit rock or the bark of a tree in shade. Many cameras incorporate narrow-angle spot meters to facilitate such measurements, because of the limited tonal range, an exposure compensation range of ±2 EV is often sufficient for using the Zone System with color film and digital sensors. Exposure value Exposure index Light meter Zone System Exposure bracketing Auto Exposure Bracketing
A color space is a specific organization of colors. In combination with physical device profiling, it allows for reproducible representations of color, for example, Adobe RGB and sRGB are two different absolute color spaces, both based on the RGB color model. When defining a color space, the reference standard is the CIELAB or CIEXYZ color spaces. For example, although several specific color spaces are based on the RGB color model, colors can be created in printing with color spaces based on the CMYK color model, using the subtractive primary colors of pigment. The resulting 3-D space provides a position for every possible color that can be created by combining those three pigments. Colors can be created on computer monitors with color spaces based on the RGB color model, a three-dimensional representation would assign each of the three colors to the X, Y, and Z axes. Note that colors generated on given monitor will be limited by the medium, such as the phosphor or filters. Another way of creating colors on a monitor is with an HSL or HSV color space, based on hue, with such a space, the variables are assigned to cylindrical coordinates.
Many color spaces can be represented as three-dimensional values in this manner, but some have more, or fewer dimensions, Color space conversion is the translation of the representation of a color from one basis to another. The RGB color model is implemented in different ways, depending on the capabilities of the system used, by far the most common general-used incarnation as of 2006 is the 24-bit implementation, with 8 bits, or 256 discrete levels of color per channel. Any color space based on such a 24-bit RGB model is limited to a range of 256×256×256 ≈16.7 million colors. Some implementations use 16 bits per component for 48 bits total and this is especially important when working with wide-gamut color spaces, or when a large number of digital filtering algorithms are used consecutively. The same principle applies for any color space based on the color model. CIE1931 XYZ color space was one of the first attempts to produce a space based on measurements of human color perception. The CIERGB color space is a companion of CIE XYZ.
Additional derivatives of CIE XYZ include the CIELUV, CIEUVW, RGB uses additive color mixing, because it describes what kind of light needs to be emitted to produce a given color. RGB stores individual values for red and blue, RGBA is RGB with an additional channel, alpha, to indicate transparency. Common color spaces based on the RGB model include sRGB, Adobe RGB, ProPhoto RGB, scRGB, one starts with a white substrate, and uses ink to subtract color from white to create an image
Wildlife of Bermuda
The flora and fauna of Bermuda form part of a unique ecosystem due to Bermudas isolation from the mainland of North America. The wide range of species and the islands form a distinct ecoregion. Located 900 km off the American East Coast, Bermuda is a chain of 184 islands. The islands are slightly hilly rather than having steep cliffs, with the highest point being 79m, the coast has many bays and inlets, with sandy beaches especially on the south coasts. Bermuda has a climate, warmed by the Gulf Stream current. Twenty of the islands are inhabited, and Bermuda is one of the most densely populated countries in the world, wildlife that could fly to the island or were carried there by winds and currents formed the species. There are no native mammals other than bats, and only two reptiles, but large numbers of birds and insects. Once on the island, organisms had to adapt to conditions, such as the humid climate, lack of fresh water, frequent storms. The area of the islands shrank as water rose at the end of the Pleistocene epoch.
Nearly 8,000 different species of flora and fauna are known from the islands of Bermuda, the number is likely to be considerably higher if all microorganisms, cave-dwellers and deep-sea species were counted. Today the variety of species on Bermuda has been increased by introductions. Many of these species have posed a threat to the native flora and fauna because of competition. Over 1000 species of plant are found on the islands. Of the 165 native species,17 are endemic, at the time of the first human settlement by shipwrecked English sailors in 1593, Bermuda was dominated by forests of Bermuda cedar with mangrove swamps on the coast. More deliberate settlement began after 1609, and colonists began clearing forests to use for building and shipmaking, by the 1830s, the demands of the shipbuilding industry had denuded the forests, but these recovered in many areas. In the 1940s the cedar forests were devastated by introduced scale insects, replanting using resistant trees has taken place since then, but the area covered by cedar is only 10% of what it used to be.
Another important component of the original forest was Bermuda palmetto, a palm tree. It now grows in a few patches, notably at Paget Marsh
A flash is a device used in photography producing a flash of artificial light at a color temperature of about 5500 K to help illuminate a scene. A major purpose of a flash is to illuminate a dark scene, other uses are capturing quickly moving objects or changing the quality of light. Flash refers either to the flash of light itself or to the flash unit discharging the light. Most current flash units are electronic, having evolved from single-use flashbulbs, modern cameras often activate flash units automatically. Flash units are built directly into a camera. Some cameras allow separate flash units to be mounted via an accessory mount bracket. In professional studio equipment, flashes may be large, standalone units, or studio strobes, studies of magnesium by Bunsen and Roscoe in 1859 showed that burning this metal produced a light with similar qualities to daylight. The potential application to photography inspired Edward Sonstadt to investigate methods of manufacturing magnesium so that it would burn reliably for this use and he applied for patents in 1862 and by 1864 had started the Manchester Magnesium Company with Edward Mellor.
