In photography, bokeh ( "English respelling pronunciation"> BOH -kay - is also sometimes pronounced as < span> "English respelling pronunciation"> BOH -k? , Japanese: Ã, Bokeh are often most visible around small background beams, such as specular reflections and light sources, which is why it is often associated with the area. However, bokeh is not limited to the spotlight; blur occurs in all areas outside the focus of the image. Video Bokeh
Origin
This term is derived from the Japanese word boke ( ?? or ?? ), meaning "blur" or "haze", or boke-aji ( < span lang = "ja" title = "Japanese text"> ??? ), "blurred quality". The Japanese term boke is also used in the sense of mental fog or senility. The term bokashi ( ??? ), which means blurring or deliberate gradation.
The English spelling bokeh was popularized in 1997 in Photo Techniques magazine, when Mike Johnston, the editor at the time, commissioned three papers on the topic for the March/April 1997 issue; he changed the spelling to suggest correct pronunciation to English speakers, saying "it is properly pronounced with bo as in bone and into like in Kenneth, with the same emphasis on both syllables". The spelling of bokeh and bale has been used since at least 1996, when Merklinger suggests "or Bokeh if you prefer." The term bokeh has appeared in photography books since 1998. Sometimes pronounced (boke-uh).
Maps Bokeh
Bokeh and lens design
Although it is difficult to measure, some lenses have a more pleasant outside focus area. "Excellent" bokeh are very important for macro lenses and long telephoto lenses, as they are usually used in situations that produce shallow depth of field. Good bokeh is also important for medium telephoto lenses (typically 85-150 mm in 35 mm format). When used in portrait photography (for their "natural" perspective), photographers usually want shallow depth of field, so the subject stands out sharply against a blurred background.
The characteristics of Bokeh can be quantified by examining the image confusion circle. Outside the focus area, each light point becomes the image of the aperture, generally more or less disc rotation. Depending on how the lens is corrected for spherical aberrations, the disk can be disguised evenly, brighter near the edges, or brighter near the center. Famous lenses that show the characteristics of the last "bubbles" are those produced by Hugo Meyer & amp; Co., recently revived by Meyer Optik GÃÆ'¶rlitz.
Lenses that are not corrected properly for spherical aberrations will show one type of disk for the focal points in front of the focal plane, and different types for the dot behind. This may actually be desirable, because the dim circles dimmers near the edges produce undefined shapes that blend smoothly with the surrounding image. The shape of the openings has an influence on the subjective quality of the bokeh as well. For conventional lens design (with a bladed hole), when the lens stops smaller than the maximum aperture size (f-number minimum), the points outside the focus become blurred into the polygonal shape formed by the aperture blades. This is most evident when a lens produces a sharp-eyed bokeh. For this reason, some lenses have many aperture and/or slats with curved edges to make the aperture closer to the circle than the polygon. Minolta has been at the forefront of promoting and introducing lenses with almost ideal circular holes since 1987, but most other manufacturers now offer lenses with a form-optimized diaphragm, at least for portrait photography domains. In contrast, the catadioptric telephoto lens makes a donut-like bokeh, since its secondary mirror blocks the center of the aperture opening. Recently, the photographer has exploited the bokeh form by creating a simple mask of the card with a heart-like shape or star, which the bokeh photographer wants, and placing it over the lens.
Lenses with 11, 12, or 15 blade diaphragms are often claimed to be superior in bokeh quality. Therefore, the lens does not need to reach the wide aperture to get a better circle (not a polygon). In the past, wide-open (f/2, f/2.8) openings were very expensive, due to the complex mathematical design and manufacturing knowledge required, at a time when all calculations and glass making were done by hand. Leica can achieve a good bokeh in f/4.5. Today it's much easier to make the f/1.8 lens, and the 9-bladed lens in f/1.8 is enough for the 85mm lens to achieve the big bokeh.
Several lens manufacturers including Nikon, Minolta, and Sony make lenses designed with special controls to change rendering areas beyond focus.
