Tube Length LT = flange focal length + lens extension (Camera flange length)
{!{!{LT=s'A_∞+∆s'-s'K}!}!}Tube Length
Example
Rodagon 4.0/80
Focal length f = 81 mm
Magnification β = 1/6
Flange focal length s’A∞ = 74.7 mm
Camera flange focal length s’K = 19.5 mm
Lens extension ∆s’ = f β = 81 mm/ 6 = 13.5 mm
Tube length LT = 74.7 mm + 13.5 mm - 19.5 mm = 68.7 mm
The calculated tube length LT can be achieved by using e.g.:
focus adapter FA22-40 22.0 mm
+ focus adapter extension 6.7 mm
+ 2x extension rings ZR20 40.0 mm
Total = 68.7 mm
Lens parameters scheme
Imaging Parameters
Schematic depiction of the imaging system and definition of variables used.
f = Lens focal length (mm)
S = Sensor length (mm)
L = Length of Region of Interest (ROI) of object (mm)
a = Object range (mm)
a’ = Image distance: Distance from sensor to HH’ (mm)
β = Magnification
w = Field angle
OO’ = Distance from sensor to measured zone (mm)
s’A = Flange focal length (mm)
∆s’ = Lens extension (mm)
LT = Tube length
A = Working distance (mm)
HH’ = Principal point distance (mm) (can lengthen or shorten OO’)
s’K = Camera flange length consisting of focus adapter series FA22 and extension rings series ZR (mm)
LO = Lens length (mm)