Canon m50 longest focal length lens
Canon M50 lenses mentioned that 100 - 400mm or 200 - 400mm could be used for special needs (such as when shooting birds that required an ultra-long focal length lens). There was no mention of a longer focal length lens specifically for the M50, so the 200 - 400mm lens was currently the longest focal length lens known. Read more exciting novels for free
How to adjust the focal length of the Canon camera lens
Different types of Canon cameras had different ways of adjusting the focal length of the lens: - ** Card camera or telephoto camera **: You can press the buttons marked with W and T on it, or it may be a ring with a small handle on the shutter button that can be twisted and marked with W and T nearby to adjust the focal length. - ** DSLR or single-camera **: Turn the zoom ring on the lens to adjust the focal length of the lens. - ** Some Canon cameras **: After focusing in the AF-mode, adjust the lens focus mode to the MTF-mode to lock the focus and re-compose the picture; you can also set the camera to the live-view mode.(Liquid crystal display viewfinder mode), directly click on the touch screen to select the focus; or turn the AFF/MV switch on the lens to MV, and turn the focus ring on the lens to manually focus; or in the autofocus mode, you can use the four-point cross star on the upper right edge of the back of the camera, press the dial wheel behind the shutter to change and select the focus. In addition, on the back of some models (such as the 70D), there was a magnifying button (the icon was in the shape of a magnifying glass). Pressing it could magnify the image by a certain number of times. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
the focal length of a camera lens
The focal length was the division of the focal length of the lens. It was generally divided into super wide angle, wide angle, standard, medium focal length, medium telephoto, telephoto, and super telephoto. Take a 35mm camera (135 camera) as an example: a lens with a focal length below 20mm is an ultra-wide-angle lens; a lens with a focal length of 21mm-40mm is a wide-angle lens; a lens with a focal length of 41mm-60mm is a standard lens; a lens with a focal length of 61mm-100mm is a medium-focal lens; a lens with a focal length of 101mm-180mm is a medium-long focal lens; a lens with a focal length of 180mm-300mm is a telephoto lens; A lens with a focal length of 301mm or above was a super telephoto lens. Different focal lengths had different characteristics and applicable scenes. For example, the ultra-wide angle lens had a wide angle of view, which was suitable for shooting large scenes such as scenery and architecture; the standard lens was close to the human eye's angle of view, with very little distortion, which was more suitable for documentary photography; the telephoto lens could achieve background blurring, compress space, and highlight the main body, but the scene was small, so it was difficult to blend the background with the main body well. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
90 focal length lens group photo
When taking group photos, a 90mm focal length lens was a more suitable choice. The standard lens had many advantages when taking group photos, such as the smallest distortion and the closest to the human eye's visual perception. When using a 120 medium format 6×7 camera to take a group photo of more than 500 people, using a 90mm lens could achieve better results. However, when using this focal length lens to take a group photo, one also had to consider other factors such as shooting distance, aperture, shooting time, queue position, etc., in order to take the ideal group photo. For example, it is recommended to choose soft natural light when shooting, such as 9 - 10 a.m. or 4 - 5 p.m.(It needs to be adjusted according to the season and regional differences). It is best to use a cloudy morning, and the direction of the light is best to be in the light. In terms of queue position, when there are more people, they can be arranged in a square array (for example, 50 - 100 people can be arranged in 4 - 5 rows). The height of the front and back rows should be reasonably arranged by chairs, stools, steps, etc. to avoid blocking. It is recommended to use a small aperture such as F11 or F16 (different cameras may have different aperture ranges). <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The relationship between the lens and the focal length
The focal length was a key characteristic of a photographic lens. The two were closely related and had many effects on the shooting: * * 1. Relationship between lens type and focal length ** 1. * * Wide-angle lens ** - A lens with a focal length of less than 35mm was a wide-angle lens. This type of lens had a wide angle of view and was suitable for shooting scenery, buildings, and other scenes that required a large angle of view. For example, when taking pictures of vast natural scenery or magnificent buildings, the wide-angle lens could bring more scenes into the picture. 2. * * Standard Shot ** - A lens with a focal length of about 50mm was considered a standard lens. Its angle of view was close to what the human eye could see, and it was often used for portraits and everyday photography. When using a standard lens to shoot a portrait, the proportions and space of the person were more natural. 