It had the benefit of being a simpler and cheaper process than making round wire, mather was credited with the invention of a holder for the ribbon, which formed a lamp to burn it in. The packaging implies that the ribbon was not necessarily broken off before being ignited. An alternative to ribbon was flash powder, a mixture of powder and potassium chlorate, introduced by its German inventors Adolf Miethe. A measured amount was put into a pan or trough and ignited by hand, producing a brilliant flash of light, along with the smoke. This could be an activity, especially if the flash powder was damp. An electrically triggered flash lamp was invented by Joshua Lionel Cowen in 1899 and his patent describes a device for igniting photographers’ flash powder by using dry cell batteries to heat a wire fuse. Variations and alternatives were touted from time to time and a few found a measure of success in the marketplace, especially for amateur use. The use of powder in an open lamp was replaced by flashbulbs, magnesium filaments were contained in bulbs filled with oxygen gas.
Manufactured flashbulbs were first produced commercially in Germany in 1929, such a bulb could only be used once, and was too hot to handle immediately after use, but the confinement of what would otherwise have amounted to a small explosion was an important advance. A innovation was the coating of flashbulbs with a film to maintain bulb integrity in the event of the glass shattering during the flash
The Fabales are an order of flowering plants included in the rosid group of the eudicots in the Angiosperm Phylogeny Group II classification system. In the APG II circumscription, this includes the families Fabaceae or legumes, Polygalaceae or milkworts. Under the Cronquist system and some other plant classification systems, the order Fabales contains only the family Fabaceae, in the classification system of Dahlgren the Fabales were in the superorder Fabiflorae with three families corresponding to the subfamilies of Fabaceae in APG II. The Fabaceae, as the third-largest plant family in the world, contain most of the diversity of the Fabales, research in the order is largely focused on the Fabaceae, due in part to its great biological diversity, and to its importance as food plants. The Fabales are a order of plants, except only the subfamily Papilionoideae of the Fabaceae are well dispersed throughout the northern part of the North Temperate Zone
Suriana is a monotypic genus of flowering plants containing only Suriana maritima, which is commonly known as bay cedar. It has a distribution and can be found on coasts in the New. Bay cedar is a shrub or small tree, usually reaching a height of 1–2 m. The leaves are alternate, simple, 1–6 cm long and 0.6 cm wide, the grey-green, succulent foliage yields an aroma similar to that of cedar when crushed, hence the common name. Its yellow flowers are solitary or in short cymes among the leaves, flowers have a diameter of 1.5 cm when open, with petals 6–10 mm long and sepals 7–10 mm long. Bay cedar flowers throughout the year, after fertilisation, the flowers form clusters of five dry, hard drupes 3–4 mm in diameter. The drupes are buoyant and can maintain the viability of the seeds during long periods in seawater, allowing the seeds to be dispersed by the ocean
In photography, the term acutance describes a subjective perception of sharpness that is related to the edge contrast of an image. Acutance is related to the amplitude of the derivative of brightness with respect to space, due to the nature of the human visual system, an image with higher acutance appears sharper even though an increase in acutance does not increase real resolution. Historically, acutance was enhanced chemically during development of a negative, in the example image, two light gray lines were drawn on a gray background. As the transition is instantaneous, the line is as sharp as can be represented at this resolution, acutance in the left line was artificially increased by adding a one-pixel-wide darker border on the outside of the line and a one-pixel-wide brighter border on the inside of the line. The actual sharpness of the image is unchanged, but the apparent sharpness is increased because of the greater acutance. In this somewhat overdone example most viewers will be able to see the borders separately from the line, several image processing techniques, such as unsharp masking, can increase the acutance in real images.
Low-pass filtering and resampling often cause overshoot, which increases acutance, but can reduce absolute gradient and resampling can cause clipping and ringing artifacts. An example is bicubic interpolation, widely used in processing for resizing images. Thus the acutance of an image is a vector field, coarse grain or noise can, like sharpening filters, increase acutance, hence increasing the perception of sharpness, even though they degrade the signal-to-noise ratio
In photography, the metering mode refers to the way in which a camera determines the exposure. Cameras generally allow the user to select between spot, center-weighted average, or multi-zone metering modes, various metering modes are provided to allow the user to select the most appropriate one for use in a variety of lighting conditions. With spot metering, the camera will only measure a small area of the scene. This will by default be the centre of the scene. The user can select a different off-centre spot, or to recompose by moving the camera after metering. The first spot meter was built by Arthur James Dalladay, editor of The British Journal of Photography in about 1935, a few models support a Multi-Spot mode which allows multiple spot meter readings to be taken of a scene that are averaged. Some cameras, the OM-4 and T90 included, support metering of highlight, spot metering is very accurate and is not influenced by other areas in the frame. It is commonly used to very high contrast scenes.
