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