Is the fish-eye lens a concave lens or a concave lens?
Fish-eye lenses were usually composed of a front group of imaging lenses and a rear group of correction lenses. The front group of imaging lenses was generally a concave lens for imaging, but the entire fish-eye lens was a complex optical system. It was not only composed of simple concave lenses or concave lenses, but also through the combination of multiple lenses to correct aberrations, aberrations, and other problems to achieve its special imaging effect, such as the angle of view being close to or equal to 180°. Read more exciting novels for free
How to know the focal length of a concave lens
The focal length of the concave lens can be determined by: 1. ** Concave lens assisted secondary imaging method **: Place a light source on the main optical axis of the concave lens, adjust the distance between the light source and the concave lens, so that the object point becomes a real image; According to the principle of virtual object imaging (an object becomes a real image through a lens, and the emitted light is refracted by the second lens before reaching the image point, then the first image can be regarded as a virtual object in the second image, and the focal length of the virtual object is negative), the focal length of the concave lens is obtained. 2. ** Plane mirror auxiliary method **: Put the point light source behind the concave lens to form an image, put a flat mirror vertical to the main optical axis behind the image, and put a small screen next to the light source; then put the concave lens between the concave lens and the image, move the concave lens back and forth, so that the light is refracted by the concave lens and shot out parallel. At this time, it forms a real image on the screen, and then calculate the focal length. 3. ** focal length stacking method **: measure the equivalent focal length of the two lenses and the focal length of the concave lens, and calculate the focal length of the concave lens through a formula (this method is suitable for thinner lenses, and the absolute value of the focal length of the concave lens is greater than the focal length of the concave lens. The formula derivation uses the knowledge of virtual object imaging). 4. ** Similar triangle method **: The sunlight (parallel light) is shot along the main axis to the concave lens. The diameter of the concave lens, the diameter of the light spot on the screen behind the concave lens, and the distance from the concave lens to the screen are measured. According to the geometric relationship, the focal length of the concave lens is calculated by using the similarity ratio. 5. **"Incident-exit" ray method **: insert two needles parallel to the main optical axis on one side of the concave lens, and also insert two needles on the other side of the concave lens, so that the images of these two needles and the first two needles are in a straight line, and then calculate the focal length by making the incident ray and the exit ray. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to know the focal length of a concave lens
以下几种方法可用于确定凸透镜焦距的大小： **一、利用平行光聚焦法** 1. **原理** - 让平行光（如太阳光）平行于主光轴射入凸透镜，光在透镜的两面经过两次折射后，会集中在轴上的一点，这个点就是凸透镜的焦点。焦点到凸透镜光心的距离就是焦距。 2. **操作** - 将凸透镜正对着太阳光，在凸透镜的另一侧放一张白纸，调整白纸与凸透镜之间的距离，直到白纸上出现一个最小、最亮的光斑，这个光斑所在的位置就是焦点的位置。然后用刻度尺测量出光斑到凸透镜光心的距离，这个距离就是焦距。 **二、根据成像规律公式计算** 1. **成像规律公式** - 根据凸透镜成像规律，物距\(u\)、像距\(v\)和焦距\(f\)满足公式\(\frac{1}{u}+\frac{1}{v}=\frac{1}{f}\)。 2. **操作步骤** - 首先确定物距和像距。将物体放在凸透镜前，通过移动光屏（用于承接像）找到清晰的像，测量出物体到凸透镜光心的距离\(u\)（物距）以及像到凸透镜光心的距离\(v\)（像距）。然后将\(u\)和\(v\)的值代入公式\(\frac{1}{u}+\frac{1}{v}=\frac{1}{f}\)，计算出焦距\(f\)。 **三、利用已知焦距的凸透镜组合计算（当有两个凸透镜时）** 1. **公式推导** - 假设凸透镜(1)的焦距为\(f_1\)，凸透镜(2)的焦距为\(f_2\)，两者靠得很近，两个凸透镜的中心距离为\(d\)，以凸透镜(1)的透镜中心用为合并以后的透镜的中心。有一束平行光射入透镜(1)，在焦点处形成了一个亮点，放上凸透镜(2)后，以此亮点作为凸透镜(2)的物，那么这个物离开透镜(2)的距离为\(u_2 =-(f_1 - d)\)。根据凸透镜成像规律公式\(\frac{1}{u_2}+\frac{1}{v_2}=\frac{1}{f_2}\)计算此时凸透镜(2)所成的像的位置\(v_2=\frac{1}{\frac{1}{f_2}+\frac{1}{(f_1 - d)}}\)，再计算由凸透镜(2)形成的像离开凸透镜(1)的距离为\(v_2 + d\)，这个距离就是凸透镜组合的焦距\(f=\frac{1}{\frac{1}{f_2}+\frac{1}{(f_1 - d)}}+d\)。 2. **操作要点** - 确定两个凸透镜的焦距\(f_1\)和\(f_2\)以及它们之间的距离\(d\)，按照上述公式计算组合后的焦距。这种方法适用于有两个凸透镜且它们之间距离较近的情况。 **四、根据凸透镜的厚度判断（定性判断）** 1. **原理** - 凸透镜的厚度越大，焦距越小。这是因为凸透镜对光的会聚作用与厚度有关，厚度越大，对光的会聚能力越强，从而焦距越小。 2. **实际应用** - 在没有精确测量工具的情况下，可以通过比较不同凸透镜的厚度来大致判断它们焦距的相对大小。例如，在多个凸透镜中，较厚的凸透镜可能具有较小的焦距。 <a href="/?from=ask_words" style="color:red" target="_blank">点击前往免费阅读更多精彩小说</a>
Fish-eye lens is