The area around the back and hairline will become over-exposed, spot metering is a method upon which the Zone System depends. In many cases the camera will over or underexpose, when using the spot mode, modern cameras tend to find the correct exposure precisely. In complex light situations though, professional photographers tend to switch to manual mode, another example of spot metering usage would be when photographing the moon. Due to the dark nature of the scene, other metering methods tend to overexpose the moon. Spot metering will allow for more detail to be out in the moon while underexposing the rest of the scene. More commonly, spot metering is used in photography, where the brightly lit actors stand before a dark or even black curtain or scrim. Spot metering only considers the actors in this case, while ignoring the overall darkness of the scene, in this system, the meter concentrates between 60 to 80 percent of the sensitivity towards the central part of the viewfinder. The balance is feathered out towards the edges, some cameras will allow the user to adjust the weight/balance of the central portion to the peripheral one.
When moving the point off center the camera will proceed as above. Although promoted as a feature, center-weighted metering was originally a consequence of the meter cell reading from the screen of SLR cameras
Colorfulness or saturation in colorimetry and color theory refers to the perceived intensity of a specific color. Colorfulness is the visual sensation according to which the color of an area appears to be more or less chromatic. Chroma is the relative to the brightness of a similarly illuminated area that appears to be white or highly transmitting. Therefore, chroma should not be confused with colorfulness, saturation is the colorfulness of a color relative to its own brightness. A highly colorful stimulus is vivid and intense, while a less colorful stimulus appears more muted, with no colorfulness at all, a color is a “neutral” gray. Any color can be described using three color appearance parameters — colorfulness and hue, saturation is one of three coordinates in the HSL and HSV color spaces. The saturation of a color is determined by a combination of light intensity, the purest color is achieved by using just one wavelength at a high intensity, such as in laser light. If the intensity drops, as a result the saturation drops, to desaturate a color of given intensity in a subtractive system, one can add white, gray, or the hues complement.
CIELUV The chroma normalized by the lightness, s u v = C u v ∗ L ∗ =132 +2 where is the chromaticity of the white point, and chroma is defined below. Nevertheless, this provides a reasonable predictor of saturation. S a b = C a b ∗ C a b ∗2 + L ∗2100 % where Sab is the saturation, L* the lightness and C*ab is the chroma of the color. CIECAM02 The square root of the colorfulness divided by the brightness, M is proportional to the chroma C, thus the CIECAM02 definition bears some similarity to the CIELUV definition. An important difference is that the CIECAM02 model accounts for the conditions through the parameter FL. Different color spaces, such as CIELAB or CIELUV may be used, the naïve definition of saturation does not specify its response function. However, both color spaces are nonlinear in terms of perceived color differences. It is possible—and sometimes desirable—to define a quantity that is linearized in term of the psychovisual perception. The transformation of to is given by, C a b ∗ = a ∗2 + b ∗2 h a b = arctan b ∗ a ∗ and analogously for CIE L*C*h.
The chroma in the CIE L*C*h and CIE L*C*h coordinates has the advantage of being more psychovisually linear, and therefore, chroma in CIE1976 L*a*b* and L*u*v* color spaces is very much different from the traditional sense of saturation
The amount of light that reaches the film or image sensor is proportional to the exposure time. 1/500th of a second will let half as much light in as 1/250th, the cameras shutter speed, the lenss aperture, and the scenes luminance together determine the amount of light that reaches the film or sensor. Exposure value is a quantity that accounts for the shutter speed and this will achieve a good exposure when all the details of the scene are legible on the photograph. Too much light let into the results in an overly pale image while too little light will result in an overly dark image. Multiple combinations of speed and f-number can give the same exposure value. According to exposure value formula, doubling the exposure time doubles the amount of light, for example, f/8 lets 4 times more light into the camera as f/16 does. In addition to its effect on exposure, the speed changes the way movement appears in photographs. Very short shutter speeds can be used to freeze fast-moving subjects, very long shutter speeds are used to intentionally blur a moving subject for effect.
Short exposure times are called fast, and long exposure times slow. Adjustments to the aperture need to be compensated by changes of the speed to keep the same exposure. The agreed standards for shutter speeds are, With this scale, camera shutters often include one or two other settings for making very long exposures, B keeps the shutter open as long as the shutter release is held. T keeps the open until the shutter release is pressed again. The ability of the photographer to take images without noticeable blurring by camera movement is an important parameter in the choice of the slowest possible speed for a handheld camera. Through practice and special techniques such as bracing the camera, arms, or body to minimize movement, using a monopod or a tripod. If a shutter speed is too slow for hand holding, a support, usually a tripod. Image stabilization on digital cameras or lenses can often permit the use of shutter speeds 3–4 stops slower, Shutter priority refers to a shooting mode used in cameras.
It allows the photographer to choose a shutter speed setting and allow the camera to decide the correct aperture and this is sometimes referred to as Shutter Speed Priority Auto Exposure, or TV mode, S mode on Nikons and most other brands. Shutter speed is one of methods used to control the amount of light recorded by the cameras digital sensor or film