CCTV Lens Questions

1. What is CCTV ?

CCTV means Closed circuit Television, it consists of picture collection, signal transfer, monitoring display and control unit. CCTV Lens is part of CCTV

2. Where is CCTV and CCTV lens used for ?

Most of CCTV surveillance will be used at hotel CCTV, hospital CCTV, airport CCTV, safe city CCTV, banks CCTV, factory CCTV etc., the CCTV lens will plays an important role at picture imaging.

3. What is CCTV Lens?

It's lens for CCTV system and put on CCTV camera, the

CCTV lens

includes security lens and machine vision lens etc.

4. Type of CCTV lens ?

Long focal length 35mm film,90mm above
Standard Length 35mm film,50mm
Wide focal length 35mm film,28mm below
Fisheyes lens

Fixed Fixed focal length With Iris & W/O Iris
Vari-focal Adjustable length Manual Iris & DC Iris

1)Fixed Lens:Focal length fixed and with Iris, W/O Iris type.
With Iris:The Iris is adjustable according to enviroment.The aperture can be adjustaed by manual or direct current. Manual Iris is adjustable by hand and DC Iris is controlled by micro motors.
W/O Iris:also called fixed irs, this CCTV lens is used for constant lighting or for camera which has E.S
2)Vari-focal Lens:Focal length is adjustable to amplyfy the object. 6x and 10x CCTV
lens is common used.
Manual Iris and DC Iris CCTV lens
Manual Iris:Adjustable at focal length, focus, Iris.
DC Iris:Adjustable at focal length, focus.

5. Type of controlling

Fixed CCTV lens
Vari-focal length CCTV lens
Motorized zoom lens

6. Back focal length

C: 17.526
CS: 12.5
CS mount CCTV lens can match CS camera
C mount CCTV lens match C camera
C mount CCTV lens match CS camera with 5mm adaptor
CS mount CCTV lens can't match C camera

7. What is size of CCTV lens?

1. 1/4 sensor size
2. 1/3 sensor size
3. 2/3 sensor size
4. 3/4 sensor size

8. What is ND filter?

ND filter for CCTV lens is to eliminate the light getting through the lens, which will help to prevent diffraction.

9. What is IR ?

The visible light is sufficient at daytime and infrared light enough at night vision. The visible light is less at night time, thus you can't see anything clearly without lighting. But infrared light is sufficient now with long length, which will help to put imaging onto the focal plane. Thus you will make a clear imaging at night vision by using of infrared lighting. So the CCTV lens must have infrared when there is night vision required.

10. What is resolution of CCTV lens ?

Decided by how many of the same width line pairs within 1mm you can see. A good CCTV lens can make you see a clear picture if you amplify the picture.

11. What is coating of CCTV lens?

We know there will be 5% light reflected back if the light getting through the CCTV lens, in order to eliminate such phenomenon, the coating is required. The multi-layer coating and single layer coating, the layers coating and one time layer coating will leading to different imaging. The more layers and both sides coating will leading to a good CCTV lens imaging.

12. What is status of CCTV lens in the world?

The CCTV lens can tracking back to Germany and developed in Japan, then Korea, Taiwan also have good technology to promote. During 1990s, China market CCTV lens speeded up and with high technology; China CCTV lens has very high level comparing with Japan, Taiwan, Korea CCTV lens, especially the IR CCTV lens, China market has very good level.
For motorized zoom lens, Japan still has reputated experience and quality, so China market needs work hard at zoom lens.

13. How to determine a good CCTV lens?

A. Multi-layer coating: this will leading to good imaging.
B. Big aperture: big aperture is good CCTV lens, which is difficult to make
C. Warranty time: long warranty time might be a good CCTV lens.
D. Housing designing: very beautiful design reflect good CCTV lens
E. Box and packing: high level CCTV lens should have good packing, anti-shake etc.
F. After-sale-service: good lens supplier might have good service

14. How to select good CCTV lens supplier?

A. Reputated suppliers with good service
B. Honest supplier
C. Not only cheap lens is good for you, which might leading you bad service and maintenances
D. Friends suggestion is very good idea
E. 3-5 years warranty time is good selection CCTV lens