A fisheye lens was a lens with a focal length of about 6 - 16mm and a viewing angle close to or equal to 180°. It was a type of ultra-wide-angle lens. Its front lens was shaped like a parabola and protruded to the front of the lens, which was similar to the eyes of a fish, hence its name. The concept was proposed and developed in 1906. In the 1920s, it was used for the study of cloud formation in meteorology. Robin Hill was the first person to truly create a fisheye lens and use it for commercial use. Mass production began in the 1960s. It was usually composed of a front group of imaging lenses and a rear group of correction lenses. It was divided into half-frame fisheye lenses and full-frame fisheye lenses. It was first used in photography to create artistic photos with a large field of view and large distortion. It was also widely used in fields that required wide-angle imaging, such as surveillance, dome imaging, aerospace cameras, and other industrial, medical, and scientific research fields. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Is the mirror at the corner of the road a flat mirror? Why is it a concave lens?
The mirror at the corner of the road was not a concave lens. It was usually a concave mirror (not a flat mirror). Convex mirrors have the following characteristics that make them suitable for use at road corners: 1. [Expands field of vision: Convex mirror can reflect a larger range of scenes.] At the corner of the road, the driver could see a large range of traffic conditions on the other side of the curve through the concave mirror, such as cars and pedestrians, which helped to react in advance and ensure traffic safety. 2. [Image characteristics: Convex mirror image is a vertical, reduced virtual image.] Although this kind of imaging feature made the object seen smaller than the actual one, it could display a wider field of view under the limited mirror area. It was very effective for traffic monitoring and safety tips at the corner of the road. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
computer fish-eye lens
A fisheye lens was a lens with a focal length of about 6 - 16mm and a viewing angle close to or equal to 180°. It was a type of ultra-wide-angle lens. Its front lens protruded toward the front of the lens in a parabola shape, similar to a fisheye. If a computer wanted to use a fisheye lens, it might be used for external cameras and other devices to achieve special shooting effects, such as creating artistic images with large field of view and large distortion. It could be used for creative photography, surveillance, or specific industrial, medical, scientific research, and other fields that required wide-angle imaging. Fisheye lenses were first used in photography. They were developed in 1906 and used to study the formation of clouds in the 1920s. They were mass-produced in the 1960s. They were divided into half-frame fisheye lenses and full-frame fisheye lenses. They were usually composed of a front group of imaging lenses and a rear group of correction lenses. At present, there were also a variety of fisheye lens products that were suitable for different camera mounts. While ensuring the image quality and other functions, they were also developing in the direction of light and portable. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Fish-eye lens for the seascape
The fisheye lens could be used to capture seascapes and had a unique imaging effect. For example, the AF-S fisheye Nikkor 8 - 15mm f/3.5 - 4.5E ED lens used three pieces of low-dispersion (ED) glass lenses to effectively reduce the horizontal color difference that caused the color halo. It could also achieve high sharpness and contrast at the edge of the image, which could provide good image quality for landscape photography (including seascape). The filter slot was located at the opening of the lens mount, which could be inserted after cutting the third-party filter insert on the market. It provides filter support for seascape shots. There was also a fish-eye lens suitable for shooting seascapes. Its maximum aperture was only f/8, and the viewing angle reached 162°. It used four sets of four optical structures, and the lens was coated with seven layers of RMC to effectively reduce ghostly shadows and glare. When using the fisheye lens to shoot the seascape, you can use its unique perspective. The closer the line to the edge, the more exaggerated the distortion. If you arrange some of the seascape elements that you want to highlight at the edge of the picture, you can exaggerate its distortion, thus forming a special picture effect. If you arrange the main body in the center of the picture, it will be more horizontal. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Fish-eye lens and super wide-angle lens are recommended