3. * * Telephoto lens ** - Lenses with a focal length of more than 70mm were considered telephoto lenses and were suitable for long-distance shooting, such as wild animal photography and sports photography. A telephoto lens could make a distant subject look bigger in the picture, as if it was closing the distance between the photographer and the subject. * * 2. The effect of focal length on the lens shooting effect ** 1. * * Perspective * - The shorter the focal length, the wider the angle of view of the lens, allowing it to capture a wider scene. For example, when using a lens with a smaller focal length to shoot a city street, it could cover more street buildings and people. On the contrary, the longer the focal length, the narrower the field of view, which could make distant objects look closer. For example, when a telephoto lens was used to shoot wild animals, it could highlight the main body of the animal while blurring the background. 2. * * In terms of depth of field ** - A lens with a shorter focal length usually has a deeper depth of field, which means that a larger area of the picture will remain clear. This was very useful in landscape photography, such as using a wide-angle lens to shoot a large sea of flowers, from the flowers nearby to the mountains in the distance. The long focal length lens would produce a shallow depth of field, blurring the background and helping to highlight the subject. In portrait photography, the long focal length lens could clearly highlight the main character and blur out the messy background. 3. * * X-ray Transfiguration ** - Wide-angle lenses (short focal length) were prone to perspective distortion, making the object in the picture look farther or flatter than it actually was. For example, when shooting a person at close range with a wide-angle lens, the proportion of the facial features of the person may be out of balance, and the parts close to the lens (such as the nose and mouth) may appear larger than normal. The long focal length lens could better maintain the proportional relationship between the objects and reduce distortion. It was more suitable for shooting scenes that needed to accurately represent the shape of people or objects. * * 3. The relationship between the focal length indicator and the lens type ** - If the focal length label on the lens had two numbers, it meant that the lens was a zoom lens, and its focal length covered the focal length between the two numbers. For example, the 17 - 40mm logo meant that this was a zoom lens, and the focal length varied between 17mm and 40mm. If the focal length indicator on the lens only had one number, it meant that the lens was a fixed-focus lens. For example, a lens with a focal length of 50mm was a fixed-focus lens. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The focal length and characteristics of a photographic lens
The focal length was a measure of the concentration or dispersion of light in an optical system. The distance between the focal point and the center point of the mirror was the focal length, and the unit was "mm." If there was only one number on the lens, it was a fixed-focus lens. If there were two numbers, it was a zoom lens. Lenses with different focal lengths had different characteristics and functions: 1. ** Super wide-angle lens (focal length less than 24mm)**: - [Special characteristic: Large viewing angle] - [Function: It is suitable for shooting large scenes such as scenery and architecture. It can accommodate more elements in the picture, but the proportion of each element in the picture is small. At the same time, it is easy to produce distortion effects. It is difficult to control the effect in close-up shots.] 2. ** 24mm/28mm wide-angle lens **: - [Special characteristic: A wide viewing angle.] - [Function: Commonly used for shooting scenery, architecture, and other large scenes. It can also include many objects, but it may include unnecessary elements during composition, causing the picture to be messy.] 3. ** 35mm-85mm standard lens **: - [Special characteristic: The shooting effect is close to what the human eye can see. It looks natural.] - [Function: It is widely used in portrait shooting, with 35mm, 50mm, and 85mm being common focal lengths.] 4. ** 85mm lens (fixed-focus lens is outstanding in portrait photography)**: - [Special characteristics: Shooting angle of 28 degrees. With a large aperture, the background can be simplified, the character can be highlighted, and the background blurring effect is good. The distance from the whole body to the close-up is about 1.5 meters to 5 meters. The image quality is good, but the angle of view is fixed.] - [Effect: Excellent performance in portrait photography, regarded by many professional photographers as the king of focal length.] 5. ** Telephoto lens above 200mm **: - [Special characteristics: Narrow angle of view, can zoom in on distant objects, can perform a reduction process on the image to eliminate messy elements, has a strong sense of background compression, can make the main body and the background closer in perception, and the longer the focal length, the less obvious the face distortion effect. When shooting a portrait, the facial features will be slightly flattened.] - [Usage: Commonly used for shooting birds, sports events, and other long-distance subjects.] <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to measure the focal length of a laser lens
