Why is the lens 24 focal lengths?
There were several reasons for the existence of the 24-focal length: - ** Portrait shooting **: It was once called the "private eye" and was suitable for indoor portraits. However, this focal length was more difficult to control, and the price was not advantageous. Compared to the 28 and 35 focal length lenses, such as the Sima 351.4 (there were multiple bayonet mounts), the Sony28F2, 352.8, 351.8, Canon 35F2IS, Tenglong 351.4, Nikon 281.8G, and 351.8G, these lenses were priced at around 4000 yuan. The 24 fixed-focus lens was more expensive and had less choices. For example, Canon, Nikon, and Sony241.4 were priced at around 10,000 yuan. Other than that, there were only a few choices, such as the Sima 241.4 (around 4800 yuan) and Nikon 241.8 (around 4500 yuan). The number of photographers who would use 24 focal lengths to shoot portraits was also less than that of photography enthusiasts who used 35 focal lengths. - ** Landscape photography **: It used to have some advantages when shooting the Milky Way in landscape photography, but now there are a wider range of 201.4, 201.8, and 141.8 focal lengths to choose from. For non-galactic scenery photos, small aperture lenses such as 16 - 35, 14 - 24, 12 - 24, etc. were more suitable than 241.4. However, in the big three-dimensional lens, the 24 end of the 24 - 702.8 lens can replace the 24 1.4 in some cases. - ** Street sweeping **: The recognized focal length for street sweeping is 50, followed by 35 and 28. 24 focal length is less used for street sweeping, and 24 1.4 focal length lens is heavy and inconvenient to carry. - The 24 - 70mm f2.8 lens is a "standard zoom" lens with 24 focal lengths. It is practical, commonly used, and irreplaceable. It could be used for documentary topics and could restore the original appearance of the subject. It covered many commonly used focal lengths from small wide angle to medium focal length, such as 24, 28, 35, 50, and 70. It was suitable for daily high-frequency use. It was difficult to find a replacement lens, but it could replace many other lenses. Read more exciting novels for free
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>
How many focal lengths are used to monitor the fence?
For places with a large depth of field and a wide range of viewing angles like walls, cameras with 6 - 8mm lenses were generally used for monitoring. <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>
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>
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>
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>
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. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Small focal length lens sweeping the street
Small focal length lens (less than 35mm focal length) was a wide-angle lens. It was featured by a wide angle of view and could shoot large areas of scenery, but the distortion was large and easy to produce distortion effects. When sweeping the streets, this kind of lens could record the overall style of the street, including the surrounding buildings, many people, and rich scene elements. However, due to the distortion problem, the image of the character may be distorted when shooting, especially near the edge of the picture. Therefore, if a person was the main subject of the shot, one had to pay special attention to the composition and angle of the shot. Try to avoid the person from being at the edge of the picture. If you wanted to highlight the sense of space on the street, the lively atmosphere of the crowd, or the grandeur of the building, a small focal length lens was a good choice. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to exercise the focal length of the camera lens
You can practice using various focal lengths to understand the characteristics of each focal length of the lens, understand the angle and perspective relationship, and make use of the different depth of field of each focal length. For example, using a telescope (A lens with a focal length of more than 200mm) When shooting, you can feel that it has little sense of distance and has a compression effect.(85mm-135mm focal length lens) The perspective closest to the human eye, can accurately reflect the shape of the subject, can be used for portrait photography; Wide-angle lens (focal length below 35mm lens) can emphasize the sense of distance; Standard lens (focal length around 50mm lens) The shooting effect is extremely natural, without exaggeration. During the shooting process, he constantly summarized the differences in the effects of the images shot by different focal length lenses, which helped to train the focal length of the camera lens. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</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>