mvBlueGEMINI Technical Manual (EN) v
1.2.2
APPENDIX
-
CHOICE
OF THE RIGHT LENS AND LIGHTING SYSTEM
42
10.4
Choice of the right lens and lighting system
10.4.1
Find the correct lens
Lenses are the starting point of the image processing signal path and shape the light information.
The better the optics and the more time you've invested in this issue, the better the source material
for the image processing. In the following you will find an overview of the essential properties, sizes
and contexts.
10.4.1.1
Limits and settings of a lens
Image field size
With the image filed sizes you can extract first information about the boundary conditions of an
image. Here, the focal length of a normal lens corresponds to the diagonal of the image field.
For example, an 8 mm lens behaves like a wide angle lens in combination with a 1 inch sensor. In
contrast, the same lens behaves like a telephoto lens in combination with a 1/4 inch sensor. For
industrial purposes, sensor sizes from 1 inch and smaller are common.
Image field
Diagonal
4/3 inch
17.3 mm * 13.0 mm
23 mm
1 inch
12.8 mm * 9.6 mm
16 mm
2/3 inch
8.8 mm * 6.6 mm
11 mm
1/1,8 inch
6.7 mm * 5.4 mm
8,61 mm
1/2 inch
6.4 mm * 4.8 mm
8 mm
1/3 inch
4.8 mm * 3.6 mm
6 mm
1/4 inch
3.2 mm * 2.4 mm
4 mm
Components of a lens
Using a lens, the
focal length
defines the image angle and for this reason the scale between
object and image.
You can adapt two properties of the lens:
Focus
o
a sharp image is possible even with different object distances
o
a scale on the lens indicates distance between object and image (from the minimum
distance to infinity)
o
a closer focus is possible using spacers
