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kb:aoi:lense-selection

Lens Selection

1. Calculation of max. focal length

Lens must be ⇐ than the calculated value

          Distance x CCD_h
  FL_h = -----------------
           Height + CCD_h
          Distance x CCD_w
  FL_w = -----------------
          Height + CCD_w
  • Distance … Distance between test surface and front of the lens
  • Height … vertical dimension of the area to be displayed
  • Width … horizontal dimension of the area to be displayed

2. CCD-Format

Sensor-Format Height (mm) Width (mm)
1/4“ 2,40 3,20
1/3” 3,60 4,80
1/2.5“ 4,20 5,60
1/2” 4,80 6,40
2/3“ 6,60 8,80
1” 9,60 12,80

3. Minimum Working Distance

MOD = Minimum Object Distance

If the MOD of a lens is greater than the actual distance to the object, an intermediate ring between the lens and the camera can help.

Focal Length
Ring/Tube 8 mm 12 mm 16 mm 25 mm
0.5 12 .. 31 cm 22 .. 54 cm 41 .. 129 cm
1.0 8 .. 15 cm 17 .. 28 cm 32 .. 66 cm
1.5 6 .. 10 cm 14 .. 20 cm 27 .. 45 cm
5.0 2 .. 3 cm 7 .. 8 cm 14 .. 16 cm
10.0 9 .. 10 cm

Example

Lens with focal length = 16 mm and MOD = 300 mm

  • Without intermediate ring → MOD = 300 mm
  • Intermediate ring 0,5 mm → MOD = 220 mm
  • Intermediate ring 1,0 mm → MOD = 170 mm
  • Intermediate ring 1,5 mm → MOD = 140 mm
kb/aoi/lense-selection.txt · Last modified: 2018/10/25 16:18 by bence.bartho