how to choose the focus length for your cctv cameras?

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1.Knowing your CCD or CMOS size.Then reference the following table:

CCD size(inch) Horizontal wide(mm) Vertical high(mm)

1/4" 3.2 2.4

1/3" 4.8 6

1/2" 6.4 8

2/3" 8.8 11

1" 12.7 16

Horizontal wide use "W" to represent,vertical high use"H" to represent.

 

2.Getting know the about distance from the target object to the lens center.Use "D" to represent.

 

3.Use the following formula to calculate your focus length that needed.

f=wD/W or f=hD/H

f means focus length.

 

Notes:This might be the clear focus length to see the target object clearly.Not just "could see the target"

 

This article is reference to http://www.etown.cc/en/a/n/123.html