Industrial Cameras and Lenses
Lens model, data + power interface, focusing of fixed-focus lens, depth of field, depth of field, aperture, camera, lens selection
Lens model
- C, CS series: The C and CS interfaces of the camera lens are very similar, their interface diameter and thread pitch are the same, only the flange distance is different. The flange distance of the C interface is 17.5mm, and the flange distance of the CS interface is 12.5mm. Therefore, for a CS-mount camera, if you want to connect a C-mount lens, you only need a 5mm thick CS-C conversion ring.
- M series: M12 interface, the number 12 corresponding to this interface refers to the interface diameter is 12mm. Due to the small diameter, this type of interface is often used on tiny industrial cameras, such as the lenses commonly used in cameras on drones.
- other.
Data + power interface
- Common data and power interfaces include USB, CoaxPress (interface card is required: different from the acquisition card, it is just a transfer station for the data collected by the camera, it will not do any processing on the data, it will directly store the data in the main register) , CameraLink (requires a frame grabber, does not support hot swap, will damage the camera!), Gige interface, etc.
Focusing of fixed focus lens
- In most cameras, the CCD is fixed, and the focus is achieved by moving the distance between the entire lens and the imaging surface (the physical focal length of the lens remains unchanged, which is also the principle that fixed-focus lenses can be adjusted).
depth of field
- Definition 1: Depth of Field (DOF) refers to the range of distances between the front and back of the subject measured by imaging that can obtain clear images at the front of the camera lens or other imagers. Aperture, lens, and the distance from the focal plane to the subject are important factors affecting depth of field.
- Definition 2: After the focus is completed, the distance of the clear image presented in the range before and after the focus, this range before and after is called the depth of field.
- Definition 3: There is a space of a certain length in front of the lens (before and after the focal point). When the subject is located in this space, its image on the film is exactly between the same circle of confusion . The length of the space where the subject is located is called the depth of field. In other words, for the subjects in this space, the blurring degree of the image presented on the negative plane is within the limited range of the permissible circle of confusion , and the length of this space is the depth of field.
depth of field
- Lens aperture: The larger the aperture, the smaller the depth of field; the smaller the aperture, the greater the depth of field;
- Lens focal length: the longer the focal length of the lens, the smaller the depth of field; the shorter the focal length, the greater the depth of field; (the depth of field of the telephoto lens is short)
- Shooting distance: The farther the distance, the greater the depth of field; the closer the distance, the smaller the depth of field.
aperture
- The size of the aperture is described by the f value, which means how much it is open, which affects the amount of light entering the lens. The aperture value is f/2.0, which means that it is opened by 1/2. Common aperture values are as follows:
- A picture intuitively feels the relationship between aperture and depth of field:
camera, lens selection
- Pay attention to the following four points:
1. Working distance (WD): The distance from the outermost end of the lens to the measured object.
2. Field of View (FV): The size of the area actually captured.
3. Angle of View (FOV): Affects the theoretical field of view.
4. Optical magnification (Magnification, B): Divide the chip size by the field of view;
reference
https://mp.weixin.qq.com/s/wIKDmMc37cHCrKR-V13g_g
http://www.360doc.com/content/12/0413/15/7423456_203315678.shtml