The focal length of a direct-focus camera
In direct-focus photography, when the eyepieces of the telescope were removed, leaving only the main mirror, the lens of the DSLR was also removed to expose the LCD sensor, and then the telescope was directly connected to the DSLR (may require an M42 ring). At this time, the focal length of the telescope's main mirror was the focal length of the lens. For example, when using the MK20240 for direct-focus photography, the focal length was 2400mm, so the focal length of the lens was 2400mm. Read more exciting novels for free
The focal length of the surveillance camera
In an optical system, the focal length of the surveillance camera was the distance from the optical center point of the lens to the camera's CCD-based/CMOS-based sensor. It can also be understood as the distance from the center of the lens to the focal point of the light when parallel light is incident. The size of the focal length determined the image size, field of view, and depth of field of the surveillance image. Generally speaking, the larger the focal length, the farther the view, and the smaller the field of view. The smaller the focal length, the closer the view, and the larger the field of view. The focal length of mainstream surveillance cameras was generally 2.8mm, 3.6mm/4mm, 6mm, 8mm, 12mm, 16mm, etc. Some even had a zooming function. Cameras with different focal lengths are suitable for different monitoring ranges. For example, for situations where the monitoring range is small and the viewing angle is large, such as a family living room, small shops, etc., you can choose a surveillance camera with a smaller focal length.(For example, a 3.6mm or 4mm focal length camera can have a viewing angle of 75°-90 °, an effective monitoring distance of more than 5 meters, and can cover 40 - 80 degrees of space); for a larger monitoring range (such as a space of 10m * 10m), you need to choose a surveillance camera with a larger focal length. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
Staircase camera focal length
For a relatively narrow environment such as stairs, a 2.8mm focal length camera could generally be used. Its field of view was larger and the range that could be seen was the largest. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
camera focal length factor
For digital cameras, because the area of their CCDs or sensors was smaller than that of traditional 135 cameras (35mm full-frame), when using the same lens, the imaging area was smaller than that of a film camera, resulting in fewer scenes falling on the imaging element than traditional 135 cameras. This gave rise to the concept of focal length coefficient. The focal length coefficient was calculated as the ratio of the length of the film to the length of the corresponding side of the CCD. For example, if the film is calculated as 24mm, the corresponding side length of the CCD-side is 12mm, and the coefficient is 2. When using lenses on different frame cameras, the focal length needed to be converted by a factor. For example, the Canon APS-C camera needed to be multiplied by a factor of 1.6. For example, a 100mm fixed-focus head hung on the APS-C body would have an equivalent focal length of 160mm, while the Canon APS-C classic head's actual focal length of 18 - 135mm would be 28 - 216mm. The focal length coefficient made it so that when the lens was used on different frame cameras, although the angle of view had an equivalent change, the depth of field and perspective effect were still the same as the original lens. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
The difference in the focal length of the surveillance camera
For surveillance cameras, there were many differences in focal length: 1. ** Image size **: The focal length affects the image size of the captured image. 2. ** Field of view **: - The larger the focal length, the smaller the field of view. With the lens as the apex, the angle formed by the two edges of the largest range of the object image through the lens would be smaller. The range of the viewing angle would be smaller, but the relative details would be clearer. - The smaller the focal length, the larger the field of view, and the larger the range of view, but the lower the degree of recognition. 3. ** Depth-of-field **: Depth-of-field refers to the distance between the front and back of the object being photographed when the camera lens can obtain a clear image. The depth of field was different at different focal lengths. 4. ** Surveillance Distance **: - The larger the focal length, the farther the surveillance camera could shoot. It was suitable for monitoring distant targets or large areas, such as outdoor rectangular areas. - The smaller the focal length, the closer the surveillance shooting distance. It was suitable for monitoring closer targets or areas with a small range and a large viewing angle, such as indoor square areas such as family living rooms and small shops. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to choose the focal length of the surveillance camera
The following aspects could be considered when selecting the monitoring focal length: * * 1. Choose according to the monitoring range ** 1. * * Small monitoring range and large viewing angle **: For example, in a family living room or small shops, you can choose a surveillance camera with a smaller focal length. For example, a camera with a focal length of 3.6mm or 4mm can have a viewing angle of 75 °-90 °, an effective monitoring distance of more than 5 meters, and can cover a space of 40 - 80 square meters. 2. * * Large monitoring range (10m * 10m or more)**: You need to choose a surveillance camera with a larger focal length, but a larger focal length will reduce the monitoring angle. To achieve complete monitoring, you can consider using a cloud platform ball machine or installing multiple surveillance cameras. 3. * * Surveillance range is fixed and very far away (such as monitoring a parking lot 30 meters away)**: You need to choose a camera with a larger focal length, such as a surveillance camera with a 12mm or higher. * * 2. Choose based on the usage scenario ** 1. * * Narrow space (such as garage, storage room, etc.)**: It is recommended to choose 2.8mm focal length, and the best monitoring distance is within 3 meters. 2. * * Home or small shop environment **: It is recommended to choose 4 mm focal length, and the best monitoring distance is 3 - 5 m. 3. * * Family courtyard, balcony, doorway, etc. **: 6mm focal length is recommended. 4. * * A wide outdoor area without high requirements for details **: A camera with a 4mm focal length is more suitable. 5. * * Need to capture detailed information from a distance (such as license plate number or facial features)**: A camera with an 8mm focal length is more suitable. In addition, the field of view of the surveillance camera is determined by the width, height, and distance from the surveillance camera. Once the scene to be monitored is determined, the correct choice of the focal length of the lens is also affected by the size of the scene to be monitored, the distance between the camera and the scene, and the size of the camera imagers (such as 1/3 ", 1/2", 2/3 "or 1 "). The calculation method is: f = vD/V or f = hD/H (where, f represents the focal length. When f = vD/V, v represents the vertical height of the CCD-target surface, D represents the distance from the lens to the scene, and V represents the height of the object being observed; when f = hD/H, h represents the horizontal width of the CCD-target surface, D represents the distance from the lens to the scene, and H represents the width of the object being observed). After calculating the focal length value, if there was no corresponding focal length lens, one could choose a similar model according to the product catalog. Generally, one would choose a smaller lens than the calculated value, so that the viewing angle would be larger. <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 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>
What's the use of the focal length of the surveillance camera?
