1. Classified according to appearance and function
2. Classification by lens installation
All camera lenses are threaded. There are two industry standards for CCD camera lens mounting, namely C mount and CS mount. The thread part is the same, but the distance from the lens to the photosensitive surface is different.
C mounting block: The distance from the lens mounting datum to the focal point is 17.526mm.
CS mounting block: Special C installation, at this time, the washer on the front of the camera should be removed before installing the lens. The distance from the lens mount datum to the focus is 12.5mm. If you want to mount a C-mount lens to a CS mount camera, you need to use a lens converter.
3. classified by camera lens specifications
Camera lens specifications should be based on the size of the camera CCD, the two should be corresponding.
That is, when the size of the CCD target surface of the camera is 1/2 inch, the lens should be 1/2 inch.
When the CCD target size of the camera is 1/3 inch, the lens should be 1/3 inch.
When the CCD target size of the camera is 1/4 inch, the lens should be 1/4 inch.
If the lens size is not consistent with the CCD target size of the camera, the viewing Angle will not meet the design requirements, or the picture will be out of focus and other problems.
4. Classification by lens aperture
The lens is divided into manual iris and auto iris, which are used with the camera. The manual iris lens is suitable for the application where the brightness is unchanged, while the automatic iris lens is also automatically adjusted when the brightness changes, so it is suitable for the application where the brightness changes.
There are two types of automatic aperture lenses: one is to transmit a video signal and power from the camera to the lens.
Mirror to control the aperture on the lens, called video input type, another type is the use of the camera’s DC voltage to directly control the aperture, called DC input type.
ALC automatic lens control on automatic aperture lens) adjustment is used to set the metering system, which can set the average brightness of the whole picture, or the brightest part of the picture (peak) to set the benchmark signal strength, which is used for automatic aperture adjustment. Generally speaking, ALC has been set in the factory and does not need to be adjusted. However, when the shooting scene contains a target with high brightness, the image of the bright target may cause the phenomenon of “white level clipping” and make the whole screen become white. In this case, ALC can be adjusted to change the picture.
In addition, the automatic aperture lens is equipped with an aperture ring, when the aperture ring is rotated, the light flux through the lens will change, the light flux is the aperture, generally expressed by F, its value is the ratio of the focal length of the lens to the aperture of the lens, that is, F = f (focal length) /D (the actual effective aperture of the lens), the smaller the F value, the larger the aperture.
With an automatic aperture lens, it is ideal for the following applications:
In very bright conditions such as direct sunlight, automatic aperture lenses can have a wide dynamic range.
When good focus over the entire field of view is required, an automatic aperture lens has a greater depth of field than a fixed aperture lens.
It is required to use an automatic aperture lens when the blur caused by light signal on bright light is minimal.
5. according to the lens field of view size classification
Standard lens: the Angle of view is about 30 degrees. In 1/2 inch CCD camera, the focal length of the standard lens is 12mm, and in 1/3 inch CCD camera, the focal length of the standard lens is 8mm.
Wide Angle lens: the Angle of view is more than 90 degrees, the focal length can be less than a few millimeters, can provide a wider view.
Telephoto lens: the Angle of view is within 20 degrees, the focal length can reach several meters or even tens of meters, this lens can magnify the impact of the photographed object in the long distance, but make the observation range smaller.
zoom lens: Also known as telescopic lens, there are manual zoom lens and electric zoom lens two types.
vari-focus lens: It is between the standard lens and the wide Angle lens, the focal length is continuously variable, can enlarge the distant object, but also can provide a wide view, so that the monitoring range increases. The zoom lens can be set to focus automatically on the minimum and maximum focal length, but from the minimum focal length to the maximum focal length, you need to focus manually.
Pinhole lens: The lens is a few millimeters in diameter and can be mounted stealthily.
6. from the lens focal length points
Short focal length lens: because of the wide Angle of incidence, can provide a wider field of view.
Medium focal length lens: standard lens, the length of focal length depends on the size of the CCD.
Long focal length lens: due to the narrow Angle of incidence, it can only provide narrow view, suitable for long distance surveillance.
Zoom lens: usually electric, can be used as a wide Angle, standard or telescopic lens.
SONY Auto focus camera FCB-EV9520L