The following are some recommendations for fisheye lenses and ultra-wide-angle lenses, but please note that the choice of lens depends on personal shooting needs, camera model, budget, and other factors. ** 1. Fisheye lens ** 1. ** Nikon's "God's Eye" 6mm ** - This was a full-circle fisheye lens with a 180-degree angle of view in both vertical and horizontal directions. It could include all the images in front of the lens. However, this type of product was a special-purpose lens. The shooting subject was relatively narrow, and it was impossible to simply correct the distortion to output a conventional ultra-wide-angle image. 2. ** Canon/Nikon 8 - 15mm (wide-angle)** - It was a full-circle fisheye lens with the unique imaging effect of a fisheye lens. It was suitable for specific artistic creations or special shooting needs. 3. ** 1,000 yuan domestic fish-eye lens (mostly in the half-circle fish-eye category)** - For those who had limited budget and just wanted to experience the fisheye effect, or for some non-professional shooting scenes that did not require high quality (such as amateur creative shooting), it could be considered. However, when it was corrected to an ordinary super wide-angle lens later, the edge quality would be seriously lost. ** 2. Ultra-wide angle lens ** 1. ** SonyFE35mmf/1.4GM (Fixed Focus)** - This was a super wide-angle lens with a Sony E-mount. It cost 11300 yuan and had good optical performance. 2. ** Canon RF14 - 35mm f/4L IS USM (zoom)** - Canon's ultra-wide-angle zoom lens with an RF-mount was priced at 13999 yuan. It was suitable for users who needed to switch between different focal lengths for ultra-wide-angle shooting. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
What are the visual effects when looking through a concave lens in a cartoon?
When looking through a concave lens in a cartoon, you'd typically notice that objects seem farther away and maybe a bit blurry at the edges. This is because concave lenses cause light rays to diverge, creating these visual effects.
Distortion correction of fish-eye lens
Fish-eye lens distortion correction aims to reduce or eliminate the image distortion effect caused by fish-eye lenses. When correcting the distortion of the fisheye lens, the core was to solve a "good" remap matrix, which rearranged some of the original image's pixel-points (or intervening points) and "pieced" them into a rectangular image."Good" was linked to the final requirement, and different tasks often used different correction/distortion solutions. For example, in the smart security industry, whether it was a monocular camera or a monocular camera, the images captured would have distortions, which was the same as the distortion correction principle of a fisheye camera. For monocular cameras, in order to obtain the corresponding relationship between the camera's coordinate system and the three-dimensional world coordinate system, the barrel distortion and pillow distortion of the camera needed to be corrected. For binocular cameras, in order to do epipolar line alignment and realize depth estimation, the output of the two cameras needed to be transformed into the same coordinate system. Teacher Zhang Zhengyou's chessboard correction method estimated the internal and external parameters and distortion coefficient of the camera through the position coordinates of the marker, and then calculated the remap matrix. This method had a good correction effect for monocular and binocular cameras. In terms of practical operations, fisheye correction can also be performed using python language (only relying on the opencv-python package and numpy package), and fisheye distortion correction can also be performed from code examples such as PILimport Image. In addition, the distortion correction function based on digital image processing was also applied to the fisheye lens correction. This solution required rearranging the arrangement of the elements, but for the ultra-wide system where the edge image quality itself was a big problem, it might lead to the image quality of the most edge area being worse. Some equipment would use the image field redundant design and the sensor to perform the redundant matching of the elements to reduce the side effects of the digital correction. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Full circle fish-eye lens
The reference did not mention anything about the full round fisheye lens. Sorry, I don't know how to answer based on the information I found. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>