The Nikon 105 mm DC-Nikkor and 135 mm DC-Nikkor lenses (DC stands for "Defocus Control") have a control ring that allows overcorrection or undercorrection of aberration ball to change the bokeh in front and behind the focal plane.
The Minolta/Sony STF 135mm f/2.8 [T4.5] (with STF stand for smooth trans focus) is a specially designed lens to produce a fun bokeh. It is possible to choose between two diaphragms: one with 9 and another with 10 blades. The apodization filter is used to smooth the end of the aperture resulting in a smooth defocused area with a gradually fading loop. The quality makes it the only lens of this type on the market since it was introduced in 1999 to 2014. In 2014, Fujifilm announces a lens that uses a similar apodization filter in the Fujinon XF 56mm F1.2 R APD lens. Sony added Sony FE 100mm F2.8 STF GM OSS in 2017.
The 135m f/2.8 'Sigma YS System Focusing' also has extra components moved manually, which are intended to compensate for irregularities at close-range focal distances. This can be redesigned for defocus control.
In 2015, Meyer Optics USA Inc. launched the Kickstarter campaign to produce Trioplan f2.9/50, a new lens based on that originally manufactured by Hugo Meyer & Together.; both lenses show the typical "bubble-bubble" bokeh.
The use of anamorphic lenses will cause bokeh to appear differently along the horizontal and vertical axis of the lens, becoming ellipsoidal compared to round lenses.
In 2016, Apple Inc. released the iPhone 7 Plus which can take pictures with "Portrait Mode" (effects like bokeh). Samsung Galaxy Note 8 has similar effects available. Both phones use dual cameras to detect edges and create "depth maps" of images, which mobile phones use to blur unfocused photos. Other phones, such as Google Pixel, use only one camera and machine learning to create depth maps.
In 2017, Vivo released a smartphone with dual front lens for selfie with bokeh. The first, the 20 MP lens, uses a 1/2.78 "sensor with f/2.0 aperture, while the second, 8 MP f/2.0 lens captures the depth information.Bokeh can be made with a combination of both lenses, and the shot can refocus even after they are captured, add bokeh effects with different depths.
In early 2018, the Honor 9 Lite smartphone was released with a quad camera (two dual lenses). Both front and rear cameras have 13MP main lens and 2MP lenses to capture bokeh depth information.
Emulation
Bokeh can be simulated by combining images with a kernel that matches an unfocused point source image taken with a real camera. Unlike conventional convolution, this convolution has a kernel that depends on the distance of each point of the image and - at least in principle - must include image points clogged by objects in the foreground. Also, bokeh is not just any blur. For the first approach, defocus blur is a convolution by a uniform disk, a more computationally intensive operation than the "standard" Gaussian blur; the first produces a sharp circle around the spotlight while the second is a much softer effect. Diffraction can change the effective form of blur. Some graphics editors have filters to do this, usually called "Lens Blur."
Alternative mechanical mechanisms have been proposed to produce bokeh in small aperture cameras such as compacts or camera phones, called image destabilization, in which both lens and sensor are moved to maintain focus on one focal plane, while focusing on the nearest one. This effect currently produces blur in just one axis.
Some sophisticated digital cameras have a bokeh feature that takes several pictures with different holes and focuses and then organizes them manually afterwards into a single image. The more sophisticated system of bokeh uses a hardware system of 2 sensors, one sensor for taking photos as usual while another recording depth information. The Bokeh effect and refocusing can then be applied to the image after the photo is taken.
Other apps
In 2009, a research group at MIT Media Lab showed that the bokeh effect can be used to create small barcodes, or bokodes. Using a barcode as small as 3 mm with a small lens on top, if the barcode is viewed unfocused through a regular camera that is focused on the infinite, the resulting image is large enough to scan the information in the barcode.
See also
- Deviation in optical systems
- Airy disk
- Anamorphic format
- Circle of confusion
- Light field camera
- Effect mandelbaum
- Orb (optical)
- Gentle focus
- Special effects
References
Bokeh Calculator Tools
- JS Open Source Code for Bokeh Calculator
- Tool makes it possible to compare the background blur of different lenses and cameras
Source of the article : Wikipedia
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