Dalsa Falcon 4-CLHS Series, User Manual

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78 • Additional Reference Information Falcon™ 4 -CLHS Series
Additional Lens Parameters (application specific)
There are other lens parameters that are chosen to meet the needs of the vision application. These
parameters are independent of the Linea Lite GigE (assuming that the Lens Mount and Lens Sensor
Size parameters are correct, as previously covered in this section). A vision system integrator or
lens specialist should be consulted when choosing lenses since there is a tradeoff between the best
lenses and cost. An abridged list of lens parameters follows
– all of which need to be matched to
the application.
• Focal Length : Defines the focus point of light from infinity.
See Camera Specifications — Back Focal Distance .
• Field of View : A lens is designed to image objects at some limited distance range, at some
positive or negative magnification. This defines the field of view.
• F-Number (aperture) : The lens aperture defines the amount of light that can pass. Lenses
may have fixed or variable apertures. Additionally, the lens aperture affects Depth of Field
which defines the distance range which is in focus when the lens is focus at some specific
distance.
• Image Resolution and Distortion : A general definition of image quality. A lens with poor
resolution appears out of focus when used to image fine details.
• Aberrations (defect, chromatic, spherical) : Aberrations are specific types of lens faults
affecting resolution and distortion. Lens surface defects or glass faults distort all light or
specific colors. Aberrations are typically more visible when imaging fine details.
• Spatial Distortions : Describes non-linear lens distortions across the field of view. Such
distortion limits the accuracy of measurements made with that lens.