Adept AdeptSight User Guide - Manual (Page 634)

Focal Length
the lens focal length. The size of the camera imaging element determines a scaling factor to
be applied to this relationship. The relationship is given in the following formula.
Camera Imaging
Formula for Focal Length
The formula for focal length is:
f S C H = ( ÷ )
where:
f = lens focal length in millimeters
S = camera scale factor (see the table Vision Basics - Resolution on page 632)
C = camera height (distance from front of lens to work surface)
H = height of camera field of view (same units as C)
The following figure illustrates these relationships and the meaning of the camera scale fac-
tor. In the two examples in this illustration, the field-of-view width and the camera-to-object
distance remain constant while two cameras with different size imaging surfaces are used. In
order to keep the image within the imaging surface on both cameras, different focal length
lenses must be used. By applying the correct camera scale factor for each camera (based on
the imaging surface size), the correct lens focal length can be determined.
AdeptSight User's Guide, Version 3.2.x, Updated: 8/23/2012
Page 634