mvBlueGEMINI Technical Manual (EN) v
1.2.2
APPENDIX
-
CHOICE
OF THE RIGHT LENS AND LIGHTING SYSTEM
47
Figure 7 Setting level
The parameter h is usually not known. With the mvBlueGEMINI, h is usually very small.
For this reason, the formula without h is used in test setup concepts.
It should be possible to set every lens to infinity. In this case, the
Distance between lens and image = focal length
Therefore, each lens should be fixed in a different way. To avoid this, camera classes have fixed
distances, called
flange focal distance
. C-mount lenses, for example, have a flange focal distance
of 17.5 mm, which is independent from the focal length (CS-mount = 12.5 mm). With the help of
adapters, lenses with longer flange focal distances can be mounted on cameras with shorter
distances. This will not work vice versa because you will not reach infinity then.
The resolution - a little physics
Actually, you have to consider the
wavelength of the light
, because the light makes the image.
The wavelength of the visible light is between 0.4 µm and 0.6 µm.
The smallest imaged point results from the aperture which will never be smaller than 0.5 µm.
Realistic figures are between 2 µm and 5 µm.
B = 1.22 * 2 * λ * F / D
