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[Concept]
The fisheye lens is a focal length of 16mm or shorter focal length lens and perspective close to or equal to 180 ° lens.
It is an extreme wide-angle lens and fisheye is it commonly known.
Lens for maximum photographic perspective, this photographic lens before the lens diameter and was parabolic-like protruding eyes with the fish is quite similar to the front of the lens, "fisheye," hence the name.
Fisheye ultra wide angle lens in a special kind of lens, perspective and strive to meet or exceed the scope of the human eye can see. Therefore, the fish-eye lens and the people in the eyes of real-world scene there is a big difference, because the scenery we see in real life is a fixed form of rules, the picture through the fisheye effect is beyond the scope of .
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The original rationale
The shorter the focal length, the greater the angle, the more intense deformation due to the optical principle.
In order to achieve a large view of 180 degrees, the fish-eye lens designers have to make sacrifices, which allows reasonable presence of this distortion (barrel distortion).
The result is to remain unchanged, the other should be horizontal or vertical scene have taken place in the corresponding changes in addition to the scene at the center of the screen.
It is this strong visual effect for those who are imaginative and courage to challenge photographers to provide the opportunity to showcase the creativity of the individual.
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[For use]
Biggest role is the perspective of a large range of general perspective can reach 220 ° or 230 ° for close-up shots of a wide range of scenery;
In approaching the subject when shooting can cause a very strong perspective effect, emphasizing the subject near the far smaller compared to the camera screen with a stirring appeal;
Has quite a long depth of field, and is conducive to the long depth of field effect performance photos.
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[Sub class]
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(1) diagonal fisheye lens
Rectangle to produce a full frame of the film deformation images.
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(2) imagery is round
Taken on the film to produce a circular image of the frame width of the film diameter.
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Either imaging camera with a fisheye lens, distortion is quite severe, and a strong sense of perspective convergence. It is often used as a special effects lens, a stretched the fisheye arm, will become twice as long than the original.
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[Features]
A large angle, a very wide range of subject.
Sense of perspective greatly exaggerated.
3 fisheye there is a serious distortion, but you can get dramatic results.
Expensive, originally designed for astronomical photography.
5 The first lenses protrude, you can not use the usual filter and replace it with "built-in filters.
6. Larger
Fisheye lens for 35 mm single-lens reflex camera, for example, when this fish-eye lens is installed in the smaller 35 mm single-lens reflex camera body, a "head (lens) body (machine body) "feeling, and the weight of the fish-eye lens is not light (such as the Nikkor 6 mm / F2.8 manual focus fisheye lens weighs 5200 g), single-lens reflex camera fitted with a fisheye lens, camera and the overall weight of the lens increases, the forward center of gravity, the photographer held steady camera grip the camera when shooting.
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[Use]
A. Interesting prospects can generate a strong visual impact;
Two. The depth of field can range from a few centimeters to infinity;
3. Select as few lines as possible, the surface as the subject; composition to make your subject placed in the center of the screen, doing so allows distortion minimum;
4. On the contrary, select the possible number of horizontal lines and is easy to identify the scene at the edge of the screen, distortion effect can;
5 Observe the edge of the viewfinder when framing to see if the photographer's hands and feet, with the camera or the photographer himself to be eaten in the lens, so as not to affect the artistic effect of the screen;
6. For most of the fish-eye lens, the commonly used filter can not use.
7. For the production of panoramic images, based on realistic scenarios widely used in entertainment, real estate, museums, schools and other agencies of publicity and demonstration projects. Can be found in the Google Maps Street View feature.
Eight. The front lens of the fisheye lens diameter and thrown to the front of the lens, so the lens can not be installed like a normal lens as the filter.
The fisheye lens is usually built-in filter, according to the shooting needs to manipulation by the photographer filter conversion ring on the lens, so need to convert the filter to the lens of the photographic optical path.
9 fisheye lens before the lens is very important in the whole lens lens, it is thrown to the front of the lens, the photographer shooting operation (especially nearer the subject shooting), paying particular attention to not hit the lens.
10. Some old-fashioned fish-eye lens with 35 mm single-lens reflex cameras connected, the rear of the lens into the camera body darker, the camera's reflex mirror must reveal the lock, the camera's pentaprism viewfinder will not be able to use the required in camera set on additional framing to carry out the photography.
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[Select]
One want to use a fisheye lens, the photographer, the first and most critical step is to decide what you want to get the kind of fish-eye lens effect, there are three sizes to choose from:
Fisheye / Fisheye mirror / a homemade device.
Only 35mm SLR camera has a true fisheye lens. Focal length around 8mm. The image was completely round, a viewing angle of 180 degrees; a few paragraphs up to 220 degrees, mainly used in science and technology photography.
(3) fish-eye lens is composed of many optical lenses, the need for precision molding and assembly, so the price is very expensive.
Contrast, is much cheaper to buy a fish eye lens attached.
This additional mirror focal length, but can change the original focus of the lens, such as 0.4 times the additional mirror mounted on a standard 50mm lens, the focal length becomes: 50 × 0.42mm, if installed in the 28mm wide-angle lens, the focal length of change can be imagined.
Only the fisheye lens to produce special effects will appear in your viewfinder.
5 may wish to try a home-made fish-eye device:
Take a round hole in the spare lens cover, a home "Cat" fixed mirror which, then this lens cap in a standard head, you can produce the effect of the fisheye lens, this method is inexpensive and allows I enjoy the hands of some little fun.
15mm and 16mm fisheye is more common for 35mm SLR cameras.
24mm, 30mm, 35mm fish-eye lens for Mamiya 645 (6 × 4.5cm), Hasselblad (6 x 6cm), the Pentax 67 (6 × 7cm) medium format SLR cameras.
Obviously, the fish-eye lens is not commonly used lens. When the basic lens has been complete, but also try to play it.
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[Fisheye ultra wide-angle lens]
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1 [focal length]
Some people think that the fish-eye lens focal length must be smaller than the ultra-wide-angle lens, but does not necessarily
Such as the Nikon 13 mm and 15 mm ultra wide angle lens, but only 16 mm fisheye lens.
135 fisheye lens camera focal length is --- 17 mm ultra-wide-angle lens focal length is 13 --- 24 mm
Frame of 60x60 mm 120 camera, fisheye lens focal length is 24 mm ultra wide-angle lens focal length is 35 mm.
Frame of 60x70 mm 120 camera, fisheye lens focal length is 37 mm ultra wide-angle lens focal length is 50 mm.
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(2) the size of the perspective / correct image distortion]
Such as ultra-wide-angle lens of 13 mm, field of view angle of only 118, while the 17 mm fisheye lens. FOV has reached 180.
The ultra-wide-angle and the other lens, trying to correct the distortion of the edge of the screen, and strive to shoot the picture is consistent with the physical.
Fisheye intentionally retained the barrel distortion of the image for the exaggeration of the deformation effect, shoot the picture in addition to the central part of other straight into a curved arc.
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【Article is excerpted from: Baidu Encyclopedia】
【Network reprint / Just reference】
【Translation is by Goolge】
