Introduction To Physical Parameters Of Optical Lenses
The focal length, also known as focal, is the measure of the aggregation or divergence of light in an optical system, referring to the distance from the center of the lens to the focus of the light gathering. Also is the camera, from the lens optical Center to the end of the film, CCD or CMOS imaging plane distance. Optical systems with short focal lengths have better ability to gather light than long focal optical systems.
The general industrial lens has a fixed focal length parameter, this parameter is the most important measure of the lens. The common focal length in the industry is: 4mm\6mm\8mm\12mm\16mm\25mm\35mm\50mm\75mm\100mm and so on, according to the different use distance, with different kinds of cameras, different visual field (FOV) needs, we can calculate the need to use the focal length. The method of calculation is referenced above.Optical Lenses
Different focal lengths, different distances with the same camera can be seen in the same field, in this case how to choose? It is generally recommended not to use small focal lengths in the imaging mode of the small-distance state, which can cause the image to appear relatively large physical distortion.Optical Lenses
Depth of field (DoF) is the range between the nearest position and the farthest position of an object in the case of allowable focusing. As can be seen from the above formula, the lens depth of field and aperture is closely related, and the lens depth of field and F # is proportional relationship, then you can see that when the lens has a relatively low light flux, it will have a relatively large depth of field, and vice versa.Optical Lenses