The focal length of the laser lens was measured as follows: 1. ** Experimental measurement method ** - ** Roughly measure the focal length of the concave lens (uncertainty not calculated)**: clearly image an object in the distance (such as the scenery outside the window or a lit table lamp more than 5 meters away in the room) on the image screen. Move the lens back and forth, and measure the distance between the concave lens and the image screen with a steel ruler. This distance is the focal length of the lens. The reading is accurate to millimeters. It is not estimated below 1 mm. - ** Measuring the focal length of the concave lens by the two-time imaging method (estimated reading: 1/2 mm, uncertainty not calculated)**: Place the object screen and the image screen on the optical bench, so that the distance between the object screen and the image screen is greater than 4 times the focal length of the lens. The distance between the object screen and the image screen was kept constant, and the concave lens was moved. The positions of the concave lens corresponding to the magnified image and the reduced image were recorded clearly on the image screen, and the focal length of the concave lens was calculated after multiple measurements. - ** Measuring the focal length of a concave lens by auto-alignment ** - ** Manual reading (uncertainty limit 0.1mm, estimated reading 1/2 division value (mm))**: Put the light source, object screen, concave lens, and reflective mirror on the optical bench in turn, move the concave lens until a clear image is seen on the object screen (the method to determine that it is a self-aligned image depends on the specific experimental situation), and record the position of the object screen and the concave lens; then rotate the concave lens around the support by 180°, repeat the above measurement, and finally calculate the focal length and uncertainty of the concave lens. - ** Laser ranging (uncertainty limit 0.2mm, minimum indication value 1mm, no estimation)**: Similarly, place the light source, object screen, concave lens, and reflective mirror on the optical bench in order. Move the concave lens until a clear image appears on the object screen. Record the position of the object screen and the concave lens. Then rotate the concave lens 180° around the support and measure again to calculate the focal length. 2. ** Calculating using optical principles **: For an ideal thin lens, the formula can be used according to the curvature radius and refraction index of the lens.(f = \frac{(n -1) \times R}{2}\)(where <f> is the focal length,<n> is the refraction index of the lens material, and <R> is the radius of curvature of the lens). For thick lenses, the thickness of the lens and the curvature radius of the two surfaces need to be considered.(<frac{1}{f} = (n-1) (<frac{1}{R1} -<frac{1}{R2} -<frac{(n - 1)d}{nR1R2})>)>, where <R1> and <R2> are the curvatures of the two surfaces of the lens, and <d> is the thickness of the lens.) 3. ** Determined according to the characteristics of the laser resonant cavity **: In the laser system, the focal length of the laser resonant cavity is related to the mode radius and the optical wavelength of the laser crystal. The focal length of the thermal lens can be determined by measuring the output power of the laser, but this process involves the influence of the thermal effect of the laser on the parameters. 4. ** Use optical design software **: In modern optical design, professional optical design software can be used to help calculate the focal length. These software can simulate the path of light in the lens and accurately calculate the focal length. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to increase the focal length of the camera lens
To increase the focal length of the camera lens, the following methods can be used: 1. Use a telephoto lens: The focal length of a telephoto lens is larger. For example, a 50mm lens is considered a standard lens, and a 200mm lens is a telephoto lens. Using a telephoto lens can zoom in on distant objects and make the picture more full. This is the most direct way to expand the focal length. 2. Use a magnifying lens: The magnifying lens can be directly installed on the lens to double or more the focal length. For example, the focal length of the camera lens was 50mm. After installing a 100mm magnifying lens, the focal length of the camera could be expanded to 100mm, and the cost of this method was relatively low. 3. Use digital zoom: Most modern digital cameras are equipped with digital zoom, which uses software algorithms to magnify images without changing the focal length of the lens. However, this method will cause the quality of the image to deteriorate because it is achieved by cropped images. It is not recommended to use it often. 4. Use post-production software: If you don't have a large focal length lens or a magnifying lens, you can use post-production software (such as PowerPoint or Lighthouse) to simulate a large focal length effect by trimming and adjusting the image. However, this requires a certain amount of skill and experience, and is often used in creative photography. <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
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>
Projection lens simple test focal length
In fact, there were many methods to test the focal length of an optical system (including a projection lens). Based on different principles, the focal length test methods could be divided into three categories: The first type was based on the position of the image plane. The second type was to use the relationship between the magnifying power and the focal length to obtain the focal length value. The third method was to use the curvature of the converging beam to obtain the focal length. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>