The focal length of the surveillance camera had the following effects: 1. ** Deciding the monitoring angle and line of sight range **: The smaller the focal length, the wider the visual and line of sight angle of the camera, and the wider the coverage of the area. Conversely, the larger the focal length, the narrower the shooting angle. For example, a 2.8mm lens had a monitoring angle of 102°, while an 8mm lens had a monitoring angle of only 38°. 2. ** Affects the monitoring distance **: The smaller the focal length value, the closer the monitoring distance will be; the larger the focal length value, the farther the monitoring distance will be. For example, the clearest point of a 2.8mm lens was about 3 meters and the monitoring distance was 5 meters, while the clearest point of an 8mm lens was about 12 meters and the monitoring distance was 24 meters. 3. ** Adaptability of the associated monitoring scene **: Different focal lengths are suitable for different monitoring scenes. The 2.8mm lens was more suitable for scenes such as elevators and small rooms where the distance requirement was not high and the angle requirement was large; the 4mm lens could be used in the living room and bedroom of ordinary families; the 6mm lens was suitable for narrow corridors; and the 8mm lens was suitable for monitoring long walls or roads. 4. ** Impact on the imaging effect and image quality **: If the focal length is too small, the monitoring area will be wide, but the image will be small and the details will be unclear; if the focal length is too large, the monitoring area will be narrow, and the image will be large, and the overall monitoring scene may not be visible. 5. ** Regarding the price of surveillance cameras **: Under normal circumstances, when the focal length is not much different, the price of surveillance cameras is basically the same. However, if the focal length is large to a certain extent, the price of the camera will double, which is similar to the lens of a camera. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
How to choose the focal length of the home surveillance camera?
When choosing the focal length of the home surveillance camera, you can refer to the following points: 1. ** Surveillance Scene * - ** Narrow space (such as garage, storage room, etc., the best monitoring distance is within 3 meters)**: You can choose 2.8mm focal length to obtain a larger field of view and a larger monitoring range. - ** Home or small shop (optimal monitoring distance 3 - 5m)**: 4mm focal length is more suitable, wider field of view, can capture a large range of scenery, can meet the basic monitoring needs, but the picture clarity and detail display ability is average, may need a higher resolution to make up for. - ** Family courtyard, balcony, door (optimal monitoring distance 5 - 10m)**: It is recommended to choose a 6mm focal length. Its field of view and clarity are more balanced. It can provide a relatively wide field of view, and can ensure the clarity and details of the picture. The resolution requirement is also relatively moderate. - ** Open areas (such as parking lots, playgrounds, etc.)**: 4mm focal length can be used to monitor large areas, but it may not be enough in terms of image clarity and details. If you need to cover a wider area (such as parking lots, factory workshops, etc.), a 6 - 8mm focal length lens is also a good choice. If you want to monitor a very long distance (such as a parking space 30 meters away), you may need a camera with a focal length of more than 12 mm. 2. ** budget and technical requirements **: The price of high-resolution cameras is higher, and the requirements for storage and processing equipment are also higher. If the budget is limited or the technical conditions do not allow it, comprehensive consideration should be taken when selecting the focal length. For example, you cannot choose a focal length that requires too much resolution and cannot be met by your own equipment. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>
What's the focal length of the Apple 14pro's camera?
There were two types of telephoto lenses for the Apple 14 Pro. The 12-million-pel 2x telephoto lens (achieved through a four-in-one sensor) had a focal length of 48 mm, and the 12-million-pel 3x telephoto lens had a focal length of 77 mm. <a href="/?from=ask_words" style="color:red" target="_blank">Read more exciting novels for free</a>