Photography  my small typic 

is the science, art, application and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film.

Typically, a lens is used to focus the light reflected or emitted from objects into a real image on the light-sensitive surface inside a camera during a timed exposure. With an electronic image sensor, this produces an electrical charge at each pixel, which is electronically processed and stored in a digital image file for subsequent display or processing. The result with photographic emulsion is an invisible latent image, which is later chemically "developed" into a visible image, either negative or positive depending on the purpose of the photographic material and the method of processing. A negative image on film is traditionally used to photographically create a positive image on a paper base, known as a print, either

my photographic in tripura

 by using an enlarger or by contact printing.

Photography is employed in many fields of science, manufacturing (e.g., photolithography), and business, as well as its more direct uses for art, film and video production, recreational purposes, hobby, and mass communication.

The depth of field is the region where the size of the circle of confusion is less than the resolution of the human eye.

Though difficult to quantify, some lenses have subjectively more pleasing out-of-focus areas. "Good" bokeh is especially important for macro lenses and long telephoto lenses, because they are typically used in situations that produce shallow depth of field. Good bokeh is also important for medium telephoto lenses (typically 85–150 mm on 35 mm format). When used in portrait photography (for their "natural" perspective), the photographer usually wants a shallow depth of field, so that the subject stands out sharply against a blurred background.

editing by photoshop monu pansotra

Bokeh characteristics may be quantified by examining the image's circle of confusion. In out-of-focus areas, each point of light becomes an image of the aperture, generally a more or less round disc. Depending on how a lens is corrected for spherical aberration, the disc may be uniformly illuminated, brighter near the edge, or brighter near the center. A well-known lens that exhibited the latter "soap-bubble" characteristic was that produced by Hugo Meyer & Co., more recently revived by Meyer Optik Görlitz.^[10]

Lenses that are poorly corrected for spherical aberration will show one kind of disc for out-of-focus points in front of the plane of focus, and a different kind for points behind.^[11] This may actually be desirable, as blur circles that are dimmer near the edges produce less-defined shapes which blend smoothly with the surrounding image. The shape of the aperture has an influence on the subjective quality of bokeh as well. For conventional lens designs (with bladed apertures), when a lens is stopped down smaller than its maximum aperture size (minimum f-number), out-of-focus points are blurred into the polygonal 

Nikon camera D7200

shape formed by the aperture blades. This is most apparent when a lens produces hard-edged bokeh. For this reason, some lenses have many aperture blades and/or blades with curved edges to make the aperture more closely approximate a circle rather than a polygon. Minolta has been on the forefront of promoting and introducing lenses with near-ideal circular apertures since 1987, but most other manufacturers now offer lenses with shape-optimized diaphragms, at least for the domain of portraiture photography. In contrast, a catadioptric telephoto lens renders bokehs resembling doughnuts, because its secondary mirror blocks the central part of the aperture opening. Recently, photographers have exploited the shape of the bokeh by creating a simple mask out of card with shapes such as hearts or stars, that the photographer wishes the bokeh to be, and placing it over the lens.^[12]

Lenses with 11, 12, or 15 blade iris diaphragms are often claimed to excel in bokeh quality. Because of this, the lenses do not need to reach wide apertures to get better circles (instead of polygons). In the past, wide aperture lenses (f/2, f/2.8) were very expensive, due to the complex mathematical design and manufacturing know-how required, at a time when all computations and glass making were done by hand. Leica could reach a good bokeh at f/4.5. Today it is much easier to make an f/1.8 lens, and a 9-bladed lens at f/1.8 is enough for an 85mm lens to achieve great bokeh.

Some lens manufacturers including Nikon,^[13] Minolta, and Sony make lenses designed with specific controls to change the rendering of the out-of-focus areas.

The Nikon 105 mm DC-Nikkor^[14] and 135 mm DC-Nikkor^[15] lenses (DC stands for "Defocus Control") have a control ring that permits the overcorrection or undercorrection of spherical aberration to change the bokeh in front of and behind the focal plane.

The Minolta/Sony STF 135mm f/2.8 [T4.5] (with STF standing for smooth trans focus) is a lens specifically designed to produce pleasing bokeh. It is possible to choose between two diaphragms: one with 9 and another with 10 blades. An apodization filter is used to soften the aperture edges which results in a smooth defocused area with gradually fading circles. Those qualities made it the only lens of this kind on the market from its introduction in 1999 to 2014. In 2014 Fujifilm announced a lens utilizing a similar apodization filter in the Fujinon XF 56mm F1.2 R APD lens.^[16] Sony added the Sony FE 100mm F2.8 STF GM OSS in 2017.^[17]

The 'Sigma YS System Focusing' 135mm f/2.8 also has an extra manually-moved component, intended to compensate for aberration at close-focus distances. It can be re-purposed for defocus control. ^[18]

In 2015, Meyer Optik USA Inc. launched a Kickstarter campaign to produce the Trioplan f2.9/50, a new lens based on one originally produced by Hugo Meyer & Co.; both lenses exhibit a characteristic "soap-bubble" bokeh.^[19]

The use of anamorphic lenses will cause bokeh to appear differently along the horizontal and vertical axes of the lens, becoming ellipsoidal compared to those in a spherical lens.

In 2016, Apple Inc. released the iPhone 7 Plus which can take pictures with "Portrait Mode" (a bokeh like effect).^[20]Samsung's Galaxy Note 8 has a similar effect available. Both of these phones use dual cameras to detect edges and create a "depth map" of the image, which the phone uses to blur the out-of-focus portions of the photo. Other phones, like the Google Pixel, only use a single camera and machine learning to create the depth map.^[21]

In 2017, Vivo released a smartphone with dual front lenses for selfies with bokeh. The first, a 20 MP lens, uses a 1/2.78" sensor with f/2.0 aperture, while the second, an 8 MP f/2.0 lens, captures depth information. Bokeh can be made with a combination of both lenses, and shots can be refocused even after they are captured, adding bokeh effects with different depths.^[22]

thanks every one 

In early 2018, the Honor 9 Lite smartphone was released with quad cameras (two dual-lens). Both the front and back cameras have a 13MP main lens and a 2MP lens for capturing bokeh depth information.^[23]