System4f.effectiveFocalLengths

raytracing.System4f.effectiveFocalLengths(self)

The effective focal lengths calculated from the power (C) of the matrix.

There are in general two effective focal lengths: front effective and back effective focal lengths (not to be confused with back focal and front focal lengths which are measured from the physical interface). The easiest way to calculate this is to use f = -1/C for current matrix, then flipOrientation and f = -1/C

Returns:

effectiveFocalLengths – Returns the effective focal lengths in the forward and backward directions. When in air, both are equal.

Return type:

array

See also

raytracing.Matrix.focalDistances

Examples

>>> from raytracing import *
>>> # M1 is an ABCD matrix of a lens (f=5)
>>> M1= Matrix(A=1,B=0,C=-1/5,D=1,physicalLength=0,label='Lens')
>>> f2=M1.effectiveFocalLengths()
>>> print('focal distances:' , f2)
focal distances: FocalLengths(f1=5.0, f2=5.0)

This function has the same out put as effectiveFocalLengths() >>> f1=M1.focalDistances() >>> print(‘focal distances:’ , f1) focal distances: FocalLengths(f1=5.0, f2=5.0)